JP2024529935A - Mixed Energy Ion Implantation - Google Patents

Abstract

The ion implantation system and method performs implants with varying energy of the ion beam on the workpiece in a serial single workpiece end station. An acceleration/deceleration stage electrode, a bending electrode, and/or an energy filter control the final energy or path of the ion beam towards the workpiece. The bending electrode or energy filter may form part of the acceleration/deceleration stage or may be located downstream. A scanning device scans the ion beam and/or the workpiece. A power supply provides various electrical bias signals to the electrodes. As the ion beam and/or workpiece is scanned through the ion beam, a controller selectively varies the electrical bias signals based on the desired ion beam energy at the workpiece. A waveform generator may effect the variations and synchronize the electrical bias signals provided to the acceleration/deceleration stage, the bending electrode, and/or the energy filter.

Description

Detailed Description of the Invention

REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of (i) U.S. Provisional Application No. 63/229,751, entitled "BLENDED ENERGY ION IMPLANTATION," filed on August 5, 2021, and (ii) U.S. Provisional Application No. 63/229,663, entitled "CHAINED MULTIPLE ENERGY IMPLANT PROCESS STEPS," filed on August 5, 2021, the contents of all of which are incorporated herein by reference in their entireties.

[Field]
The present invention relates generally to ion implantation systems and, more particularly, to a system and method for providing continuously controlled variable energy to an ion beam delivered to a workpiece during ion implantation.

[background]
Ion implantation is used in the manufacture of semiconductor devices to dope semiconductors with impurities. Ion implantation systems are often utilized to dope workpieces such as semiconductor wafers with ions derived from an ion beam to produce n-type or p-type material doping or to form passivation layers during the manufacture of integrated circuits. Such beam processes are often used to selectively implant wafers with impurities of a particular dopant material at predefined energy levels and in controlled concentrations to produce semiconductor materials during the manufacture of integrated circuits. When used to dope semiconductor wafers, ion implantation systems implant selected ion species into the workpiece to produce the desired extrinsic material. For example, implanting ions derived from a source material such as antimony, arsenic, or phosphorus produces an "n-type" extrinsic material wafer. On the other hand, "p-type" extrinsic material wafers are often derived from ions produced using a source material such as boron, gallium, or indium.

A typical ion implanter includes an ion source, an ion extraction device, a mass analysis device, a beam transport device, and a wafer processing device. The ion source produces ions of the desired atomic or molecular dopant species. These ions are extracted from the source by an extraction system (typically a set of electrodes), which energizes the stream of ions from the source to form an ion beam. The desired ions are separated from the ion beam inside a mass analysis device (typically a magnetic dipole that performs mass dispersion or separation of the extracted ion beam). A beam transport device (typically a vacuum system including a series of focusing devices) transports the ion beam towards the wafer processing device while maintaining or improving the desired properties of the ion beam. Finally, the semiconductor wafers are transferred in and out of the wafer processing device by a wafer handling system, which may include one or more robotic arms to position the wafer to be processed in front of the ion beam and to remove the processed wafer from the ion implanter.

Current ion implantation techniques establish recipes for implanting ions in a particular state into a workpiece (also referred to as a substrate or wafer). The recipe results in a given concentration and depth profile of the ions implanted into the substrate. The concentration and depth profile are largely determined by the type of dopant or desired species to be implanted, the density and composition of the workpiece, and the implantation conditions, such as the energy of the implanted species (which determine the depth to which the ions are implanted), the implantation angle (e.g., tilt or twist) of the workpiece surface relative to the ion beam, and the total implant dose. Additionally, variables such as the temperature of the workpiece and/or the charge state(s) of the implanted ions may be controlled in the implantation recipe to produce the desired implantation results.

In general, it is typical to perform multiple implants of the same species on the same substrate using different combinations of energy, dose, tilt, or twist to establish a desired dopant profile. The dose, tilt, and twist can be adjusted in a single implant by splitting the single implant into multiple implant steps, each with different input parameters. On the other hand, typically, to maintain the integrity of the desired characteristics of the ion beam (e.g., to perform beam tuning), changing the energy of the implant and thus the depth of the implanted ions may require significant adjustments and/or modifications to various settings and/or electrical bias signals supplied to the power supplies and/or components of the ion implantation system. Such adjustments and/or modifications typically increase the time used to set up the ion implantation system (so-called tuning time), thus affecting the productivity of the ion implantation system. Additionally, these beam adjustment steps may require removing and repositioning the workpiece on the workpiece support (e.g., platen or clamp) used to position the wafer in front of the ion beam, resulting in workpiece handling that can further impact the productivity and yield of the system.

[overview]
The present disclosure provides systems and methods for implanting distributions of energy, e.g., at the same or varying doses and/or angles, in a single, continuous implantation process. Thus, the following presents a simplified summary of the disclosure in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the invention. It is not intended to identify key elements of the invention or to delineate the scope of the invention. Its purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented later.

According to an exemplary aspect of the present disclosure, an ion implantation system is provided. An ion source is configured to ionize a dopant material to generate an ion beam. For example, a beamline assembly is disposed downstream of the ion source. The beamline assembly is configured to transport the ion beam toward a workpiece. For example, a scanning apparatus is configured to scan one or more of the ion beam and the workpiece relative to one another along a first scan axis. And, an acceleration/deceleration stage is provided. The acceleration/deceleration stage is configured to receive the ion beam during transport. An end station is disposed downstream of the acceleration/deceleration stage. The end station includes a workpiece support. The workpiece support is configured to selectively position the workpiece in a path of the ion beam.

For example, one or more power sources are operably connected to the acceleration/deceleration stage. The one or more power sources are configured to provide one or more electrical bias signals to the acceleration/deceleration stage. For example, the acceleration/deceleration stage is configured to determine a plurality of energies of the ion beam based on the one or more electrical bias signals.

For example, the controller may be configured to selectively modulate one or more electrical bias signals provided to the acceleration/deceleration stage in conjunction with scanning one or more of the ion beam and the workpiece along the first scan axis. As an example, the selective variation of the one or more electrical bias signals is based at least in part on a position of the ion beam relative to the workpiece and a predetermined implantation profile for the workpiece.

According to another embodiment, a method for ion implantation is provided in which an ion beam is directed toward a workpiece. At least one of the ion beam and the workpiece are scanned relative to one another to implant ions into the workpiece. Energy of the ion beam is selectively varied in conjunction with the scanning of at least one of the ion beam and the workpiece based at least in part on a position of the ion beam relative to the workpiece and a predetermined implantation profile for the workpiece. This causes a resulting depth of ion implantation into the workpiece to be varied in conjunction with the scanning.

According to another exemplary aspect, an ion implantation system is provided having an ion source configured to generate an ion beam and an acceleration/deceleration stage. For example, the acceleration/deceleration stage is configured to receive the ion beam and generate a final ion beam having a final energy associated with the ion beam. For example, the workpiece support is configured to selectively position a workpiece along a path of the final ion beam. The scanning device is configured to scan one or more of the ion beam and the workpiece support relative to one another along a first scan axis and a second scan axis.

For example, one or more power sources are operably connected to the acceleration/deceleration stage. The power sources are configured to provide one or more electrical bias signals to the acceleration/deceleration stage. For example, the one or more electrical bias signals may include one or more of a voltage and a current. Further, for example, a waveform generator is operably connected to one or more of the power sources. The waveform generator is configured to controllably apply a waveform to the one or more electrical bias signals.

Further, for example, the controller is operatively connected to one or more power sources and a waveform generator. The controller is configured to selectively vary one or more electrical bias signals provided to the acceleration/deceleration stage in conjunction with scanning one or more of the ion beam and the workpiece support. In this manner, multiple energies of the ion beam are implanted into the workpiece in a predetermined manner. For example, the selective variation of the one or more electrical bias signals provided to the acceleration/deceleration stage is based at least in part on the waveform, the position of the ion beam relative to the workpiece, and the predetermined energy of the ions implanted into the workpiece.

According to yet another exemplary aspect, an ion implantation system is provided having an ion source configured to form an ion beam and direct the ion beam toward a workpiece. For example, one or more beamline components are configured to transport the ion beam along a beam path. A scanner apparatus is configured to selectively and repeatedly scan one or more of the ion beam and the workpiece along a first scan axis. An acceleration/deceleration stage is disposed downstream of the scanner apparatus. A power supply is configured to provide an electrical bias signal to the acceleration/deceleration stage. For example, the controller is configured to vary or modulate the electrical bias signal provided by the power supply to the acceleration/deceleration stage when one or more of the ion beam and the workpiece are being repeatedly scanned along the first scan axis. This allows for selectively varying the final energy of ions implanted into the workpiece along the first scan axis.

In another example, an ion implantation system is provided that includes a power supply configured to provide an electrical bias signal corresponding to a predetermined waveform. For example, an energy variation component is configured to receive the electrical bias signal and selectively vary the ion beam to a final energy based on the predetermined waveform, where the final energy is selectively variable.

According to yet another exemplary aspect, a process is provided for implanting ions into a single workpiece using a single tuning recipe in multiple sequential implantation steps at different predetermined energies. The process includes setting ion implantation parameters to implant an ion beam at a first predetermined energy and determining a first minimum ion beam angle associated with the first predetermined energy. An ion beam orientation angle is established for the single workpiece based on the determination of the first minimum ion beam angle associated with the first predetermined energy. For example, the ion implantation parameters are adjusted to implant an ion beam at a second predetermined energy. And a minimum ion beam angle associated with the second predetermined energy is determined. For example, the ion beam orientation angle is further controlled for the workpiece based on the determination of the minimum ion beam angle associated with the second predetermined energy. Further, the workpiece is processed to implant ions at the first and second predetermined energies in multiple sequential implantation steps while adjusting the ion beam orientation for the workpiece in each sequential implantation step.

In another exemplary aspect, a method is provided for implanting ions into a single workpiece using a single tailored recipe in multiple sequential implantation steps at different pre-determined energies. In the method, one or more ion implantation parameters are set to implant an ion beam at a first pre-determined energy. One or more ion implantation parameters are further set to implant an ion beam at a second pre-determined energy. Ions are sequentially implanted into the workpiece at the first pre-determined energy and the second pre-determined energy.

In yet another exemplary aspect, a method is provided for implanting ions into a single workpiece using a single tailored recipe in multiple sequential implantation steps at different predefined energies. For example, one or more ion implantation parameters are set to implant an ion beam at a first predefined energy. A minimum ion beam angle associated with the first predefined energy is then determined. Based on the determination of the minimum ion beam angle associated with the first predefined energy, a first ion beam orientation angle is defined for the workpiece. The one or more ion implantation parameters are controlled to implant an ion beam at a second predefined energy. For example, a minimum ion beam angle associated with the second predefined energy is further determined. Based on the determination of the minimum ion beam angle associated with the second predefined energy, a second ion beam orientation angle is defined for the workpiece. Further, ions are sequentially implanted into the workpiece at the first predefined energy and the second predefined energy while controlling each of the first and second ion beam orientations for the ion beam.

To the accomplishment of the foregoing and related ends, the present disclosure comprises the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth illustrative embodiments of the invention in detail. These embodiments are, however, indicative of but some of the various ways in which the principles of the invention are employed. Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of a portion of an ion implanter according to various aspects of the present disclosure.

FIG. 2A is a graph showing uniform distribution of ion dose by energy according to an exemplary embodiment of the present disclosure.

FIG. 2B is a graph showing the derivative of voltage regulation according to an exemplary embodiment of the present disclosure.

FIG. 2C is a graph showing another voltage adjustment according to an exemplary embodiment of the present disclosure.

Figure 3 is a schematic block diagram of an exemplary ion implantation system according to aspects of the present disclosure.

Figure 4 shows a portion of an ion beam in an ion implantation system according to various aspects of the present disclosure.

Figure 5 illustrates a method for optimizing implantation of ions into a workpiece according to various aspects of the present disclosure.

Detailed Description
To the accomplishment of the foregoing and related ends, the present disclosure comprises the structure hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth illustrative embodiments of the invention in detail. These embodiments are, however, indicative of but a few of the various ways in which the principles of the invention are utilized. Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the drawings.

The present invention will now be described with reference to the drawings. Like reference numerals may be used to refer to like elements throughout. It should be understood that the description of these aspects is merely illustrative and should not be taken in a limiting sense. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art that the present invention may be practiced without each and every one of these specific details.

The present disclosure provides systems and methods for implanting a distribution of energies (e.g., at the same or varying doses and/or angles) in a single continuous implantation process without significant previously recognized adjustments and/or workpiece handling. For example, the present disclosure provides a variety of processes ranging from simple to more complex. Simple processes are as simple as implanting two independent implant energies in a single implant. More complex processes have a continuous distribution or range of energies over a range, with fixed or controlled gradients in dose and/or beam angle in the energy distribution or range. For example, the present disclosure may be utilized when it is necessary to produce a so-called box-shaped profile of dopant concentration versus depth. This may be beneficial in semiconductor device manufacturing.

Additionally, the present disclosure provides for pre-tuning of an ion implantation system to multiple recipes prior to implantation. For example, various components of an ion implantation system may be advantageously pre-tuned to all of the multiple recipes for a given workpiece prior to the start of implantation, such that each of the multiple recipes may be selectively employed (i) for implantation into each workpiece during a single implantation, or (ii) in a series of implantation steps that may be processed or performed without removing the workpiece from the workpiece support.

The present disclosure provides for the implantation of a continuous energy distribution, or so-called "blended energy," whereby the energy of ions implanted in a workpiece is dynamically varied and controlled within each path of the ion beam across the surface of the workpiece. The control utilizes a time-varying electrical bias signal, e.g., voltage and/or current, that is applied to or otherwise provided to one or more power supplies associated with the acceleration/deceleration stages (also referred to as acceleration/deceleration electrodes). In addition, scanner waveforms utilized to scan the ion beam and/or control one or more post-final energy elements may be further based at least in part on the time-varying electrical bias signal applied to one or more power supplies associated with the acceleration/deceleration stages, for example. Such elements may include an angular energy filter, or "AEF," and typically include a bending element or the like.

For example, by applying a time-varying voltage to one or more power supplies associated with the acceleration or deceleration stages, a continuously controlled variable energy ion beam can be delivered to a workpiece for ion implantation. Additionally, once the ion beam reaches its final energy, one or more beam bending elements that bend the ion beam can be "servo-off" with respect to the time-varying voltages applied to one or more power supplies associated with the acceleration/deceleration stages. This allows a fixed angle at which the variable energy ion beam impacts the workpiece to be maintained. Alternatively, the angle at which the variable energy ion beam impacts the workpiece can be continuously changed.

As an example, a time-varying voltage may be achieved by incorporating a waveform generator operably connected to one or more power sources and applying one or more waveforms to the power sources. For example, the controller may be configured to modify, vary, maintain, or provide a time-varying voltage to each acceleration/deceleration stage and/or final post-energy element.

As an example, the present disclosure provides for rapid switching of waveforms, energies, and calibration factors as a function of workpiece position (e.g., slow scan or vertical position of the workpiece relative to the ion beam) for a variety of hardware designs. Thus, the present disclosure provides a sufficiently fast response time to be compatible with a variety of other dose and energy patterning functions that may be used in an ion implantation cycle.

As discussed above, the energy control and adjustment capabilities provided by the present disclosure advantageously minimize handling of the workpiece being processed. For example, in contrast to conventional systems in which a workpiece is transferred multiple times between a load lock chamber and a process chamber to achieve multiple energy implants, the present disclosure maintains the workpiece within the process chamber and on the workpiece support while implanting all desired energies into the workpiece without removing the workpiece from its position. Thus, yield loss due to handling errors or queue time effects is lowered and workpiece throughput in the ion implantation process is significantly increased.

Ideally, the present disclosure is suitable for beamline implanters with downstream acceleration/deceleration capabilities (e.g., hybrid scanning implanters with spot beams and single wafer implanters with scanning spot beams or ribbon beams). To maintain energy purity, the implanter may also have an optional angular energy filter (e.g., to remove off-energy particles) to selectively implant substrates with the beam at a specified desired final energy. For example, implantation systems incorporating upstream acceleration components or post-acceleration magnets used for beam parallelism are not excluded by this disclosure. However, such ion implantation systems may be subject to limitations (i) due to the effects on downstream components, or (ii) due to the speed of adjustments required in voltage-based post-acceleration, downstream acceleration, and magnet currents compatible with the performance of AEF-based tools. Thus, the present disclosure does not exclude alternative beamlines that may use magnetic or electrostatic beamline components after acceleration to achieve capabilities similar to other embodiments described herein. However, it will be appreciated that the present invention provides greatest benefits in systems with downstream acceleration or deceleration components and/or in combination with downstream angular bending components. In this case, fast energy changes can be achieved without changing or modifying the electrical biases of upstream components such as the ion source, extraction electrode, mass analyzer, scanner corrector, or parallelizer.

Plasma Immersion Ion Implantation (PIII) or plasma doping tools can also be used to generate voltage ramps to generate doping profiles similar to those provided by the present invention. However, it should be noted that the invention described herein provides a path to dynamically adjustable implant energies for mass-selected species over a much wider energy range than is practically possible with plasma doping.

The present disclosure allows for the creation of a generally mixed box-like dopant energy distribution by providing a number of energies (e.g., any number of energies). Such a distribution is not achievable with only a few ion implant passes at different energies. To achieve such a distribution, for example, deceleration, acceleration, and any angular deflection are controlled by synchronized time-varying voltages or currents at frequencies higher (e.g., an order of magnitude or more higher) than any fast or slow scan of the workpiece or ion beam.

For example, adjusting the shape of the electrical bias signal or waveform applied to the acceleration/deceleration electrodes may be used to adjust the dose weighting of the energy distribution for dopant and/or energy profile adjustment. Energies may be blended at a much higher frequency than the horizontal scan of the ion beam. This allows for a single horizontal angle adjustment, a single uniformity correction waveform, a single vertical angle offset value, and a single set of dose criteria used for energy blending (e.g., each horizontal and vertical beam angle or flux measurement may include the entire distribution of energies). Eliminating the need to adjust each energy in a discrete manner may reduce the total setup time for the ion implantation system while still producing a unique blended dopant profile.

One advantageous aspect of the present disclosure allows for the production of smoother dopant distribution profiles (e.g., when a "box-like" profile is desired) than could reasonably be produced by a series of discrete ion implantation process steps at multiple subsets of energies.

Thus, in accordance with the present invention, a wave generator provides an ion beam with continuously varying energy by implementing high frequency variations in the voltage bias applied to the acceleration/deceleration column. The present disclosure may be advantageously implemented using a scanning pencil beam or so-called scanning spot beam architecture, since the energy can be varied downstream of the scanner using a single component that defines the final energy of the ion beam. This offers many advantages over tuning and other variability that may be undesirably introduced when using upstream components to vary the energy.

The present disclosure provides productivity advantages over conventional systems by eliminating workpiece exchange or exchange time and setup time by implanting multiple energies without the need to realign the beam or move the workpiece to and from the workpiece holder and/or end station. In one particular embodiment, the present disclosure contemplates providing a high frequency variable power supply for the acceleration/deceleration voltage and optional bending voltage. This provides control to synchronize the acceleration/deceleration voltage and bending voltage to maintain a constant angle of the ion beam at the workpiece. As a result, a continuously controlled variable energy distribution is delivered to the workpiece. Thus, all energies can be implanted in the workpiece in a single operation. This is in contrast to implanting the workpiece at a first dose and/or a first angle at a first energy, modifying the system to implant at a second energy, and then implanting the workpiece at a second dose and/or a second angle at the second energy.

The present disclosure provides systems and methods for continuously varying, modulating, oscillating, or slewing in a predetermined energy range for a desired implant as one or more of an ion beam and a workpiece are scanned. For example, a waveform is applied to produce a predetermined energy profile. This defines a custom dopant distribution within the workpiece that cannot be achieved with conventional ion implantation. As an example, a large number of ion implantation energies (e.g., hundreds) may be desired for productivity reasons. Such a large number of energies may be broken down into a smaller number of discrete energies (e.g., 20-30 energies). This would attempt to approximate the desired resulting implant profile in the predetermined energy range.

However, in conventional implants, even when the beamline is adjusted for each of a smaller number of discrete energies, the typically required setup and readjustment (e.g., 20-30 times) amounts to a significantly longer time than is acceptable for setup or adjustment in a multi-energy implant. In addition, conventionally, each beam adjustment step may require the workpiece to be removed from the workpiece support (e.g., platen, chuck, or electrostatic clamp (ESC)) and/or from its position in the process chamber, further extending processing setup times and potentially creating particle contamination and/or workpiece handling issues.

In contrast, according to the present disclosure, only one setting of the beamline is performed as the energy is continuously varied or dynamically changed. For example, if an implant energy from 5 KeV to 25 KeV is desired, a conventional implant process may be divided into nine discrete passes of the workpiece through the ion beam, with the energy being changed in discrete steps between each pass (e.g., 5 KeV; 7.5 KeV; 10 KeV; 12.5 KeV; 15 KeV; 17.5 KeV; 20 KeV; 22.5 KeV; 25 KeV). However, more typically, given the significantly longer setup time required between each pass, a desired 5 KeV to 25 KeV implant would only be divided into three implant steps, e.g., 5 KeV, 15 KeV, and 25 KeV. The result may be a relatively non-uniform aggregate dopant profile that is likely to be unacceptable.

However, the present disclosure provides a much more uniform implant energy profile than previously realized by constantly varying the energy in a predetermined manner over a predetermined energy range and in a single pass of the ion beam over the workpiece. Note that the terms "constantly" and "continuously" are intended to mean changes or variations in energy along a single pass of the ion beam over the workpiece and may include various continuous and/or stepped waveforms or increments. Thus, as the ion beam is swept over the workpiece, the energy is changed at a high rate. For example, the change may be a constant oscillation or change at a sufficiently high frequency so that all locations on the workpiece are exposed to all of the varying energy. The resulting aggregate or total energy profile is much more uniform or "box-like."

As an example, the beam may be moved (e.g., electrostatically scanned) along a first axis in a so-called fast scan direction (e.g., horizontal direction) across the workpiece at a horizontal scan rate of about 41 Hz. Thus, for example, the horizontal movement of the beam may be quantized as about 1000 steps across the workpiece. In the slow scan direction (e.g., vertical direction), the workpiece may be moved (e.g., mechanically scanned) along a second axis. Thus, the vertical scan rate is significantly slower than the horizontal scan rate. In this example, the desired variable energy frequency is significantly higher than the fast scan frequency, which may be on the order of KHz or MHz (e.g., based on the power supply selection). It is contemplated in the present disclosure that it is generally desirable to perform a complete sweep of the energy range before the ion beam advances in the next traverse direction across the workpiece. As a result, all of the desired energy is implanted at each x- and y-position of the workpiece. For example, if the continuous motion of the workpiece relative to the ion beam can be considered to be resolved into individual quantized bits, then each position across the workpiece can be considered a picture element (pixel).

In this manner, the present disclosure provides for all of the desired range of energies to be implanted across the entire workpiece being scanned. This allows any number of different energies to be uniformly doped across the workpiece. For example, each electrical bias signal may control an acceleration/deceleration device (e.g., also referred to as an accel/decel device) and may also control a beam bending device (e.g., also referred to as a bend device). For example, if each voltage can be considered to be a pure triangular waveform, a uniform dose can be provided at each energy step along the waveform. The waveform may be further adjusted to vary the relative dose at different energy intervals along such a continuum. Thus, for example, the waveform induced for the energies may vary the spread or relative concentration of the energies in a given scan.

To provide a general overview of various concepts of the present disclosure, FIG. 1 illustrates an example of a system 100 for implanting ions with continuously controlled variable energy. According to one example, the system 100 includes an ion source 102 configured to ionize a dopant material to generate an ion beam 104. A beamline assembly 106 is disposed downstream of the ion source 102. The beamline assembly is configured to transport the ion beam 104 toward a workpiece 108 disposed on a workpiece support 110 (e.g., a chuck) in an end station 112.

Illustratively, an acceleration/deceleration stage 114 is further provided. The acceleration/deceleration stage is configured to receive the ion beam 104 during transport and produce a continuously controlled variable energy ion beam 116 for implantation into a workpiece 108 selectively disposed within the end station 112. Illustratively, one or more variable power sources 118, 120 (e.g., one or more power sources) are operably connected to the acceleration/deceleration stage 114. The variable power sources provide one or more electrical bias signals 122, 124 (e.g., voltages or currents) to the acceleration/deceleration stage, respectively.

For example, as the ion beam 104 passes through the acceleration/deceleration stage 114, one or more electrical bias signals 122, 124 are applied to one or more electrodes 128 disposed above and below the ion beam. For example, the acceleration/deceleration stage 114 may include one or more acceleration/deceleration electrodes 128 and one or more bending electrodes 126, 130. In this case, the electrical bias signal 122 applied to the acceleration/deceleration electrodes produces a continuously controlled variable energy ion beam 116. And, the electrical bias signal 124 applied to the bending electrodes produces a continuous angular control of the ion beam 104. For example, the one or more electrical bias signals 122, 124 are further selectively varied via one or more waveform generators 132, 134 operably connected to one or more power sources 118, 120 to provide one or more waveforms 136, 138 (e.g., one or more time-varying signals). A controller 140 (e.g., a control system including one or more controllers) is further provided for selectively controlling one or more electrical bias signals 122, 124 through control of one or more power supplies 118, 120 and one or more waveform generators 132, 134. As described further below, the controller 140 is further operable to control (i) other aspects of the system 100, such as the workpiece support 110, and (ii) other components of the beamline assembly 106, such as a beam scanning mechanism, focusing and steering elements, or other beam control structural components.

As an example, the control and feedback signals 142 between the controller 140, one or more power supplies 118, 120, and one or more waveform generators 132, 134 selectively control and vary the energy of the ion beam 104 to define a continuously controlled variable energy ion beam 116. For example, control of the electrical bias signal 122 (e.g., deceleration voltage) provided to the acceleration/deceleration electrodes 128 can selectively vary (increase and decrease) the energy of the ion beam 104 based on the waveform 136 provided from the waveform generator 132 to the power supply 118. Thus, a voltage difference associated with the acceleration/deceleration electrodes is defined. Similarly, control of the electrical bias signal 124 provided to the bending electrode 130 can selectively bend the ion beam 104 upwards or downwards based on the waveform 138 provided from the waveform generator 134 to the power supply 120.

For example, the polarity of one or more of the electrical bias signals 122, 124 may be switched when controlling the acceleration/deceleration and bending of the ion beam 104. For example, different energies of the continuously controlled variable energy ion beam 116 can be obtained when stepping with different voltages applied to the bending electrode 130 and the acceleration/deceleration electrode 128. For example, as described in more detail below, each of the waveforms 136, 138 can be synchronized to a step size of the mechanical scanning of the workpiece 108 (e.g., along the so-called slow scan direction or x-axis). Similarly, when the energy of the continuously controlled variable energy ion beam 116 is changed, the electrical bias signal 124 (e.g., bending voltage) applied to the bending electrode 130 can be changed so that the angular relationship between the continuously controlled variable energy ion beam and the workpiece 108 remains constant. Furthermore, the angular relationship between the continuously controlled variable energy ion beam 116 and the workpiece 108 may be changed when the energy of the continuously controlled variable energy ion beam 116 is changed via control of the electrical bias signal 124.

In another example, when the ion beam 104 is electrostatically or magnetically scanned back and forth (e.g., along a so-called fast scan direction or y-axis), one or more periods of variation (e.g., one or more periods of voltage variation based on one or more waveforms 136, 138) of the electrical bias signals 122, 124 at the acceleration/deceleration electrodes 128 and/or flexion electrodes 130 may be completed prior to or upon reversal of the direction of the ion beam scan. For example, the continuously controlled variable energy ion beam 116 may define an "energy scan" that is varied, cycled, or modulated through synchronization of the electrical bias signals 122, 124 at the acceleration/deceleration electrodes 128 and/or flexion electrodes 130. For example, the energy scan may be varied at a substantially higher frequency than the scanning of the ion beam 104 in the fast scan direction.

Thus, the electrical bias signals 122, 124 supplied or provided to the acceleration/deceleration electrodes 126 and the bending electrodes 130 may be synchronized or otherwise controlled to provide a uniform distribution of energy achieved during implantation into the workpiece 108. For example, the triangular waveform 145 shown in FIG. 2A can be viewed as a single period of substantially small "steps" in the energy variation or modulation. Because the same amount of time is provided in each step, a uniform energy profile substantially similar to the triangular waveform may be achieved. In the example shown in FIG. 2A, approximately 100 scans of a predetermined range of energies may be completed within each scan of the ion beam in a "fast scan" or "step" of the ion beam across the surface of the workpiece or wafer.

When the time spent at each voltage is added together, each voltage is present in the waveform for its respective time. Thus, when multiple energies (e.g., 5 KeV, 5.1 KeV, 5.2 KeV...24.9 KeV, 25 KeV) are implanted in accordance with the present disclosure, each of the multiple energies is implanted for the same time from the lowest energy (e.g., 5 KeV) to the highest energy (e.g., 25 KeV). If a purely triangular waveform is not utilized, for example, the derivative of the waveform can be considered to be equal to the dwell time at a given voltage. For example, the waveform 150 shown in FIG. 2B shows that more time is spent at higher energies and less time is spent at the lower energies before moving to the next energy upon reaching the maximum deceleration voltage (e.g., lowest energy). Thus, for example, an implantation profile in a workpiece can be designed to have a larger dose in the higher energy ranges compared to the lower energies.

The present disclosure provides the ability to implant an arbitrary number of different process steps at different energies at different doses, for example, nearly simultaneously or simultaneously with one pass of the ion beam across the workpiece. In a production environment, for example, the number of implants in a conventional process may be limited (e.g., due to production reasons such as time or cost constraints) by implanting three energies at three different doses in the same mask and then relying on a subsequent annealing step to achieve a particular dopant profile for the workpiece. However, the present disclosure understands that a smoother profile of dopant concentration in the workpiece is desirable for the benefit of the device formed on the workpiece. However, each time energy is added to a conventional process flow, costs are added, such as lost productivity. The present disclosure can provide any number of combinations of energy and dose without substantially any additional cost per process step. Thus, the present disclosure avoids this additional cost.

The present disclosure, for example, advantageously allows for control of dopant concentration, angular distribution, and/or ion implantation depth within a workpiece (e.g., corresponding to the energy of the implant) to correspond to desired device characteristics resulting from the implanted ions. For example, research and design (R&D) may formulate specifications using various models to produce a desired R&D implant profile that requires a particular dopant concentration at a given implant depth. In this case, the specification calls for multiple implants (e.g., 9 or 10 implants) into the workpiece. However, in a production environment, due to various production concerns (e.g., time, wafer handling, and costs associated with each implant), it may be acceptable for only a limited number of implants (e.g., only 2 or 3 implants) to be performed on the workpiece. Thus, instead of performing multiple implants to achieve the desired R&D implant profile in the workpiece, various compromises are typically made to achieve an implant profile that attempts to approximate the desired R&D implant profile within the limited number of implants allowed. However, the present disclosure advantageously results in desired R&D implant profiles and dopant concentrations without the need to make such approximations and compromises.

2C shows another exemplary waveform 160 according to the present disclosure. In the example of FIG. 2C, the waveform includes multiple steps of varying duration. In this case, multiple energies are injected in a single cycle. The multiple energies may be limited (e.g., to three energies). As a result, the waveform may be depicted as having multiple generally flat portions interrupted by multiple steps of voltage. In a simple example, three discrete energies may be achieved by a first long flat portion, a short step, followed by another long flat portion, a short step, followed by yet another long flat portion. In this example, all three energies may be injected in a single injection cycle. For example, the total dose may be set to 1.5e14, since all of the doses injected at the three energies are added together. Thus, all three energies may be injected into the workpiece without removing the workpiece from the workpiece support and the process chamber or end station. Thus, the workpiece is not exposed to atmospheric exposure between steps. And the workpiece is not exposed to workpiece handling hardware or processing steps that could cause the workpiece to misalign and/or potentially fall catastrophically.

Furthermore, since the implant energy levels according to the present disclosure are swept continuously, the profiler (e.g., Faraday cup) may be moved substantially slower than the change in energy described herein, and the average flux of the ion beam may be measured at each position, including all energies. In this manner, the present disclosure may be implemented with only one initial setup time to adjust the ion implantation system for uniformity, angle, etc. Furthermore, the present disclosure may be implemented in a system that includes either acceleration or deceleration to achieve the final energy of the ion beam. For example, the polarity of the power supply that sets the final energy may be switched to produce acceleration or deceleration as desired.

Thus, the present disclosure provides high frequency real-time control of the energy of ions implanted into the workpiece 108 of FIG. 1 by providing a time-varying signal to the voltage applied to the acceleration/deceleration stage 114 (e.g., a mechanism for final acceleration or deceleration of the ion beam 104 before implantation). This can result in a predetermined energy distribution at the workpiece 108. It should be noted that the time-varying signal associated with one or more waveforms 136, 138 can include any desired waveform that can be advantageously controlled to result in any desired energy profile for the workpiece 108.

The one or more waveform generators 132, 134 may be programmed to provide any desired waveform, such as a step, a series of step functions, a curve, or even a randomized form. In this case, the waveform is controlled by a controller. Thus, it is possible to provide a desired dopant concentration and/or energy profile. In this case, the waveform may be designed to provide a desired dopant concentration and/or energy profile at the workpiece 108. In general, the waveform is viewed in an xy axis (x is time and y is the voltage applied to the acceleration/deceleration stage 114), where at any given time, the voltage produces an energy. As a result, the voltage waveform defines a distribution of energy. For example, the derivative of the distribution of energy results in the relative dose per energy level. The percentage of time at a given voltage required to see a given energy is the proportion of the total implant dose that will be achieved at that energy.

2A and 2B show two waveforms 145, 150 synchronized to control both the acceleration or deceleration of the ion beam 104 by the acceleration/deceleration electrode 128 and the bending electrode 130. For example, the bending of the ion beam 104 is synchronized via an electrical bias signal 124 applied to the bending electrode 130 to maintain a constant angle of the ion beam 104 relative to the workpiece 108. Thus, for example, the electrical bias signals 122, 124 for the acceleration/deceleration electrode 128 and the bending electrode 130 may be synchronized by providing a synchronization signal between the respective waveform generators 132, 134, or may be synchronized by a single waveform generator. Although not shown, the present disclosure further contemplates that, for example, a single waveform generator may be implemented. In this case, the polarity of the single waveform generator may be split to provide separate desired electrical biases for the acceleration/deceleration electrode 128 and the bending electrodes 126, 130.

Thus, to achieve a predetermined energy distribution at any given point (position) on the workpiece 108, the controller 140 may control the electrical bias signals 122, 124 to the acceleration/deceleration electrodes 128 and the bending electrodes 126, 130 in a predetermined manner. Alternatively, the invention may be implemented without bending the ion beam 104. In this case, it can be understood that to achieve a predetermined energy distribution at any given point on the workpiece 108, the controller 140 may control the electrical bias signal 122 to the acceleration/deceleration electrodes 128 in a predetermined manner. According to a further example, the energy distribution does not change based on the position on the workpiece 108.

Thus, the present disclosure is generally directed to systems, apparatus, and methods for varying the energy of an ion beam in an ion implantation system. More specifically, the present disclosure is directed to systems, apparatus, and methods for varying the energy of an ion beam as the ion beam is scanned across a workpiece.

The present disclosure is applicable to and contemplates implementation in a variety of implanter architectures. For example, the present disclosure is applicable to at least three types of ion implanters. In one type of ion implanter, a ribbon ion beam is defined and transported along a beamline, where the ribbon beam has a length dimension greater than the width of the workpiece, and the workpiece is scanned substantially across the length dimension in front of the ribbon beam. In a second type of ion implanter, an ion beam having a relatively static cross-sectional dimension (e.g., a pencil beam or spot beam) is used, where the workpiece is moved two-dimensionally relative to the ion beam. In a third type of ion implanter, a hybrid system is used, where a pencil ion beam or spot ion beam is oscillated or scanned relative to the workpiece along a first direction to form a ribbon-shaped scanned beam, and the workpiece is then moved along a second direction intersecting the first direction for global implantation of the workpiece.

The present disclosure's variable control of energy distribution in an ion implantation process, and in particular variable control of implant energy in a continuous manner at the surface of a target workpiece, has not previously been disclosed or contemplated. Accordingly, the present disclosure provides systems, apparatus, and methods for varying the energy distribution of ions implanted by an ion beam in a continuous manner at the workpiece.

It will be appreciated that the above-mentioned application is but one of a variety of processes and applications that may be realized by the continuous and variable energy ion implantation system and method of the present disclosure. The present disclosure and claims are not limited to a solution to this problem, nor to a process for providing a variable energy implant in a workpiece with any shape or specific predetermined contour. The variable, continuous, and non-uniform ion energy implantation process of the present disclosure may be performed in any desired manner to provide a continuously variable implantation depth profile, in addition to a non-continuously variable implantation depth profile. For example, the present disclosure contemplates that a variable ion implantation depth may be utilized in any desired application in which variable ion implantation depth is desired through selective variation of ion implantation energy. There may be many reasons to perform implants at different energies. Implants at different energies translate to different ion implantation depths at the surface of the workpiece. Implants at different energies include, but are not limited to, threshold voltage variation in the workpiece, systematic profile variation of the implant energy profile across the scan width of the workpiece, and the ability to implant multiple dies of different electrical characteristics on a single wafer.

3 illustrates an exemplary ion implantation system 200. In the example of FIG. 3, the ion beam energy may be selectively varied and/or controlled as described herein. The system 200 includes a terminal 202, a beamline assembly 204, and an end station 206. The terminal 202 includes an ion source 208 powered by a high voltage power supply 210. The ion source 208 generates an ion beam 212 and directs the ion beam to the beamline assembly 204. In this regard, the ion source 208 generates charged ions. The charged ions are extracted from the source through an extraction assembly 214 and formed into the ion beam 212. The ion beam is then directed along a beam path in the beamline assembly 204 to the end station 206.

To generate ions, a dopant material (not shown) to be ionized is provided in the generation chamber 216 of the ion source 208. For example, the dopant material may be provided in the chamber 216 from a gas source (not shown). It will be appreciated that in addition to the power source 210, any number of suitable mechanisms (not shown) may be used to excite the free electrons in the ion generation chamber 216. Examples of such mechanisms include RF or microwave excitation sources, electron beam injection sources, electromagnetic sources, and/or cathodes that generate an arc discharge in the chamber. Ions are generated by collisions of the excited electrons with dopant gas molecules. Although positive ions are typically generated, the present disclosure is also applicable to systems that generate negative ions.

Ions are controllably extracted through a slit 218 in the chamber 216 by an ion extraction assembly 214. The ion extraction assembly includes a number of extraction and/or suppression electrodes 220. For example, the ion extraction assembly 214 may include a separate extraction power supply (not shown) for biasing the extraction and/or suppression electrodes 220 to accelerate the ions extracted from the generation chamber 216. The ion beam 212 includes like-charged particles. Thus, within the ion beam, like-charged particles repel each other. It will be appreciated that the ion beam may therefore have a tendency to expand radially outward, i.e., to "blow up" the beam. It will also be appreciated that this blow-up phenomenon may be exacerbated in low energy, high current (e.g., high pervence) beams. In such beams, many similarly charged particles move in the same direction at relatively slow speeds, and although there are many repulsive forces between the particles, there is very little particle momentum to keep the particles moving in the direction of the beam path.

Thus, in general, the extraction assembly 214 is configured so that the ion beam 212 is extracted at a high energy and does not blow up (e.g., so that the particles have sufficient momentum to overcome repulsive forces that would cause the beam to blow up). Furthermore, it is generally advantageous to transport the beam 212 at a relatively high energy throughout the system, where the energy can be reduced as desired just prior to implantation of the ions into the workpiece 222, thereby facilitating beam confinement. It may also be advantageous to generate and transport molecular or cluster ions, whose energy is divided among the dopant atoms of the molecule. Thus, the molecular or cluster ions can be transported at a relatively high energy, but implanted at a lower equivalent energy.

In the exemplary ion implantation system shown in FIG. 3, the beamline assembly 204 includes a beam guide 224, a mass analyzer 226, a scanning system 228, a parallelizer 230, and one or more acceleration or deceleration and/or filtering subsystems 232. The mass analyzer 226 is configured to have an angle of about 90°. The mass analyzer 226 includes one or more magnets (not shown) that serve to generate a (dipole) magnetic field inside the mass analyzer. When the ion beam 212 enters the mass analyzer 226, the ion beam is bent by the magnetic field accordingly so that the desired ions are transported down the beam path, while ions with an inappropriate charge-to-mass ratio are rejected. More specifically, ions with too large or too small charge-to-mass ratios are deflected insufficiently or excessively so that the ions are steered toward the sidewall 234 of the mass analyzer 226. In this manner, the mass analyzer allows ions in the beam 212 having a desired charge-to-mass ratio to pass through the mass analyzer and exit the mass analyzer via the resolving aperture 236.

Also shown is a scanning system 228. For example, the scanning system includes a scanning element 238 and a focusing and/or steering element 240. The scanning system 228 may include a variety of known scanning mechanisms, such as those shown in several U.S. patents, such as 4,980,562 to Berrian et al., 5,091,655 to Dykstra et al., 5,393,984 to Glavish, 7,550,751 to Benveniste et al., and 7,615,763 to Vanderberg et al., the entireties of which are incorporated herein by reference.

In the exemplary scanning system 228, respective power supplies 242, 244 are operatively connected to the scanning element 238 and the focusing and steering element 240 (more specifically, to respective electrodes 238a, 238b and 240a, 240b located therein). The focusing and steering element 240 receives a post-mass analysis ion beam 212 having a relatively narrow profile (e.g., a "pencil" or "spot" beam in the illustrated system 200). The voltage applied to the plates 240a and 240b by the power supply 244 acts to focus and steer the ion beam to an optimal point of the scanning element 238, preferably the scanning apex 246 of the scanning element 238. A voltage waveform applied to scanner plates 238a and 238b by power source 242 (e.g., power source 244 can also serve as power source 242) then scans beam 212 back and forth, expanding beam 212 into an elongated scanning beam or ribbon-shaped beam (e.g., scanning beam 212). Scanning beam 212 has a width or length dimension in the x-axis that can be at least as wide or wider than the target workpiece. It will be appreciated that scan apex 246 can be defined as the point in the optical path where each beamlet or scanned portion of the ribbon beam appears to occur after being scanned by scanning element 238.

It will be appreciated that ion implantation systems of the type described herein may employ different types of scanning systems. For example, the present invention may employ electrostatic or magnetic systems. A typical embodiment of an electrostatic scanning system includes a power supply connected to scanner plates or electrodes 238a and 238b. In this case, the scanner 238 provides a scanning beam. The scanner 238 receives a mass-analyzed ion beam having a relatively narrow profile (e.g., a "pencil" beam in the illustrated system). A voltage waveform applied to the scanner plates 238a and 238b by the power supply 242 then scans the beam back and forth in the X direction (scanning direction) to expand the beam into an elongated ribbon-shaped beam (e.g., a scanning beam). The scanning beam has an effective X-direction width that may be at least as wide or wider than the target workpiece. Similarly, in a magnetic scanning system, a high current source is connected to the coils of an electromagnet. A magnetic field is adjusted to scan the beam. For the purposes of this disclosure, all different types of scanning systems are contemplated. The electrostatic system described herein is used for illustrative purposes only.

The scanning beam 212 then passes through a parallelizer 230. Various parallelizer systems 230 are shown in several U.S. patents, such as 5,091,655 to Dykstra et al., 5,177,366 to Dykstra et al., 6,744,377 to Inoue, 7,112,809 to Rathmell et al., and 7,507,978 to Vanderberg et al., the entirety of which is incorporated herein by reference. As its name implies, the parallelizer 230 deflects an incident scanning pencil beam having diverging rays or beamlets into parallel rays or beamlets 212a. This results in uniform implantation parameters (e.g., implantation angle) at the workpiece 222. In the embodiment shown in this example, the parallelizer 230 includes two dipole magnets 230a, 230b. The dipoles are approximately trapezoidal and oriented as mirror images of each other, allowing the beam 212 to bend in an approximately "s-shaped" manner. In a preferred embodiment, the dipoles have equal angles and opposite bending directions.

The main purpose of the dipole is to transform the multiple diverging rays or beamlets originating from the scanning vertex 246 into multiple nearly parallel rays or beamlets in the form of a relatively thin, elongated, ribbon-shaped beam. As shown herein, the use of two symmetric dipoles results in symmetric properties for the ribbon-shaped beam with respect to beamlet path length and first and higher order focusing properties. Furthermore, similar to the operation of the mass analyzer 226, the s-bend serves to filter and decontaminate the ion beam 212. In particular, the trajectories of neutral particles and/or other contaminants (e.g., environmental particles) entering the ion beam 212 downstream of the mass analyzer 226 are substantially unaffected (or only slightly affected) by the dipole. Thus, these particles continue to travel along the original beam path. As a result, a relatively large amount of these neutral particles that are not bent (or only slightly bent) do not impinge on the workpiece 222 (e.g., the workpiece is positioned to receive the bent ion beam 212). It will be appreciated that it is important to remove such contaminants from the ion beam 212 since such contaminants may have an inappropriate charge and/or energy, etc. Such contaminants are substantially unaffected (or affected to a negligible extent) by the deceleration stage and/or other stages of the system 200. Thus, such contaminants may have a significant (unintended, but generally undesirable) effect on the workpiece 222 in terms of dose, energy, and angle uniformity. This, in turn, may result in unexpected and undesirable resulting device performance.

Downstream of the parallelization component 230 are one or more deceleration stages 232. Examples of deceleration and/or acceleration systems are shown in several U.S. patents, such as Dykstra et al., 5,091,655, Huang, 6,441,382, and Farley et al., 8,124,946, the entire contents of which are incorporated herein by reference. As mentioned above, up to this point in the system 200, the beam 212 is typically transported at a relatively high energy level to mitigate the tendency for beam blow-up. The tendency for beam blow-up may be particularly high when the beam density increases, such as at the resolving aperture 236. As with the ion extraction assembly 214, the scanning element 238, and the focusing and steering element 240, the deceleration stage 232 includes one or more electrodes 232a, 232b operable to decelerate the beam 212.

Two electrodes 220a and 220b, 238a and 238b, 240a and 240b, and 232a and 232b are shown in the exemplary ion extraction assembly 214, scanning element 238, focusing and steering element 240, and deceleration stage 232, respectively. It will be understood that these elements 214, 238, 240, and 232 may have any suitable number of electrodes arranged and biased to accelerate and/or decelerate ions, and to focus, bend, deflect, converge, diverge, scan, collimate, and/or decontaminate the ion beam 212, as shown in U.S. Patent No. 6,777,696 to Rathmell et al., the entirety of which is incorporated herein by reference. Additionally, the focusing and steering element 240 may include electrostatic deflection plates (e.g., one or more pairs of plates), as well as Einzel lenses, quadrupoles, and/or other focusing elements to focus the ion beam. Although not required, it may be advantageous to apply multiple voltages to the deflection plates in the steering and focusing element 240 such that the average of the multiple voltages is zero. The advantage of this is that it avoids the need to introduce additional Einzel lenses to mitigate distortions in the focusing behavior of the element 240. It will be appreciated that "steering" the ion beam 212 is a function of the dimensions of the plates 240a, 240b and the steering voltages applied to them, since, among other things, the beam direction is proportional to the steering voltage and the length of the plates, and inversely proportional to the beam energy.

4 illustrates an exemplary acceleration/deceleration stage 232 in more detail as an electrode column 250 according to one or more aspects of the present disclosure. The electrode column 250 includes a first electrode 254 and a second electrode 254 and a pair of intermediate electrode plates 256 and 258. The first electrode 252 and the second electrode 254 are substantially parallel to each other and define a first opening 260 and a second opening 262, respectively. A gap 264 is defined between the openings 260, 262 and the electrodes 252, 254. The gap 264 is positioned such that an axis 266 substantially perpendicular to the first electrode 252 and the second electrode 254 passes through the gap 264 and passes through the first opening 260 and the second opening 262. The intermediate electrode plates include an upper intermediate gap electrode 256 and a lower intermediate gap electrode 258. A first upper subgap area 268 is defined between the first electrode 252 and the upper mid-gap electrode 256. A first lower subgap area 270 is defined between the first electrode 252 and the lower mid-gap electrode 258. Similarly, a second upper subgap area 272 is defined between the second electrode 254 and the upper mid-gap electrode 256. A second lower subgap area 274 is defined between the second electrode 254 and the lower mid-gap electrode 258. The ion beam 276 passes through the gap 264 and is deflected from the axis 266 by, for example, about 12° and focused at a point 278 downstream of the gap 264. This disclosure further incorporates by reference herein the entire contents of commonly owned U.S. Pat. No. 9,218,941 to Jen et al.

In the illustrated example, specific biases are shown to facilitate explanation of the operation of the electrode array 250 that constitutes the exemplary deceleration/acceleration stage 232. However, for purposes of this disclosure, it will be understood that any suitable electrical bias may be applied to the electrodes to achieve the desired result (e.g., degree of acceleration, deceleration, and/or deflection). Indeed, in the context of this disclosure, where continuously controlled variable ion beam energy is the desired result, it will be understood that variation of the electrical bias signal applied to these electrodes is significant, whether or not it involves variation of the voltage applied to the electrodes or the current passing through the electrodes. However, the bias values of FIG. 4 are useful for illustrating the deceleration of the ion beam 276.

The ion beam 276, more specifically the positive ions contained therein, pass through the first aperture 260 and into the gap 264 at an initial energy level (6 KeV in the illustrated example). To accelerate or decelerate the ions in the beam, the first electrode 252 and the second electrode 254 are biased in different manners. Thus, a potential difference exists between the first electrode 252 and the second electrode 254, and the ions experience a corresponding increase or decrease in energy as they pass through the gap 264 between the first electrode 252 and the second electrode 254. In the example shown in FIG. 4, when a positive ion of the ion beam passes from the first electrode 252, which has a negative 4 KV bias, to the second electrode 254, which has a zero potential (e.g., connected to ground), the positive ion experiences an energy drop of 4 KeV. Thus, the original ion beam energy of positive 6 KeV is reduced to 2 KeV as the ion passes through the gap 264 and experiences an energy drop of 4 KeV. Thus, when the ion beam 276 exits the gap 264 and enters the neutral zone downstream of the gap 264, the ion beam will have a particular resulting energy level (2 KeV in the illustrated example).

It will be appreciated that this is true regardless of the path taken by the ions to pass through the gap 264. In the illustrated example, ions entering the lower sub-gap 270 between the first electrode 252 and the lower mid-gap electrode 258 are accelerated at a rate greater than the rate at which ions entering the side sub-gap 268 between the first electrode 252 and the upper mid-gap electrode 256 are accelerated. This is because the potential difference between the first electrode 252 and the lower mid-gap electrode 258 is greater than the potential difference between the first electrode 252 and the upper mid-gap electrode 256. For example, negative 2.5 KV (negative 4 KV minus negative 6.5 KV) for the lower sub-gap 270 and negative 0.5 KV (negative 4 KV minus negative 4.5 KV) for the upper sub-gap 268.

However, this difference in acceleration is offset by the corresponding difference in potential between the upper and lower mid-gap electrodes 256, 258 and the second electrode 254. In the illustrated example, the second electrode 254 is biased to zero (e.g., connected to ground). Thus, ions coming from the first lower sub-gap 270 are decelerated to a greater extent than ions coming from the first upper sub-gap 268. This offsets the difference in the acceleration of the ions as they enter the gap. This allows all of the ions to have approximately the same energy (e.g., 2 KeV) as they exit the gap. Ions coming from the first lower sub-gap 270 are decelerated to a greater extent because they must traverse a negative 6.5 KV (e.g., the negative 6.5 KV bias of the lower mid-gap electrode 258 minus the 0 V bias of the second electrode 254) while traversing the second lower sub-gap 274. In contrast, ions coming from the first upper subgap 268 are decelerated to a lesser extent because they simply have to traverse a negative 4.5 KV (e.g., the negative 4.5 KV bias of the upper mid-gap electrode 614 minus the 0 V bias of the second electrode 254) while traversing the second upper subgap 272. Thus, due to the effect of the gap, nearly all ions emerge at nearly the same energy level (e.g., 2 KeV) regardless of the different paths they take and the energy levels they pass through.

It will be appreciated that the upper and lower mid-gap electrodes 256, 258 serve two purposes: to attract the ion beam into the gap 264 to (i) accelerate or decelerate the ion beam, and (ii) deflect or bend the beam for beam filtering. For example, the mid-gap plates 256, 258 are generally differentially biased with respect to one another. This can generate an electrostatic field between the mid-gap plates 256, 258 to bend or deflect the beam upwards or downwards, or by various amounts, depending on the magnitude of the electrode bias and the energy of the ion beam. In an exemplary configuration, the upper and lower mid-gap electrodes 256, 258 are biased to negative 4.5 KV and negative 6.5 KV, respectively. Assuming the beam contains positively charged ions, this potential difference will push the positively charged ions passing through the gap 264 downwards toward the more negatively charged lower mid-gap electrode 258. The potential difference ultimately bends or deflects the beam 276 downward (e.g., by about 12°). Bending or deflecting the ions in this manner has the effect of filtering neutral particles from the beam that are not affected by the electric field through which the ion beam passes. Bending or deflecting the ions in this manner also has the effect of filtering ions that may not have substantially the same energy as the ions to be implanted.

It will be appreciated that to maintain this exemplary 12° deflection in light of the varying energy beam, the bias applied to the mid-gap electrodes 256, 258 must also be varied in a corresponding manner. For example, the acceleration of the ion beam can be caused by biasing the electrodes 282, 284 negatively at 4 KV and the electrodes 252, 254 positively at 40 KV, although any bias value(s) may be contemplated. This bias configuration creates a negative potential barrier that extends into the neutral zone. It will be appreciated that the operation of the device with application of these bias voltages is substantially similar to that described, except that the beam 276 is accelerated rather than decelerated. These exemplary values act to increase the energy level of the beam, for example from 80 KeV to 120 KeV, accelerating the beam by a factor of 1.5. Positive ions in the beam 276 are accelerated as they traverse the second upper sub-gap area 272 and the second lower sub-gap area 274.

It will be appreciated that the arrangement, configuration, and/or shape of the upper and lower mid-gap electrodes 256, 258 may be adjusted to facilitate control of the lensing, focusing, deflection, and/or acceleration/deceleration effects on the beam. In the example of FIG. 4, the lower mid-gap electrode 258 has a width that is slightly smaller than that of the upper mid-gap electrode 256 and also has a slightly angled corner 280. These arrangements essentially counteract the stronger lensing effect experienced by ions near the lower mid-gap electrode 258, as the ions experience stronger acceleration and/or deceleration due to the difference in the applied bias. However, for purposes of this disclosure, it will be appreciated that the electrodes 256, 258 may have any suitable configuration, including equivalent shapes. It will be further appreciated that the beam may or may not be bent or may or may not be deflected in the acceleration mode, deceleration mode, and/or drift (e.g., zero acceleration/deceleration) mode. This is because the upper mid-gap electrode 256 and the lower mid-gap electrode 2258, which are primarily responsible for beam bending, operate substantially independently of the first electrode 252 and the second electrode 254, which are primarily responsible for accelerating/decelerating the beam 276. For example, the upper mid-gap electrode and the lower mid-gap electrode may be biased to the same voltage so that acceleration or deceleration can occur without bending the ion beam 276.

The overall net effect of all of the potential differences is focusing, deceleration (or acceleration), and optional deflection of the ions in the beam 276. Deflection of the ion beam results in the removal of the energetic contaminants as neutral particles in the beam. The neutral particles are not impeded by the effect of the electrodes and continue along the original beam path parallel to the axis 266. The contaminants may then encounter, for example, some type of barrier or absorbing structure (not shown). This stops the contaminant's progress and shields any workpiece from the contaminant. In contrast, the trajectory of the deflected ion beam 276 allows the beam to properly encounter and dope selected areas of the workpiece (not shown).

It will be appreciated that the arrangement of the electrodes (e.g., first electrode 252 and second electrode 254, upper mid-gap electrode 256 and lower mid-gap electrode 258) also plays a role in mitigating beam blow-up because this arrangement minimizes the distance the beam 276 must travel before encountering the wafer. Instead of arranging the bending and focusing stages of the beam 276 in series, by simultaneously accelerating, decelerating, or deflecting the beam (e.g., by the upper mid-gap electrode 256 and lower mid-gap electrode 258) and focusing the beam (e.g., by the first electrode 252 and second electrode 254), the end station can be placed closer to the acceleration/deceleration stages of the ion implantation system.

In the illustrated example(s), a particular electrical bias is applied to the electrodes and is shown to facilitate a better understanding of the operation of the deceleration stage 232 of FIG. 3. However, for purposes of this disclosure, it will be understood that any suitable voltage or current may be applied to the electrodes to achieve the desired results, such as the degree of acceleration, deceleration, and/or deflection, as desired. Additionally, for purposes of this disclosure, magnets and currents passing through the magnets may be utilized to achieve these desired results. Furthermore, the particular bias is applied in a selectively and continuously variable and controlled manner to achieve the selective and variable energy control of the present disclosure. However, the bias values shown in FIG. 4 are useful to illustrate the deceleration of the ion beam 276.

It should be noted that the selective change in bias voltage may further be based on one or more predetermined characteristics provided by one of the operators and characterizations of the workpiece 222 of FIG. 3, e.g., repeatable. For example, a "chain implant" may be performed. A discrete number of implants with varying energies are provided to the workpiece 222 in a predetermined sequential order or in a randomized fashion. For example, the predetermined sequential order in the chain implant may be a sequence starting from a low energy and going through a set of predetermined energies in a specific order from the low energy to a high energy. In another example, the predetermined sequential order in the chain implant may be a sequence starting from a high energy and going through a set of predetermined energies in a specific order from the high energy to a low energy. In yet another example, the chain implant may be a sequence starting from any given energy and going through a set of predetermined energies in any specified order or randomized order. Each "chain" may be predetermined, e.g., using a measurement map of the workpiece 222 before implantation. Additionally, each step of the chain may be programmed into the ion implanter control system as multiple sequential steps prior to initiating the implant chain.

The overall effect is thus a continuously controlled uniform or non-uniform variable doping depth profile for the workpiece 222. This allows for defining an energy patterned implant. For example, chains of different energies may be performed repeatedly, with the dose and doping depth profile for the workpiece provided at each step of the chain resulting in a substantially uniform implant profile. Alternatively, topography feedback may be utilized to selectively vary the bias voltage simultaneously with the implant and/or within one or more chain implants.

It should be understood that different types of end stations 206 may be employed in the implantation system 200. For example, a "batch" type end station may simultaneously support multiple workpieces 222 on a rotating support structure. In this case, the workpieces 222 are rotated through the path of the ion beam until all workpieces are fully implanted. On the other hand, a "serial" type end station supports a single workpiece 222 along the beam path for implantation. In this case, the workpieces 222 are implanted one by one in a sequential (serial) manner. Each workpiece 222 is fully implanted before the implantation of the next workpiece 222 begins. In a hybrid system, the workpiece 222 may be mechanically moved in a first direction (Y or slow scan direction) to deliver the beam 212 across the workpiece 222, while the beam may be electrically or magnetically scanned in a second direction (X or fast scan direction). This is disclosed, for example, in commonly assigned U.S. Pat. No. 9,443,698. The entirety of this document is incorporated herein by reference. In contrast, in a so-called two-dimensional mechanical scanning architecture known in the art and exemplified by the Optima HD™ ion implantation system manufactured and sold by Axcelis Technology, Inc., Beverly, Massachusetts, the workpiece 222 may be mechanically moved in front of a fixed-position ion beam in a first (slow) scan direction to deliver the beam 212 across the workpiece 222, while the workpiece is simultaneously scanned in a substantially orthogonal second (fast) scan direction. In addition, in a so-called ribbon beam system, the ion beam may be transported along the beamline such that the ion beam has a length dimension greater than the workpiece. In this case, only the workpiece is scanned in a direction transverse to the length dimension of the beam to implant ions across the entire surface of the workpiece.

The end station 206 in the illustrated example is a "serial" type end station that supports a single workpiece 222 along the beam path for implantation. A dosimetry system 286 is included in the end station 206 near the workpiece position for calibration measurements before the implant operation. During calibration, the beam 212 passes through the dosimetry system 286. The dosimetry system 286 includes one or more profilers 288. The profiler 288 may measure the profile of the scanning beam by continuously traversing a profiler path 290. For example, the profiler 288 may include a current density sensor, such as a Faraday cup, that measures the current density of the scanning beam. In this case, the current density is a function of the implant angle (e.g., the relative orientation between the beam and the mechanical surface of the workpiece and/or the relative orientation between the beam and the crystal lattice structure of the workpiece). The current density sensor moves approximately orthogonally to the scanning beam. Thus, the current density sensor typically traverses the width of the ribbon beam. As an example, the dosimetry system measures both the beam density distribution and the angular distribution. As described in the literature, a moving profiler senses currents behind a mask with slots to measure the beam angles. The displacement of each individual beamlet from the slot position after a short drift can be used to calculate the beamlet angle. It will be appreciated that this displacement can be referred to as a calibrated basis for the beam diagnostics in the system.

The dosimetry system 286 is operably connected to a control system 292. The dosimetry system receives command signals from the control system and provides measurements to the control system. The control system 292, which may include, for example, a computer, a microprocessor, etc., may be operable to obtain measurements from the dosimetry system 286 and calculate the average angular distribution of the scanned ribbon beam at the workpiece. Similarly, the control system 292 is operably connected to the terminal 202 from which the beam of ions is generated, as well as to the mass analyzer 226 of the beamline assembly 204, to the scanning element 238 (e.g., via a power supply 242), to the focusing and steering element 240 (e.g., via a power supply 244), to the parallelizer 230, and to the acceleration/deceleration stage 232. Thus, any of these elements may be adjusted by the control system 292 to facilitate desired ion implantation parameters based on values provided by the dosimetry system 286 or any other ion beam measuring or monitoring device. Typically, the control signals may be generated based on experimental data collected through experimentation using look-up tables stored in a memory module.

As an example, the ion beam may be initially established according to predetermined beam adjustment parameters (e.g., stored/loaded in the control system 292). Then, based on feedback from the dosimetry system 286, the scanner 238 may be adjusted to change the scanning speed of the scanning beam, thereby varying the ion dose at the workpiece. Similarly, the energy level of the beam may be changed and the junction depth adjusted, for example, by adjusting the bias applied to the electrodes in the ion extraction assembly 214 and/or the deceleration stage 232, thereby adjusting the acceleration/deceleration stage 232 and/or the ion extraction assembly. Correspondingly, the strength and orientation of the magnetic field or electric field(s) generated in the scanner may be adjusted, for example, by adjusting the bias voltage applied to the scanning electrodes. The implant angle may be further controlled, for example, by adjusting the voltage applied to the steering element 240 or the acceleration/deceleration stage 232.

In one aspect of the present invention, a control system 292 is provided. The control system 292 is configured to establish a predetermined scanning pattern on the workpiece 222, where the workpiece is exposed to a spot ion beam or a pencil beam by controlling the scanning system 228. For example, the control system 292 is configured to control various characteristics of the ion beam, such as the beam density and current of the ion beam, as well as other characteristics associated with the ion beam (e.g., the energy of the ion beam). In addition, the controller 292 is configured to control the scanning speed of the workpiece 222 disposed on the workpiece support 294. For example, the workpiece support 294 is operably connected to a movement mechanism (e.g., a robotic device or other device) not shown. The movement mechanism is configured to move the workpiece support 222, which is disposed on the workpiece support, through the ion beam 212.

Further, in the context of the present disclosure for providing a continuously controlled variable energy ion beam in the ion implantation system 200, the control system 292 is configured to modify and adjust the electrical bias signal 295 applied to the various subsystems. For example, the control system 292 is configured to control the electrical bias signal 295 provided to the deceleration/acceleration stage 232 by further controlling one or more waveform generators 296 that provide one or more waveforms 298 to one or more variable power supplies 299. In this case, the energy of the ion beam 212 in the ion implantation system is based on one or more waveforms applied to the various electrodes as illustrated herein.

For the exemplary ion implantation system 200 described herein, the control system 292 may be configured to modify and change the scan voltage applied to the scanner 228. And, to adjust the energy and deflection of the ion beam accordingly, the control system 292 may be further configured to modify and change the bias voltage applied to the acceleration/deceleration stage 232 based on a waveform in synchronism with the scan voltage. For example, the changes to the scan voltage and bias voltage may be performed in discrete steps or in a continuous (e.g., non-discrete) manner without removing the workpiece from the platen or processing environment. This may provide various advantages over known systems and methods.

It will also be appreciated that the present disclosure may be combined with configurations known in the art to provide even greater variability in the ion implantation process during ion implantation. Configurations of the present disclosure for providing continuously variable energy control of the implantation process may be combined with other configurations for providing variable dose control of the ion implantation process to achieve variable energy and dose ion implantation at the wafer surface.

Similarly, it may be desirable to provide ions of different charge states to vary the beam current at a given kinetic energy of the beam. The present disclosure for providing continuous variable energy control of an implantation process may be combined with configurations for providing variable charge states of an ion implantation process to achieve variable energy and/or variable dose ion implantation at the surface of a workpiece. Similarly, it may be desirable to provide a workpiece at a temperature below ambient or above ambient to achieve a particular desired result. Thus, the present disclosure for providing continuous variable energy control of an implantation process may be combined with configurations for providing a cold or hot workpiece in an ion implantation process to achieve variable energy ion implantation at a wafer surface.

As shown in FIG. 5, in accordance with the present disclosure, the system described herein implements a method 300 for implanting ions at various depths. Although the exemplary method is illustrated and described herein as a series of acts or events, it should be noted that the present disclosure is not limited by the order of the acts or events shown, and that some steps may be performed in a different order and/or simultaneously with other steps in accordance with the present disclosure than those steps illustrated and described herein. Furthermore, not all steps shown are required to implement a method in accordance with the present disclosure. Furthermore, it will be understood that the method may be performed in conjunction with the systems illustrated and described herein, or in conjunction with other systems not described herein.

The method 300 of FIG. 5 begins with act 302 of providing a workpiece on a workpiece support. In act 304, an ion beam, such as a spot ion beam, is provided. Then, in act 306, the ion beam is mass analyzed. In act 308, one or more of the workpiece and the ion beam may be scanned relative to the other. For example, in act 308, the workpiece is mechanically scanned in two orthogonal directions. In another example, the ion beam is electrostatically or magnetically scanned in a first direction and mechanically scanned in a second direction. In yet another example, the ion beam is electrostatically scanned in two non-parallel directions.

In Act 310, as the ion beam is scanned across the workpiece, the energy of the ion beam is selectively varied in a continuous manner with the predetermined waveform as it is scanned in Act 308. Thus, the resulting depth of implantation of ions into the workpiece varies along the surface of the workpiece.

Thus, the present disclosure is directed to an ion implantation system and method for varying the energy of an ion beam as it moves across a workpiece or vice versa. This can be accomplished by varying the electrical bias applied to the acceleration/deceleration electrodes, which can continuously vary the energy of the ions delivered to the workpiece. As a result, a predetermined variable energy ion implantation depth can be achieved in the workpiece based on a predetermined set of electrical bias signals or waveforms provided to the acceleration/deceleration electrodes. In a preferred embodiment, the present disclosure can provide a continuously controlled variable energy pattern according to a continuous function that is mapped at the workpiece and/or mapped in a matrix. The energy pattern can be used to program the energy of the beam as a function of position at the workpiece. For example, the present disclosure can be implemented by creating a spatial map in a memory, where each cell of the memory location corresponds to a unique energy for an x and y location on the workpiece. It will be appreciated that the present disclosure can be included in a system for providing variable energy implantation as a form of continuously variable energy, or as a form of a step function change in energy, or other form. The variation of the energy profile across the surface of the workpiece may be symmetrical and may be set in quadrants (e.g., _{energy X1} at a particular location Q1, energy _X2 at _Q2 ), or may be set in other manners.

The exemplary ion implantation system architecture described herein for illustrative purposes is particularly suited to achieving a continuous change in ion beam energy at the surface of the workpiece in that the system 200 of FIG. 3 introduces a scanning spot beam, which is electronically or magnetically scanned across the surface of the workpiece. This scanning of the spot beam allows the ion beam energy to be modulated or changed as the beam is scanned. When the beam is scanned to impinge on a selected location on the wafer, the beam passes through all optical elements in the beamline. Thus, the beam can be modified to change its energy to a selected energy prior to impinging on the wafer. Advantageously, the change in beam energy can be achieved to be synchronized with the x and y scanning functions of the scanner and/or end station. In this case, the energy of the scanning beam can be changed as a function of x and y. Advantageously, in the exemplary ion implantation system described herein, the final beam energy can be changed by a bias voltage applied to a single downstream component (i.e., the deceleration/acceleration stage 232). In this case, the ion energy can be changed, but the cumbersome and complicated tuning requirements required to change the electrical bias in an upstream component (e.g., the extraction electrode 214 located immediately downstream of the ion source 208) that would then affect the bias of other downstream components to maintain the desired ion beam integrity and characteristics can be eliminated. In addition, the bias voltages applied to the acceleration/deceleration and deflection energy filter aspects can be varied as a function of the x and y positions of the scanning beam. In this case, the ion beam can be constrained to move on the same path relative to the wafer regardless of changes in its energy.

It will be appreciated that all of the selective biasing of the components and subsystems may be accomplished through the control system 292. It will be appreciated that all of the selective biasing may be accomplished using a feedback loop input to the acceleration/deceleration stage and energy filter based on the position of the beam output from the scanning system. However, it will also be appreciated that a feedback loop is not a requirement for achieving the continuously controlled variable energy ion implantation mechanism of the present disclosure, as a preprogrammed ion beam energy profile may be advantageously employed to achieve the selectively variable energy ion implantation of the present disclosure. In this manner, the ion beam energy may be selectively varied from die to die, or from any other mechanism or region, using a feedback loop in response to the x and y coordinate positions of the beam on the wafer, or using any predetermined desired pattern.

The continuously controlled variable energy ion implantation of the present disclosure may be achieved using a map of the workpiece. In this case, the continuous and controlled variation of the one or more voltages respectively supplied to one or more electrodes in the electrode array and/or energy filter is based on a map of the workpiece disposed on the workpiece support. Alternatively, the ion implantation system of the present disclosure may be provided with one or more detectors (e.g., optical detectors, cameras, etc.) configured to detect one or more of the workpieces disposed on the workpiece support. In this case, the continuous variation of the one or more voltages respectively supplied to one or more of the electrode arrays of the acceleration/deceleration stage and/or energy filter is further based on feedback from the detector. In this alternative embodiment, the detector may preferably be configured to detect one or more of the thickness of the workpiece, the thickness of a layer located on the workpiece, a die pattern on the workpiece, an edge of the workpiece, a center of the workpiece, or a predetermined area on the workpiece. In this case, the detected information is provided as an input for continuously varying the energy of the ion beam.

While the present invention has been illustrated and described with respect to one or more embodiments, it will be understood that changes and/or modifications may be made to the illustrated examples without departing from the spirit and scope of the appended claims. In particular, with respect to the various functions performed by the above-described components or structures (blocks, units, engines, assemblies, devices, circuits, systems, etc.), the terms used to describe such components (including any reference to "means") are intended to correspond to any component or structure that performs the specified function of the described component (i.e., is functionally equivalent) but is not structurally equivalent to the disclosed structure that performs the function in the exemplary embodiment of the invention illustrated herein, unless otherwise specified. In addition, although a particular configuration of the present invention may be disclosed with respect to only one of multiple embodiments, such configuration can be combined with one or more other configurations of other embodiments as may be desired and advantageous for any given or specific application. Additionally, to the extent the terms "including," "includes," "having," "has," "with," or variations of these terms are used in any of the detailed description and claims, these terms are intended to be as inclusive as the term "comprising."

FIG. 1 is a block diagram of a portion of an ion implanter in accordance with various aspects of the present disclosure. 1 is a graph illustrating uniform distribution of ion dose by energy according to an exemplary embodiment of the present disclosure. 1 is a graph illustrating a derivative of voltage regulation according to an exemplary embodiment of the present disclosure. 11 is a graph illustrating another voltage regulation according to an exemplary embodiment of the present disclosure. FIG. 1 is a schematic block diagram of an exemplary ion implantation system in accordance with aspects of the present disclosure. 1 illustrates a portion of an ion beam in an ion implantation system in accordance with various aspects of the present disclosure. 1 illustrates a method for optimizing implantation of ions into a workpiece according to various aspects of the present disclosure.

Claims (63)

1. An ion implantation system comprising:
an ion source for ionizing a dopant material to generate an ion beam;
a beamline assembly disposed downstream of the ion source for transporting the ion beam toward a workpiece;
a scanning device for scanning one or more of the ion beam and the workpiece relative to one another along a first scan axis;
an acceleration/deceleration stage for receiving the ion beam during transport of the ion beam;
an end station disposed downstream of the acceleration/deceleration stage;
one or more power sources operatively connected to the acceleration/deceleration stage to provide one or more electrical bias signals to the acceleration/deceleration stage;
A controller,
the end station includes a workpiece support for selectively positioning the workpiece within a path of the ion beam;
the acceleration/deceleration stage defines a plurality of energies of the ion beam based on one or more of the electrical bias signals;
the controller selectively varies one or more of the electrical bias signals supplied to the acceleration/deceleration stage in conjunction with scanning one or more of the ion beam and the workpiece along the first scan axis;
An ion implantation system, wherein selectively varying one or more of the electrical bias signals is based at least in part on a position of the ion beam relative to the workpiece and a predetermined implantation profile for the workpiece. the selective variation of one or more of the electrical biasing signals is further based at least in part on a waveform applied to one or more of the electrical biasing signals;
The ion implantation system of claim 1 , wherein the predetermined implantation profile is substantially defined by the waveform. The ion implantation system of claim 2, further comprising a waveform generator that generates the waveform. The ion implantation system of claim 3, wherein the waveform generator is operatively connected to one or more of the power sources and selectively applies the waveforms to the power sources to generate one or more of the electrical bias signals. the waveform generator is operatively connected to the controller;
4. The ion implantation system of claim 3, wherein the waveform generator continuously varies the one or more electrical bias signals supplied to the acceleration/deceleration stage along the scanning of one or more of the ion beam and the workpiece along the first scan axis. the scanning device scans one or more of the ion beam and the workpiece back and forth relative to one another along the first scan axis at a first scan frequency;
The ion implantation system of claim 1 , wherein the controller selectively varies one or more of the electrical bias signals at a bias variation frequency that is greater than the first scan frequency. The ion implantation system of claim 6, wherein the bias change frequency is at least one order of magnitude greater than the first scan frequency. The ion implantation system of claim 1, wherein the scanning device scans one or more of the ion beam and the workpiece support relative to one another along a second scanning axis that is non-parallel to the first scanning axis. The ion implantation system of claim 8, wherein the scanning device includes one or more of an electrostatic scanner and a magnetic scanner that electrostatically and magnetically scan the ion beam, respectively, along at least the first scanning axis. The ion implantation system of claim 9, wherein the scanning device further includes a mechanical scanning device that mechanically scans the workpiece support along the second scan axis. The ion implantation system of claim 8, wherein the first scan axis is orthogonal to the second scan axis. The ion implantation system of claim 8, wherein the scanning device includes a mechanical scanning device that mechanically scans the workpiece support along the first scanning axis and the second scanning axis. the one or more power sources include one or more selectively variable power sources;
The ion implantation system of claim 1 , wherein the one or more electrical bias signals include one or more of a voltage and a current. The ion implantation system of claim 1, wherein the selective variation of one or more of the electrical bias signals is further based on one or more predetermined characteristics provided by one of an operator and a characterization of the workpiece. The ion implantation system of claim 1, wherein the predetermined implantation profile includes a predetermined dopant energy distribution across the workpiece. The ion implantation system of claim 1, wherein the selective variation of one or more of the electrical bias signals is further based on feedback from the scanning device corresponding to a position of the ion beam relative to the workpiece. The ion implantation system of claim 1, wherein the selective variation of one or more of the electrical bias signals includes a predetermined sequence of a plurality of electrical bias signals. The ion implantation system of claim 1, wherein the selective variation of one or more of the electrical bias signals is randomized. the acceleration/deceleration stage includes an electrode array having one or more electrode pairs;
The ion implantation system of claim 1 , wherein one or more of the electrical bias signals are provided to one or more of the electrode pairs in the electrode array. 20. The ion implantation system of claim 19, wherein the electrode array includes one or more of an ion beam accelerator, an ion beam decelerator, and a bent electrode. The ion implantation system of claim 1, wherein the selective variation of one or more of the electrical bias signals results in a uniform dose of ions across a predetermined energy range across the workpiece. a detector for detecting one or more workpiece attributes associated with the workpiece disposed on the workpiece support;
The ion implantation system of claim 1 , wherein the selective variation of one or more of the electrical bias signals is further based on feedback from the detector. the detector comprises an optical detector;
23. The ion implantation system of claim 22, wherein the one or more workpiece attributes include one or more of a thickness of the workpiece, a thickness of a layer located on the workpiece, a die pattern on the workpiece, an edge of the workpiece, a center of the workpiece, and a predetermined area on the workpiece. further comprising an energy filter having at least one bent electrode;
At least one of the one or more power sources is further operably connected to at least one of the flexion electrodes and provides at least one of the one or more electrical bias signals to the flexion electrodes;
The ion implantation system of claim 1 , wherein at least one of the bending electrodes deflects the ion beam as a function of one or more of the electrical bias signals supplied to the acceleration/deceleration stage. The ion implantation system of claim 1, wherein the controller controls one or more of the ion source, the beamline assembly, the scanning device, the acceleration/deceleration stage, and the end station based on a plurality of implantation recipes. 26. The ion implantation system of claim 25, wherein the controller selects one of the plurality of implantation recipes based at least in part on a position of the ion beam relative to the workpiece and the predetermined implantation profile for the workpiece. 1. A method for ion implantation comprising the steps of:
directing an ion beam toward a workpiece;
implanting ions into the workpiece by scanning one or more of the ion beam and the workpiece relative to one another;
selectively varying an energy of the ion beam along with scanning one or more of the ion beam and the workpiece based at least in part on a position of the ion beam relative to the workpiece and a predetermined implant profile for the workpiece;
A method wherein the resulting depth of implantation of ions into the workpiece varies with scanning. 28. The method of claim 27, wherein selectively varying the energy of the ion beam includes varying an electrical bias on electrodes disposed along a path of the ion beam based on a waveform. 29. The method of claim 28, wherein the final energy of the ions at the workpiece is determined by varying the electrical bias on the electrodes. 29. The method of claim 28, wherein the electrodes include one or more of an ion beam accelerator electrode, an ion beam decelerator electrode, and a bend electrode. Selectively varying the energy of the ion beam further comprises varying the electrical bias on the bent electrodes;
the bent electrodes angularly deflect the ion beam;
31. The method of claim 30, wherein the change in electrical bias on the bend electrodes is synchronized with the change in electrical bias on the ion beam accelerator electrodes or the ion beam decelerator electrodes. 28. The method of claim 27, further comprising: the predetermined implantation profile being defined over an entire surface of the workpiece. 28. The method of claim 27, further comprising preconditioning one or more components defining the ion beam in accordance with a plurality of recipes for ion implantation into the workpiece prior to scanning the ion beam and one or more of the workpieces relative to one another. 28. The method of claim 27, further comprising preconditioning one or more components defining the ion beam according to a plurality of recipes for implanting ions into the workpiece prior to scanning the ion beam and one or more of the workpieces relative to one another. 1. An ion implantation system comprising:
an ion source that generates an ion beam;
an acceleration/deceleration stage that receives the ion beam and generates a final ion beam having a final energy associated with the ion beam;
a workpiece support for selectively positioning a workpiece along a path of the final ion beam;
a scanning device for scanning one or more of the ion beam and the workpiece support relative to one another along a first scan axis and a second scan axis;
one or more power sources operatively connected to the acceleration/deceleration stage to provide one or more electrical bias signals to the acceleration/deceleration stage;
a waveform generator operatively connected to one or more of the one or more power sources to controllably apply a waveform to one or more of the electrical bias signals;
a controller operatively connected to one or more of the power sources and the waveform generator;
the controller selectively varies one or more of the electrical bias signals supplied to the acceleration/deceleration stage in conjunction with scanning one or more of the ion beam and the workpiece to implant multiple energies of the ion beam into the workpiece in a predetermined manner;
and selectively varying one or more of the electrical bias signals supplied to the acceleration/deceleration stage is based at least in part on the waveform, a position of the ion beam relative to the workpiece, and a predetermined energy of ions implanted into the workpiece. The ion implantation system of claim 35, wherein the controller controls the waveform generator to provide the predetermined energy of ions implanted into the workpiece. the scanning device scans the ion beam along the first scan axis at a first frequency;
the scanning device scans the workpiece along the second scan axis at a second frequency;
36. The ion implantation system of claim 35, wherein the first frequency is at least an order of magnitude greater than the second frequency. the selectively varying one or more of the electrical bias signals provided to the acceleration/deceleration stage selectively varying at a third frequency;
38. The ion implantation system of claim 37, wherein the third frequency is at least an order of magnitude greater than the first frequency. The ion implantation system of claim 35, wherein one or more of the ion source, the deceleration/acceleration stage, the workpiece support, the scanning device, the one or more power supplies, and the waveform generator are pre-tuned for a plurality of implantation recipes. The ion implantation system of claim 39, wherein the controller selects one of the plurality of implantation recipes based at least in part on the waveform, the position of the ion beam relative to the workpiece, and the predetermined energy of ions implanted into the workpiece. 1. An ion implantation system comprising:
an ion source for forming an ion beam and directing the ion beam toward a workpiece;
one or more beamline components that transport the ion beam along a beam path;
a scanner device for selectively and repeatedly scanning one or more of the ion beam and the workpiece along a first scan axis;
an acceleration/deceleration stage located downstream of the scanner device;
a power supply for providing an electrical bias signal to the acceleration/deceleration stage;
and a controller that selectively varies the final energy of ions implanted into the workpiece along the first scan axis by varying the electrical bias signal provided from the power supply to the acceleration/deceleration stage as one or more of the ion beam and the workpiece are repeatedly scanned along the first scan axis. The ion implantation system of claim 41, wherein the controller controls one or more of the ion sources, one or more of the beamline components, the scanner device, and the acceleration/deceleration stage based on a plurality of implantation recipes. The ion implantation system of claim 41, wherein the scanner device selectively traverses one or more of the ion beam and the workpiece along a second scan axis that is generally orthogonal to the first scan axis. The scanner device includes:
repeatedly traversing the ion beam along the first scan axis at a first frequency;
traversing the workpiece along the second scan axis at a second frequency;
44. The ion implantation system of claim 43, wherein the first frequency is at least an order of magnitude greater than the second frequency. the electrical bias signal supplied to the acceleration/deceleration stage is varied at a third frequency;
45. The ion implantation system of claim 44, wherein said third frequency is greater than said first frequency. The ion implantation system of claim 41, wherein the electrical bias signal supplied to the acceleration/deceleration stage is varied in a predetermined manner. The ion implantation system of claim 46, wherein the electrical bias signal supplied to the acceleration/deceleration stage is varied to provide uniform implantation of multiple energies onto the surface of the workpiece. The ion implantation system of claim 46, wherein the electrical bias signal supplied to the acceleration/deceleration stage is varied to provide a plurality of predetermined patterns of energy to the surface of the workpiece. 1. An ion implantation system comprising:
a power supply for providing an electrical bias signal corresponding to a predetermined waveform;
an energy variation component that receives the electrical bias signal and selectively varies the ion beam to a final energy based on a predetermined waveform;
An ion implantation system wherein the final energy is selectively variable. The ion implantation system of claim 49, further comprising a controller for selectively varying the predetermined waveform. an ion beam scanner for scanning the ion beam along a first scan axis;
50. The ion implantation system of claim 49, wherein the electrical bias signal corresponding to a predetermined waveform is supplied to the energy varying component while the ion beam is scanned along the first scan axis. a workpiece scanner for selectively scanning a workpiece relative to the ion beam along a second scan axis;
52. The ion implantation system of claim 51, wherein a frequency of scanning of the ion beam along the first scan axis is greater than a frequency of scanning of the workpiece along the second scan axis. 53. The ion implantation system of claim 52, wherein the frequency of the predetermined waveform is greater than a frequency of scanning of the ion beam along the first scan axis. the energy changing component includes an acceleration/deceleration stage and a bending electrode;
53. The ion implantation system of claim 52, wherein the bending electrode changes a path of the ion beam based on the electrical bias signal corresponding to a predetermined waveform supplied to the acceleration/deceleration stage. The ion implantation system of claim 54, wherein the predetermined waveform is synchronized with one or more of the ion beam scanner and the workpiece scanner. a controller configured with a plurality of tuning recipes for modifying a plurality of properties of the ion beam;
55. The ion implantation system of claim 54, wherein at least the acceleration/deceleration stages correspond to a plurality of the adjustment recipes for ion implantation. The ion implantation system of claim 56, wherein the controller selects one of the plurality of conditioning recipes based at least in part on the predetermined waveform and the position of the ion beam relative to the workpiece. The ion implantation system of claim 57, wherein the controller selects one of the plurality of conditioning recipes based at least in part on the predetermined waveform, the position of the ion beam relative to the workpiece, and a predetermined energy of ions implanted on the workpiece. The ion implantation system of claim 49, wherein the energy changing component includes one or more of an acceleration electrode, a deceleration electrode, and an angular energy filter. a scanning mechanism for scanning the ion beam along a first axis;
50. The ion implantation system of claim 49, wherein said electrical bias signal corresponding to said predetermined waveform is synchronized with said scanning mechanism. 1. A method for implanting ions into a single workpiece using a single tailored recipe in multiple sequential implantation steps at different predetermined energies, comprising:
setting ion implantation parameters to implant the ion beam at a first predetermined energy;
determining a first minimum ion beam angle associated with the first predetermined energy;
determining an ion beam orientation angle for a single said workpiece based on the determination of the first minimum ion beam angle associated with the first predetermined energy;
adjusting the ion implantation parameters to implant the ion beam at a second predetermined energy;
determining a second minimum ion beam angle associated with the second predetermined energy;
controlling the ion beam orientation angle for a single said workpiece based on the determination of the second minimum ion beam angle associated with the second predetermined energy;
and processing a single workpiece to implant ions at the first and second predetermined energies in multiple sequential implantation steps while adjusting the ion beam orientation angle relative to the single workpiece in each sequential implantation step. 1. A method for implanting ions into a single workpiece using a single tailored recipe in multiple sequential implantation steps at different predetermined energies, comprising:
setting one or more ion implantation parameters to implant the ion beam at a first predetermined energy;
setting one or more of the ion implantation parameters to implant the ion beam at a second predetermined energy;
and sequentially implanting an ion beam into a single said workpiece at said first predetermined energy and said second predetermined energy. 1. A method for implanting ions into a single workpiece using a single tailored recipe in multiple sequential implantation steps at different predetermined energies, comprising:
setting one or more ion implantation parameters to implant the ion beam at a first predetermined energy;
determining a minimum ion beam angle associated with the first predetermined energy;
determining a first ion beam orientation angle for a single said workpiece based on the determination of the minimum ion beam angle associated with the first predetermined energy;
controlling one or more of the ion implantation parameters to implant the ion beam at a second predetermined energy;
determining a second minimum ion beam angle associated with a second predetermined energy;
determining a second ion beam orientation angle for the single workpiece based on the determination of the second minimum ion beam angle associated with the second predetermined energy;
and sequentially implanting ion beams into a single said workpiece at said first predetermined energy and said second predetermined energy while controlling both respective first and second ion beam orientations for said ion beam.

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