TWI757242B - Thermal management systems and methods for wafer processing systems - Google Patents

Abstract

A workpiece holder includes a puck having a cylindrical axis, a radius about the cylindrical axis, and a thickness.  At least a top surface of the puck is substantially planar, and the puck defines one or more thermal breaks.  Each thermal break is a radial recess that intersects at least one of the top surface and a bottom surface of the cylindrical puck.  The radial recess has a thermal break depth that extends through at least half of the puck thickness, and a thermal break radius that is at least one-half of the puck radius.  A method of processing a wafer includes processing the wafer with a first process that provides a first center-to-edge process variation, and subsequently, processing the wafer with a second process that provides a second center-to-edge process variation that substantially compensates for the first center-to-edge process variation.

Description

Thermal management systems and methods for wafer processing systems

CROSS REFERENCE TO RELATED APPLICATIONS: This disclosure is the subject of co-owned US Patent Application No. 14/820,422 (Attorney Docket No. A23056/K949499) filed concurrently with this application on August 2015 filed May 6, and the entirety of this US application is incorporated herein by reference for all purposes.

The present disclosure has broad application in the field of processing equipment. More specifically, systems and methods for providing spatially tailored processing of workpieces are disclosed.

Integrated circuits and other semiconductor products are often fabricated on the surface of substrates called "wafers." Sometimes processing is performed on groups of wafers held in the carrier, while at other times processing and testing is performed on one wafer at a time. The wafer can be positioned on the wafer holder while performing a single wafer process or test. Other workpieces can also be processed on similar fixtures. The fixture may be temperature controlled to control the temperature of the workpiece for processing.

In one embodiment, a workpiece holder positions a workpiece for processing. The positioning disk is characterized by a cylindrical shaft, a positioning disk radius around the cylindrical shaft, and a positioning disk thickness. The puck radius is at least four times the puck thickness, at least one top surface of the cylindrical puck is substantially planar, and the cylindrical puck defines one or more radial thermal insulators. Each heat interrupter is characterized as a radial notch that intersects at least one of the top surface and a bottom surface of the cylindrical puck. The radial recess is characterized by an insulator depth extending from the top surface or the bottom surface of the puck through at least half the thickness of the puck and an insulator radius, the thermal breaker The radius is disposed symmetrically around the cylindrical axis and is at least half the radius of the puck.

In one embodiment, a method of processing a wafer includes the steps of: processing the wafer with a first process that provides a first center-to-edge process variation; and then, processing the wafer with a second process The wafer, the second process provides a second center-to-edge process variation. The second center-to-edge processing variation substantially compensates for the first center-to-edge processing variation.

In one embodiment, a workpiece holder that positions a workpiece for processing. The workpiece holder includes a substantially cylindrical positioning disc featuring a cylindrical shaft and a substantially planar top surface. The cylindrical puck defines two radial heatsinks. A first of the insulators is characterized as a radial notch that intersects a bottom surface of the locating plate with a first radius and extends from the bottom surface through the cylindrical locator At least half of the thickness of one of the discs. A second one of the heat interrupters is characterized as a radial notch that intersects the top surface with a second radius greater than the first radius and extends through the top surface at least half of the thickness of one of the pucks. A cold source substantially extends below the bottom surface of the alignment plate and includes a metal plate that flows a heat exchange fluid through channels defined therein to maintain a reference temperature for the alignment plate. A first heating device is arranged between the cooling source and the positioning plate. The first heating device is in thermal communication with the bottom surface of the positioning plate and in thermal communication with the cooling source within the first radius. A second heating device is arranged between the cooling source and the positioning plate. The second heating device is outside the second radius, in thermal communication with the bottom surface of the positioning plate and in thermal communication with the cooling source.

The present disclosure can be understood by reference to the following detailed description in conjunction with the use of the drawings described below, wherein like reference numerals are used to refer to like elements throughout the several drawings. It is noted that, for the purpose of clarity of illustration, some of the components in the drawings may not be drawn to scale. A specific instance of an item may be indicated by the use of a dash-followed reference numeral (eg, heaters 220-1, 220-2), while an unparenthesized reference numeral refers to any such item (eg, heater 220). For clarity, in instances where multiple item instances are illustrated, only certain portions of the instances may be labeled.

FIG. 1 schematically illustrates the main components of a wafer processing system 100 . System 100 is depicted as a single wafer, semiconductor wafer plasma processing system, but it will be apparent to those skilled in the art that the techniques and principles herein may be applied to any type of wafer processing system (eg, and Not necessarily processing wafers or semiconductors and not necessarily for processing systems utilizing plasma). Processing system 100 includes housing 110 for wafer interface 115 , user interface 120 , plasma processing unit 130 , controller 140 , and one or more power supplies 150 . Processing system 100 is supported by various facilities, which may include gas(s) 155, external power source 170, vacuum 160, and optionally others. For clarity of illustration, the internal plumbing and electrical connections within the processing system 100 are not shown.

Processing system 100 is illustrated as a so-called indirect plasma processing system that generates plasma at a first location and directs plasma and/or plasma products (eg, ions, molecular fragments, excited species, and the like) to the second location where the processing step occurs. Thus, in FIG. 1 , plasma processing unit 130 includes plasma source 132 that supplies plasma and/or plasma products from processing chamber 134 . The processing chamber 134 includes one or more workpiece holders 135 on which workpieces 50 (eg, semiconductor wafers, but may be different types of workpieces) to be held for processing are placed by the wafer interface 115 device 135. When the workpiece 50 is a semiconductor wafer, the workpiece holder 135 is commonly referred to as a wafer holder. In operation, the gas(s) 155 are introduced into the plasma source 132 and the radio frequency generator (RF Gen) 165 supplies power to ignite the plasma within the plasma source 132 . The plasma and/or plasma products pass from the plasma source 132 through the diffuser plate 137 to the processing chamber 134 where the workpiece 50 is processed. Alternatively or in addition to the plasma from plasma source 132 , plasma may also be ignited within processing chamber 134 for direct plasma processing of workpiece 50 .

Embodiments herein provide new and useful functionality for wafer processing systems. Significantly over the years, semiconductor wafer size has increased while feature size has decreased, so that more integrated circuits with better performance can be harvested per wafer processed. Processing smaller features while wafers grow larger requires significant improvements in processing uniformity. Because chemical reaction rates are generally temperature sensitive, temperature control across the wafer during processing is often critical to uniform processing.

Also, some types of processing may have radial effects (eg, processing that varies from the center to the edge of the wafer). Certain types of processing equipment control these effects better than others. Embodiments herein recognize that not only radial effects are important for control, but it would be further advantageous to be able to provide radial treatment control that can be tailored to compensate for treatments that cannot be so controlled. For example, consider the case where a layer is deposited on a wafer and then selectively etched away, as is common in semiconductor processing. If the deposition step is known to deposit a thicker layer at the edge of the wafer than at the center of the wafer, the compensating etch step would advantageously be at the edge of the wafer compared to the center of the wafer Provides higher etch rates so that the deposited layers are etched completely at all parts of the wafer at the same time. Similarly, if the etch process is known to have a center-to-edge variation, the compensating deposition prior to the etch process can be adjusted to provide a corresponding variation.

In the case of many processes with radial effects, a compensating process can be provided by providing a well-defined center-to-edge temperature variation, since temperature generally substantially affects the reaction rate of the process.

FIG. 2 is a schematic cross-section illustrating exemplary construction details of the workpiece holder 135 of FIG. 1 . As shown in FIG. 2 , the workpiece holder 135 comprises a substantially cylindrical puck 200 and is characterized in the sense of having a puck radius r1 in the radial direction R from the cylindrical axis Z. In use, a workpiece 50 (eg, a wafer) may be placed on the puck 200 for processing. Bottom surface 204 of puck 200 is taken to be the height of the center bottom surface of puck 200; that is, excluding features of puck 200 that may be formed as attachment points for other hardware (such as edge rings or other protrusions 206, or indentations 208) ) and in the direction of the axis Z a plane defining the general height of the bottom surface of the puck 200 . Similarly, top surface 202 is assumed to be a flat surface configured to receive workpiece 50 regardless of grooves (eg, vacuum channels, see FIG. 4 ) and/or other features that secure workpiece 50 that may be formed in the flat surface. All such protrusions, indentations, grooves, rings, etc. do not detract from the "substantially cylindrical" character of puck 200 in the context of this specification. The puck 200 may also feature in the sense of having a thickness t between the bottom surface 204 and the top surface 202, as shown. In some embodiments, the puck radius r1 is at least four times the puck thickness t, but this is not required.

The puck 200 defines one or more radial heat interrupters 210, as shown. The thermal breaker 210 is a radial notch defined in the puck 200 that intersects at least one of the top surface 202 or the bottom surface 204 of the puck 200 . The thermal breakers 210 function as their name suggests, that is, they provide thermal resistance between the radially inner portion 212 and the radially outer portion 214 of the puck 200 . This facilitates explicit radial (eg, center-to-edge) thermal control of the radially inner and outer portions of the puck 200, which is useful in providing accurate thermal matching of the inner and outer portions or deliberate temperature variations across the inner and outer portions. beneficial in the sense. Heat breaker 210 may have features in the sense of heat breaker depth and heat breaker radius. The depth of the thermal breaker 210 may vary among embodiments, but the thermal breaker depth typically exceeds one-half the thickness t. The radial positioning of the heat breaker 210 may also vary among embodiments, but the heat breaker radius r2 is typically at least one-half of the puck radius r1, and in other embodiments, r2 may be the puck radius r1 three-quarters, four-fifths, five-sixths or more. Certain embodiments may use a single heat breaker 210, while other embodiments may use two heat breakers 210 (as shown in FIG. 2) or more. The point of difference between the radially inner portion 212 and the radially outer portion 214 is shown as the radially average position between the two thermal cutouts 210 , but in embodiments with a single thermal cutoff 210 , such distinctions are The point can be considered to be the radial midpoint of the single thermal breaker 210 .

One way in which a thermal interrupter (as shown in FIG. 2 ) may be advantageously used is to provide radially applied heating and/or cooling to the inner portion 212 and outer portion 214 of the puck 200 . FIG. 3 is a schematic cross-sectional view illustrating the application of heaters and cold sources to the inner and outer portions of the puck 200 . Certain mechanical details of puck 200 are not shown in FIG. 3 for clarity of illustration. FIG. 3 shows the central channel 201 defined by the puck 200 and optional cold source 230 . The central channel 201 is described in connection with FIG. 4 . The inner heater 220 - 1 and the outer heater 220 - 2 are positioned against the puck 200 and are in thermal communication with the puck 200 . It may be advantageous for the heater 220 to diffuse across the majority of the lower surface 204, but the distribution of the heater 220 across the surface 204 may vary in embodiments. The heat provided by heater 220 will substantially control the temperature of inner portion 212 and outer portion 214 of puck 200; heatsink 210 assists in thermally isolating portions 212 and 214 from each other to improve the accuracy of thermal control. Heater 220 is typically a resistive heater, although other types of heaters may be implemented (eg, using forced gas or liquid).

An optional cold source 230 may also be provided. The cold source 230 can be controlled to exhibit a lower temperature than the normal operating temperature, for example, by flowing a heat exchange liquid through the cold source 230, or by using a cooling device such as a Peltier cooling device) to proceed. When present, cold source 230 provides several advantages. One such advantage is to provide a reference temperature that all parts of puck 200 tend to have in the absence of heat provided by heater 220. That is, although heater 220 may provide heat, such heat typically propagates through puck 200 in all directions. The cold source 230 provides the ability to drive the puck 200 to a lower temperature so that if the heater 220 is located in a particular part of the puck 200, the heat generated by the heater does not spread throughout the puck 200 not only in every direction , and heats a portion of puck 200 where heat from heater 220 locally exceeds the tendency of heat sink 230 to remove heat.

A related advantage is that the heat sink 230 can provide a rapid thermal settling effect such that when the temperature setting of the heater 220 (eg, current passing through a resistive wire) is reduced, adjacent portions of the puck 200 respond with a relatively rapid temperature reduction . This provides, for example, the benefit of being able to load workpiece 50 onto puck 200, providing heat through heater 220, and achieving rapid stabilization of the temperature on workpiece 50 so that processing can begin quickly to maximize overall system throughput . Without thermal communication to allow some heat dissipation to the heat sink 230, the temperature reached by the portion of the puck 200 would decrease only as quickly as other heat dissipation paths would allow.

In an embodiment, the heater 220 is generally disposed in direct thermal communication with the puck 200 , and the cooling source 230 is disposed in indirect thermal communication with the puck 200 through the heater 220 . Advantageously, the heat sink 230 is not in direct thermal communication with the puck 200, as such direct thermal communication can cause thermal anomalies on the surface of the puck 200 (eg, the puck 200 may have regions where the temperature changes. approach the temperature of the heat sink 230 rather than being dominated by the additional heat generated by the heater 220). Also, the heater 220 has sufficient heat generating efficiency so that the heat applied by the heater 220 can be pressed over the indirect thermal coupling between the puck 200 and the cooling source 230, so that even when some heat generated by the heater 200 is generated The heater 220 can also raise the temperature of the inner portion 212 and the outer portion 214 of the puck 200 while dissipating into the cooling source 230 . Thus, the heat provided by the heater 220 may be (but not immediately) dissipated through the cold source 230 . In embodiments, the degree of thermal coupling among puck 200, heater 220, and heat sink 230 can be adjusted in accordance with the principles herein, for example, to balance the following considerations: uniform temperature within each of the center and edge portions performance, rapidity of thermal stabilization, manufacturing complexity and cost, and overall energy consumption.

Yet another advantage of the cold source 230 is that the heat generated by the heater 220 is confined to the vicinity of the puck 200 . That is, the heat sink 230 may provide a thermal ceiling for adjacent system components to protect such components from the high temperatures generated at the puck 200 . This can improve the mechanical stability of the system and/or prevent damage to temperature sensitive components.

Heater 220 and heat sink 230 may be implemented in various ways. In one embodiment, heater 220 includes several layers coupled together as subassemblies, which layers may then be further coupled with 200 and (optionally) heat sink 230 to form a wafer holder assembly. Embodiments designed, assembled, and operated as disclosed herein allow explicit control of the temperature of the workpiece (eg, wafer) edge region relative to the center region, and facilitate processing with explicit center-to-edge temperature control that defines the center Temperature control to the edge is generally not achievable with prior art systems.

FIG. 4 is a schematic cross-sectional view of a portion of a wafer holder showing the features of the puck 200 , the resistive heater acting as the heater 220 - 1 , and the heat sink 230 . Figure 4 shows a portion of the wafer holder close to its cylindrical axis Z, and is not drawn to scale, for clarity of smaller features. The puck 200 is typically formed from an aluminum alloy, such as the well-known "6061" alloy type. The puck 200 is shown defining a surface groove or channel 205 attached to the upper surface 202 of the puck 200, and is defined as having a central channel 201 centered around the axis Z. A vacuum may be supplied to the center channel 201, reducing the pressure within the channel 205 such that atmospheric pressure (or gas pressure relative to the high pressure plasma or low pressure deposition system, eg, about 10-20 Torr) will cause the workpiece 50 (refer to FIG. 1, 2) Push against the positioning plate 200 to provide good thermal communication between the positioning plate 200 and the workpiece 50 .

The inner resistive heater 220-1 is shown in FIG. 4, but it should be understood that the description of the inner resistive heater 220-1 and the following description apply equally to the outer resistive heater 220-2. Resistive heater 220 - 1 includes heater traces 264 and buffer layer 266 . The heater traces 264 are illustrated in FIG. 4 as a continuous layer, but are understood to exist as layers forming a serpentine pattern to distribute heat evenly along their length (ie, the heater traces 264 become along the lines of FIG. 4 . The cross-sectional planes shown in, but in other cross-sectional views, intermittently intersecting cross-sectional planes, see Figure 5). Heater traces 264 may be formed, for example, with Inconel in a thickness of about 0.0005" to 0.005", although layers of about 0.0002" to 0.02" are also useful, as are other material choices. The buffer layer 266 is typically a polymer layer of about 0.025" to 0.10" thick, although layers of about 0.01" to 0.15" are also useful. The buffer layer 266 may be formed of polyimide, although other polymers and other material choices may be useful. The buffer layer 266 is preferably a thermally stable electrical insulator (to avoid shorting the heater traces 264). The buffer layer 266 is also preferably compressible so that when coupled with the much thinner heater traces 264, the opposite side of the buffer layer 266 is approximately planar for mechanical purposes. In addition, the buffer layer 266 increases the thermal resistance between the heater track layer 264 and the heat sink 230 , so that when the heater track layer 264 supplies heat, more heat is transferred to the puck than to the heat sink 230 . 200.

In an embodiment, heater trace layer 264 and buffer layer 266 are coupled within thin metal layers 260, 268 that help diffuse uniformly from heater trace layer 264 across the surface of heater 220-1 hot. Thin, electrically insulating layer 262 is included to keep metal layer 260 from shorting out heater trace layer 264; insulating layer 262 or insulating layer 266 may also serve as a substrate for making heater trace layer 264 (see Figure 5) . The insulating layer 262 is preferably a thermally stable material, may be formed from a ceramic or polymer (eg, polyimide), and in embodiments has a thickness of about 0.001" to 0.040". The metal layers 260, 268 may be, for example, layers of Al 6061 of about 0.005" to 0.050". Metal layers 260 , 268 also provide moderate protection to layers 262 , 264 and 266 so that heater 220 - 1 can be fabricated and shipped as a subassembly for later integration with puck 200 and heat sink 230 . For example, layers 260, 262, 264, 266, 268, and 270, shaped to desired dimensions, can be positioned and aligned with each other into a stack and bonded by compressing and/or heating the stack to form heater 220-1 as Subassembly. It will be apparent to those skilled in the art after reading and understanding the above disclosure that the heater sub-assemblies as disclosed herein will be generally planar, and for wafer holder applications will be generally circular , but similarly fabricated subassemblies need not be circular, and can be fabricated to conform to differently shaped surfaces (eg, square, rectangular, etc.) than the circular bottom surface of the cylindrical puck described herein ). Similarly, while heater tracks for cylindrical pucks can be arranged for azimuthal uniformity and uniform heating density, the heater tracks within the sub-assemblies can then be arranged to form locally intense and less intense heating patterns.

Heater 220-1 is coupled to puck 200 through optional layer 250, and to heat sink 230 through a further optional layer 270, as shown. Layers 250 and 270 facilitate heat transfer between heater 220-1 and both puck 200 and heat sink 230; material choices for layers 250 and 270 include thermally stable polymers. In one embodiment, the optional layers 250, 270 are formed as polymer layers having a substantial thermal conductivity of about 0.22 W/(m-K). Layers 250 and/or 270 may also be bonded to puck 200 and layer 260 and heat sink 230 and layer 268, respectively, such that puck 200, heat sink 230 and heaters 220-1 and 220-1 may be bonded together. To accomplish this, puck 200, layer 250, heaters 220-1 and 220-2, layer 270, and heat sink 230 can all be positioned in alignment with each other and bonded by compression and/or heating.

In an embodiment, the heat sink 230 provides a reference temperature for the puck 200 while still allowing the inner and outer resistive heaters 220 - 1 and 220 - 2 to provide center-to-edge temperature control for the puck 200 . The temperature of the optional cold source 230 may be actively controlled. For example, FIG. 4 illustrates cooling sources 230 defining fluid channels 280 through which heat exchange fluid can be forced. The heat sink 230 may also form heat sinks 290 to increase the contact area and thus increase the heat exchange efficiency of the fluid within the channel 280 . In this context, "heat exchange fluid" is not necessary, the mixture always cools the heat sink 230; the heat exchange fluid can add or remove heat. The heat exchange fluid may be provided at a controlled temperature. In one embodiment, heat sink 230 is formed from an aluminum alloy (eg, "6061" type), and the heat exchange fluid is a mixture of 50% ethylene glycol and 50% water, although other materials may be used for heat sink 230 and/or heat exchange fluid. In yet other embodiments, the optional cooling 230 may be a passive cooling source, eg, the cooling source 230 may be a passive heat sink, and may have heat sinks, etc., to dissipate heat to the surrounding environment.

FIG. 5 schematically illustrates the layout of the heater traces 264 on the insulating layer 262 . The additional placement of heater tracks 264 is not critical, but ideally the placement is dense and azimuthally uniform. Heater traces 264 may terminate in pairs of bond pads 274, as shown, for later connection to wires supplying power. As shown in FIG. 5, the heater traces 264 do not necessarily extend into the central region 269 of the inner resistive heater 220-1. One reason for this is that the temperature reached within the puck 200 in the area of the surrounding area 269 will spread rapidly across the corresponding area of the puck 200 . Another reason is that it may be desirable to keep region 269 open for other purposes, such as providing vacuum passages 201 (see FIGS. 3, 4 ), fluid connections for heat exchange fluids, electrical power for heater tracks 264 contacts and/or other features.

A further advantage of providing at least one thermal cutout 210 that intersects the top surface of the puck 200 is that mechanical features can be at least partially disposed within the thermal cutout such that the features do not create thermal anomalies. For example, wafer holders typically provide lift pins that can be used to lift the wafer a short distance from the holder to facilitate access by wafer handling tools (typically used to insert into the wafer after the wafer is raised) and vanes or other devices between the clamps). However, lift pins are typically retracted into holes in the fixture, and such holes can locally affect wafer temperature during processing. When the thermal breaker intersects the top surface of the puck 200, there is already a place for such a mechanism to be placed without causing thermal anomalies.

FIG. 6 schematically shows that the wafer holder has a portion of the lift pin mechanism 300 that controls the lift pins 310 , which are positioned within the heat breaker 210 . Portions of heater 220 and optional cooling source 230 are also shown. The cross-sectional plane depicted in FIG. 6 passes through the center of the mechanism 300 with its elements within the lower portion of one 210 . In and out of the plane shown, the puck 200, the heatsink 210, and the heat sink 230 may have contours similar to those shown in Figures 3 and 4, such that the heatsink 210 will pass through the puck 200 along the The arc length of the thermal breaker 210 in which the mechanism 300 is housed is continued (see FIG. 7 ). Also, the lift pin mechanism 300 is limited to a relatively small azimuth angle with respect to the central axis of the positioning plate 200 (refer to FIG. 7 ). That is, if a cross-sectional plane is taken at a certain distance to the inside or outside of the plane shown in FIG. 6, the bottom surface of the puck 200 will be continuous along the same plane as the bottom surface 204 indicated in FIG. 200 will be continuous. The small size of the lift pin mechanism 300 limits thermal deflection of the puck 200 in the area of the lift pin mechanism 300 . FIG. 6 illustrates the lift pin 310 in a retracted position, where it will not create thermal anomalies on the surface of the puck 200 .

FIG. 7 schematically depicts three lift pin arrangements in a plan view, wherein lift pins 310 are disposed within the heat breaker 210 . FIG. 7 is not drawn to scale, in particular, the heat breaker 210 is exaggerated to clearly illustrate the lift pin mechanism 300 and lift pins 310 . Because the lift pins 310 retract well below the average surface of the puck 200 into the heat insulator 210, the lift pins 310 do not generate thermal anomalies in the space during processing, so that the portion of the workpiece being processed at the position of the lift pins 310 ( Certain integrated circuits, such as those located at corresponding locations on a semiconductor wafer, undergo processing that is consistent with processing elsewhere on the workpiece.

8 is a flow diagram of a method 400 for processing wafers or other workpieces (hereinafter referred to for convenience as "product wafers" with the understanding that the concepts can be applied to workpieces other than wafers). The method 400 can be enabled solely by the thermal management device described in connection with FIGS. 2-8, which can be used to provide explicit center-to-edge thermal control, which in turn allows explicit center-to-edge process control. A first step 420 of method 400 processes a product wafer with a first center-to-edge processing variation. The second step 440 of method 400 processes the product wafer with a second center-to-edge processing variation that compensates for the first center-to-edge variation. In general, one of 420 or 440 will be implemented in a device or in a processing environment where associated center-to-edge processing changes (hereinafter "uncontrolled changes") are inadvertently or uncontrollably generated or the other, but this is not necessary. And, in general, the other is implemented in an apparatus such as the one described herein, such that another center-to-edge processing variation is induced through thermal management techniques that allow explicit control of the center and edge portions of the product wafer ( hereinafter referred to as "controlled changes") to provide corresponding, inverse process changes. However, uncontrolled changes and controlled changes can occur in either order. That is, 420 may cause uncontrolled or controlled changes, while 440 may cause the other of uncontrolled and controlled changes. 9 and 10 provide additional guidance to those skilled in the art to allow method 400 to be usefully performed.

FIG. 9 is a flowchart of a method 401 including, but not limited to, step 420 of the method 400 . All of 410-418 and 422 shown in FIG. 9 are considered optional (but may be helpful in embodiments) in performing method 400 to achieve useful wafer processing results.

Step 410 sets the device characteristics for the first center-to-edge processing change that will occur at 420 . For example, where it is desired 420 to cause a controlled change, 410 may involve providing device parameters, such as set for a heater, that will provide a controlled center-to-edge temperature change. Devices as described herein in Figures 2-7 are useful in providing controlled center-to-edge temperature variation. Step 412 measures device characteristics with respect to the first center-to-edge process variation. Process knowledge can be acquired over time as to which of the device settings (or measured device characteristics) are successful (or at least provide stable, albeit unintentional) process changes in producing known center-to-edge process changes. When considering this process knowledge, method 401 may optionally return from 412 to 410 to adjust the device characteristics if the device characteristics measured in 412 may be improved. Step 414 processes the one or more test wafers receiving the first center-to-edge processing variation. Step 416 measures one or more characteristics of the first center-to-edge process variation on the test wafer processed in step 414 . Method 401 may optionally return from 416 to 410 to adjust device characteristics based on the center-to-edge processing characteristics measured in 416 . Any wafers processed in 414 may optionally be stored in 418 for testing in a second process (eg, a process to be performed later in 440). Also, 414 may be performed in parallel with 420 . That is, when the processing equipment is properly configured, the test wafers can be processed simultaneously with the production wafers (e.g., if the first process is a so-called "batch" process, such as dipping the wafer cassette into a liquid bath, process a collection of wafers together in ampoules, diffusion furnaces or deposition chambers, etc.).

Step 420 processes the product wafer with a first center-to-edge processing variation. Step 422 measures one or more first center-to-edge characteristics on the production wafer to generate data for equipment process control purposes, data for the yield or performance of the associated production wafer, and/or for The data surrounding the information of step 440 is associated, as described further below.

FIG. 10 is a flowchart of a method 402 that includes, but is not limited to, step 440 of the method of FIG. 400 . All of 430-436 and 442 shown in FIG. 10 are considered optional (but may be helpful in embodiments) in performing method 400 to achieve useful wafer processing results.

Step 430 sets the device characteristics for the second center-to-edge processing change that would occur at step 440 . For example, where 440 is desired to cause a controlled change, 430 may involve providing device parameters, such as set for a heater, that will provide a controlled center-to-edge temperature change. Devices as described herein in Figures 2-7 are useful in providing controlled center-to-edge temperature variation. Step 432 measures device characteristics with respect to the second center-to-edge processing variation. In considering process knowledge, as discussed above, method 402 may optionally return from 432 to 430 to adjust device characteristics as a function of the device characteristics measured in 432 . Step 434 processes the one or more test wafers receiving the second center-to-edge process variation; the test wafers processed in 434 may include the one or more test wafers from the first process step stored in 418 described above . Step 436 measures one or more characteristics of the second center-to-edge process variation on the test wafer processed in 434 . Method 402 may optionally return from 436 to 430 to adjust device characteristics based on the center-to-edge processing characteristics measured in 436 while considering previously acquired processing knowledge.

Step 440 processes the product wafer with a second center-to-edge processing variation. Also, although not shown in method 402, additional test wafers may of course be processed in parallel with the production wafers. Step 442 measures one or more first center-to-edge characteristics on the product wafer to generate data for equipment process control purposes, data for the yield or performance of the associated product wafer, and/or for Data associated with information surrounding 420, as described above. Such measurements may also be performed on any test wafer, but in any event, 442 will generally not further alter any conditions presented on the production wafer. That is, the results of 420 and 440 will be fixed in the production wafer at the end of 440, regardless of any further testing done.

Having described several embodiments, it will be recognized by those skilled in the art that various modifications, alternative constructions, and equivalents may be utilized without departing from the spirit of the invention. Furthermore, many well-known processes and components have not been described in order to avoid unnecessarily obscuring the present invention. Accordingly, the above description should not be construed as a limitation of the present invention.

Processing workpieces other than wafers may also benefit from improved process uniformity and is considered within the scope of this disclosure. Therefore, the feature herein that a gripper has a "wafer gripper" for holding a "wafer" should be understood as equivalent to a gripper for gripping any kind of workpiece, and a "wafer handling system" is understood as Similarly equivalent to the processing system.

Where a range of values is provided, it is understood that each intervening value (up to ten times the unit of the lower limit, unless the context clearly dictates otherwise) between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in that stated range is included. The upper and lower limits of these smaller ranges may independently be included or excluded from the range, and ranges including any, excluding, or both limits are also encompassed within the invention, Subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of the included limits are also included.

As used herein and in the appended claims, the singular forms "a (a)," "an (an)," and "the (the)" include plural referents unless the context clearly dictates otherwise. . Thus, for example, reference to "a process" includes a plurality of such processes, and reference to "the electrode" includes reference to one or more electrodes and equivalents thereof known to those skilled in the art allegation, and so on. Also, the words "comprise", "comprising", "include", "including" and "includes" when used in this specification and in the claims below , are intended to specify the presence of stated features, integers, elements or steps, but they do not preclude the presence or addition of one or more other features, integers, elements, steps, acts or groups.

50‧‧‧Workpiece 100‧‧‧Wafer Handling System 110‧‧‧Enclosure 115‧‧‧Wafer Interface 120‧‧‧User Interface 130‧‧‧Plasma Processing Unit 132‧‧‧Plasma Source 134‧‧‧Processing chambers 135‧‧‧Workpiece holder 137‧‧‧Diffusion plate 140‧‧‧Controller 150‧‧‧Power 155‧‧‧Gas 160‧‧‧Vacuum 165‧‧‧RF generator 170‧‧‧External power supply 200‧‧‧Locating disc 201‧‧‧Central Channel 202‧‧‧Top 204‧‧‧Bottom 205‧‧‧Surface grooves or channels 206‧‧‧Protrusion 208‧‧‧Dent 210‧‧‧Radial Heat Cutters 212‧‧‧Radial inner part 214‧‧‧Radial outer part 220-1‧‧‧Inner heater 220-2‧‧‧External heater 230‧‧‧Cold source 250‧‧‧optional layers 260‧‧‧Thin metal layers 262‧‧‧Insulation 264‧‧‧Heater trace layer 266‧‧‧Buffer layer 268‧‧‧Thin metal layers 269‧‧‧Central area 270‧‧‧Optional layers 274‧‧‧Bond pads 280‧‧‧Fluid channel 290‧‧‧ Heat sink 300‧‧‧Lifting pin mechanism 310‧‧‧Lifting pin 400‧‧‧Method 401‧‧‧Method 402‧‧‧Method 410‧‧‧Steps 412‧‧‧Steps 414‧‧‧Steps 416‧‧‧Steps 418‧‧‧Steps 420‧‧‧First Step 422‧‧‧Steps 430‧‧‧Steps 432‧‧‧Steps 434‧‧‧Steps 436‧‧‧Steps 440‧‧‧Second Step 442‧‧‧Steps r1‧‧‧Locating disc radius r2‧‧‧Radius of heat-breaker R‧‧‧Radial direction t‧‧‧Thickness of positioning plate Z‧‧‧cylindrical shaft

Figure 1 schematically illustrates the main components of a processing system with a workpiece holder according to an embodiment.

FIG. 2 is a schematic cross-sectional view illustrating exemplary construction details of the workpiece holder of FIG. 1 .

FIG. 3 is a schematic cross-sectional view illustrating the application of heaters and cold sources to the inner and outer portions of the puck, the integrated portions forming part of the workpiece holder of FIG. 1 , according to one embodiment.

FIG. 4 is a schematic cross-sectional view illustrating features of a puck, a resistive heater, and a cooling source, according to one embodiment.

FIG. 5 schematically illustrates the layout of heater tracks within the resistive heater of FIG. 4 , according to one embodiment.

According to an embodiment, FIG. 6 schematically illustrates a lift pin mechanism disposed in a heat breaker.

According to an embodiment, FIG. 7 schematically depicts three lift pin arrangements in a plan view, wherein the lift pins are disposed within the heat breaker.

8 is a flow diagram of a method for processing wafers or other workpieces, according to one embodiment.

FIG. 9 is a flowchart of a method including, but not limited to, a step of the method of FIG. 8 .

FIG. 10 is a flowchart of a method including, but not limited to, another step of the method of FIG. 8 .

Domestic storage information (please note in the order of storage institution, date and number) None

Foreign deposit information (please note in the order of deposit country, institution, date and number) None

(Please change the page and record it separately) None

200‧‧‧Locating disc

201‧‧‧Central Channel

205‧‧‧Surface grooves or channels

220-1‧‧‧Inner heater

230‧‧‧Cold source

250‧‧‧optional layers

260‧‧‧Thin metal layers

262‧‧‧Insulation

264‧‧‧Heater trace layer

266‧‧‧Buffer layer

268‧‧‧Thin metal layers

270‧‧‧Optional layers

280‧‧‧Fluid channel

290‧‧‧ Heat sink

R‧‧‧Radial direction

Z‧‧‧cylindrical shaft

Claims (27)

A workpiece holder for positioning a workpiece for processing, the workpiece holder comprising: a substantially cylindrical positioning disk characterized by a cylindrical shaft, a positioning disk radius around the cylindrical shaft, and a positioning disk thickness, wherein the The puck radius is at least four times the puck thickness, wherein at least one top surface of the cylindrical puck is substantially planar, and wherein the cylindrical puck defines one or more radial heat interrupters, each breaking Heater is characterized as a radial notch that intersects at least one of the top surface and a bottom surface of the cylindrical puck, wherein the radial notch is characterized as: a thermal break a depth of the spacer extending from the top surface or the bottom surface of the puck through at least half the thickness of the puck, and an insulator radius, symmetrically positioned around the cylindrical axis and at least half the radius of the puck, And wherein the radial notch intersects the top surface, the workpiece holder further includes at least three lifting members, the at least three lifting members extend above the top surface in an extended state to lift from the top surface. The workpiece is lifted, and the at least three lifting members are retracted into the radial recess in a retracted state to lower the workpiece to the top surface. The workpiece holder of claim 1, wherein the radial The notch feature is a heat breaker radius that is at least 60% of the puck radius. The workpiece holder as claimed in claim 1, further comprising: a first heating device disposed near the bottom surface of the positioning plate and radially inward from the one or more heat insulators relative to the cylindrical axis Arranged, the first heating device is in thermal contact with the bottom surface of the puck within the radius of the thermal breaker, and a second heating device is positioned near the bottom surface of the puck and is separated from the one or more interrupters Heaters are disposed radially outwardly relative to the cylindrical axis, and the second heating device is in thermal contact with the bottom surface of the puck outside the heatsink radius. The workpiece holder of claim 3, wherein at least one of the first and second heating devices includes a heater member trace disposed within a plurality of electrically insulating layers. A workpiece holder for positioning a workpiece for processing, the workpiece holder comprising: a substantially cylindrical positioning disc characterized by a cylindrical shaft, a positioning disc radius around the cylindrical shaft, and a positioning disc thickness, wherein: The puck radius is at least four times the puck thickness, at least one top surface of the cylindrical puck is substantially planar, and the cylindrical puck defines one or more radial thermal insulators, each thermal insulator is characterized as a radial notch that intersects in at least one of the top surface and a bottom surface of the cylindrical puck, wherein the radial recess is characterized by a thermal breaker depth extending from the top surface or the bottom surface of the puck through the puck At least half of the thickness of the plate, and a radius of a heat breaker, arranged symmetrically around the cylindrical axis, and at least half of the radius of the positioning plate; a first heating device, arranged near the bottom surface of the positioning plate, and from The one or more thermal cutouts are disposed radially inward with respect to the cylindrical axis, the first heating device is in thermal contact with the bottom surface of the puck within the radius of the thermal cutoff, and a second heating device is disposed near the bottom surface of the puck and disposed radially outward from the one or more heatsinks with respect to the cylindrical axis, the second heating device is outside the radius of the heatsink and the bottom surface of the puck thermally contacting, wherein: at least one of the first and second heating devices includes a heater member trace disposed within a plurality of electrically insulating layers, the heater member trace including a resistive material, and At least one of the electrically insulating layers includes polyimide. The workpiece holder of claim 5, wherein the heater member traces and the electrically insulating layers are disposed within a plurality of metal layers. The workpiece holder of claim 5, wherein the radial The notch feature is a heat breaker radius that is at least 60% of the puck radius. A workpiece holder for positioning a workpiece for processing, the workpiece holder comprising: a substantially cylindrical positioning disc characterized by a cylindrical shaft, a positioning disc radius around the cylindrical shaft, and a positioning disc thickness, wherein: The puck radius is at least four times the puck thickness, at least one top surface of the cylindrical puck is substantially planar, and the cylindrical puck defines one or more radial thermal insulators, each thermal insulator is characterized as a radial notch that intersects at least one of the top surface and a bottom surface of the cylindrical puck, wherein the radial notch features: a thermal cutout a depth extending from the top surface or the bottom surface of the puck through at least half of the puck thickness, and a heat breaker radius symmetrically positioned around the cylindrical axis and at least half the puck radius; a a first heating device disposed near the bottom surface of the puck and disposed radially inward from the one or more thermal cutouts relative to the cylindrical axis, the first heating device being within a radius of the thermal cutoff to The bottom surface of the puck is in thermal contact, and a second heating device is positioned near the bottom surface of the puck and is distributed radially outward from the one or more heatsinks relative to the cylindrical axis the second heating device is in thermal contact with the bottom surface of the puck outside the radius of the heat breaker; and a cold source extending substantially across the bottom surface of the cylindrical puck, the first and second heating devices are disposed between the cold source and the bottom surface of the cylindrical positioning plate. The workpiece holder of claim 8, wherein the heat sink comprises a metal plate defining one or more fluid passages. The workpiece holder of claim 8, wherein: the first and second heating devices include respective first and second heater member tracks disposed between the first and second electrically insulating layers; the first and second heating means An electrical insulating layer is disposed between the first and second heater member tracks and the heat sink; the second electrical insulating layer is disposed between the first and second heater member tracks and the bottom surface of the cylindrical positioning plate and the first electrical insulating layer is thicker than the second electrical insulating layer, so that the first electrical insulating layer increases the thermal resistance between the heater component traces and the heat sink, so that in the heater component traces When supplying heat, a larger portion of the heat is transferred to the puck than to the cooling source. The workpiece holder of claim 10, wherein the first of the electrically insulating layers comprises ceramic. The workpiece holder of claim 10, further comprising: first and second metal layers; and first and second thermally stable polymer layers; and wherein the workpiece holder is bonded together, having a plurality of elements and layers arranged from bottom to top in the following physical order: the cold source; the first thermally stable polymer layer; the first metal layer; the first electrically insulating layer; the first and second heater member traces, at the same level, the second heater member trace from the first A heater member traces radially outward; the second electrically insulating layer; the second metal layer; the second thermally stable polymer layer; and the puck. The workpiece holder of claim 8, wherein the cylindrical alignment plate defines two of the radial heat interrupters; a first of the radial heat interrupters is characterized by an intersection at the cylindrical a radial notch in the top surface of the puck, the depth of the thermal breaker of the first of the radial thermal breakers extending down from the top face of the puck through more than half of the puck thickness ; and a second of the radial insulators is characterized by an intersection on the circle The radial recess of the bottom surface of the cylindrical puck, the cutoff depth of the second of the radial heat interrupters extends upwardly from the bottom surface of the puck through more than half of the puck thickness. A method of processing a wafer, comprising the steps of: processing the wafer with a first process that provides a first center-to-edge process variation; and then, processing the wafer with a second process, the The second processing provides a second center-to-edge processing variation; wherein the second center-to-edge processing variation substantially compensates for the first center-to-edge processing variation. The method of processing a wafer of claim 14, wherein: the step of processing the wafer with the first process comprises the steps of: depositing a material layer on the wafer; the first center-to-edge change is the a thickness variation in a thickness of a layer of material; the step of treating the wafer with the second process comprises the steps of: etching the layer of material in at least selected regions of the wafer; and the second center-to-edge variation is An etch rate is varied such that the material layer is etched through in at least the selected regions of the wafer for an etch time that is substantially constant from the center to the edge of the wafer. The method of processing a wafer of claim 14, wherein: the step of processing the wafer with at least one of the first process and the second process comprises the step of: establishing a center-to-edge across the wafer temperature change. A method of processing a wafer as claimed in claim 16, wherein the step of establishing the center-to-edge temperature variation across the wafer comprises the steps of placing the wafer in thermal communication with a top surface of a cylindrical puck, The cylindrical puck is characterized by a radius and a puck thickness between a top surface and a bottom surface of the cylindrical puck; and using a center region of the puck and an edge region of the puck At least one of the heaters is in thermal communication to establish the center-to-edge temperature variation. A method of processing a wafer as recited in claim 17, wherein the step of establishing the center-to-edge temperature variation across the wafer further comprises the step of providing the puck with at least one radial notch, the at least one radial The notch intersects at least one of the top surface and the bottom surface, the at least one radial notch acts as a heat insulator between the edge region of the puck and the center region of the puck, wherein the diameter Toward the notch is characterized by an insulator depth, the insulator The depth extends from the top surface or the bottom surface of the puck through at least half the thickness of the puck. The method of processing a wafer of claim 18, wherein the step of establishing the center-to-edge temperature variation across the wafer further comprises the step of: providing the at least one radial notch with a radius of the At least three quarters of the radius of the cylindrical puck. The method of processing a wafer of claim 17, wherein the heater is a first heater in thermal communication with the center region of the puck, and wherein: the center-to-edge temperature variation is established across the wafer The step of further includes the step of: providing a second heater in thermal communication with the edge region of the puck. The method of processing a wafer of claim 17, wherein the step of establishing the center-to-edge temperature variation across the wafer further comprises the step of: providing a heat sink in thermal communication with the first and second heaters . A method of processing a wafer as recited in claim 17, wherein the step of establishing the center-to-edge temperature variation across the wafer further comprises the step of flowing a heat exchange liquid through the cooling unit at a controlled temperature Fluid channels within the source. A workpiece holder for positioning a workpiece for processing, the workpiece holder comprising: a substantially cylindrical positioning disk characterized by a cylindrical shaft and a substantially planar top surface, wherein the cylindrical positioning disk defines two diameters Towards the thermal interrupters, a first of the thermal interrupters is characterized as a radial notch that intersects and extends from a bottom surface of the puck with a first radius through at least half of a thickness of the locating disc; a second one of the heat interrupters is characterized as a radial notch intersecting at a second radius greater than the first radius the top surface, extending from the top surface through at least half of a thickness of the positioning plate; a cooling source extending substantially below the bottom surface of the positioning plate, the cooling source comprising a metal plate, the metal plate attaching a a heat exchange fluid flows through channels defined therein to maintain a reference temperature for the puck; a first heating device disposed between the cold source and the puck, the first heating device within the first radius , in thermal communication with the bottom surface of the positioning plate and with the cold source; and a second heating device, arranged between the cold source and the positioning plate, the second heating device is outside the second radius, and the positioning disc The bottom surface is in thermal communication with the cold source. The workpiece holder of claim 23, wherein: the first and second heating means include respective first and second heater member tracks disposed between the first and second electrically insulating layers. The workpiece holder of claim 24, wherein: the first electrical insulating layer is disposed between the first and second heater member traces and the heat sink; the second electrical insulating layer is disposed on the first and the second heater member track and the bottom surface of the cylindrical puck; and the first electrical insulating layer is thicker than the second electrical insulating layer, so that the first electrical insulating layer increases the heater member tracks and the The thermal resistance between the heat sinks is such that when the heater member traces supply heat, a greater portion of the heat is transferred to the puck than to the heat sink. The workpiece holder of claim 24, wherein the first of the electrically insulating layers comprises ceramic. : The workpiece holder of claim 24, further comprising: first and second metal layers; and first and second thermally stable polymer layers; and wherein the workpiece holder is bonded together having a plurality of elements and layers are configured from bottom to top in the following physical order: the cold source; the first thermally stable polymer layer; the first metal layer; the first electrically insulating layer; the first and second heater member traces, at the same level, the second heater member trace heating from the first the second electrically insulating layer; the second metal layer; the second thermally stable polymer layer; and the puck.

Images