JP2000058296A - Plasma treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma treatment device having good uniformity. SOLUTION: This plasma treatment device is equipped with a vacuum chamber 2+3 in which a plasma space 5 is formed, a plurality of induction coupling elements 21-24 installed at the vacuum chamber, and a power supply means 2 to impress a high frequency wave on these coupling elements, wherein the arrangement further includes power adjusting means 40-48 which are installed in or on the high frequency line and adjust the power distributed to the elements 21-24 and mutual interference reducing means 32-34 installed or formed between the elements 21-24. Through reduction of mutual interference of the elements and heightening of the independency, the controllability in each local place for the electromagnetic field distribution is enhanced and the plasma density distribution in the plasma space 5 is made uniform.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus suitable for performing plasma processing such as etching, film formation, and ashing in a high-precision manufacturing process such as an IC or LCD.

[0002]

2. Description of the Related Art A plasma processing apparatus shown in FIG. 9A is a schematic longitudinal sectional view of a main part, which comprises a vacuum chamber body 2 and a vacuum chamber lid 3, etc., and has a plasma processing space 5 inside.
A vacuum chamber in which a (plasma space) is formed, a coil unit 10 attached to the vacuum chamber, and an RF power supply 12 (power supply means) for applying a high frequency to a coil 11 (inductive coupling element) of the coil unit 10. It is provided with. A through-hole 2a, a through-hole 2b, and the like are formed in the vacuum chamber body 2, and a vacuum pump 6 for securing a vacuum pressure suitable for plasma maintenance and a gas (not shown) for supplying an appropriate processing gas required for plasma processing, respectively. Units and the like are connected. In the plasma processing space 5 in the vacuum chamber, a cathode section 4 on which the workpiece 1 is mounted is installed.
Is supported by a support 4a implanted on the inner bottom of the, and is connected to the RF power source 7 via a blocking capacitor 7a.

[0003] The workpiece 1 is carried into the cathode section 4 through a through-hole with a gate (not shown), and when the plasma processing space 5 reaches a predetermined gas pressure or the like, the RF processing is performed.
When a high frequency is applied from the power supply 12 to the coil 11, the gas in the plasma processing space 5 is excited by the alternating electromagnetic field generated from the coil 11, and plasma is generated and formed there. Thus, the upper surface of the processing target 1 is exposed to the plasma, and the plasma processing is performed on the processing target 1. At this time, if the RF power supply 7 is also operated, anisotropy is given to the plasma processing.

In order to improve the uniformity of such plasma processing, a plasma processing apparatus in which the coil unit 10 is composed of a plurality of coils 11 and a variable capacitor 13 is connected to each coil as current adjusting means is also known. It is known (see JP-A-8-50998). This is to increase the magnetic flux density by connecting a plurality of coils in parallel, and to obtain a uniform magnetic flux density distribution by adjusting the current flowing through each coil 11.

When the plasma is generated, the equipotential lines 14 and the magnetic flux density distribution generated in the plasma processing space 5 are as follows:
It becomes uniform as such (see FIG. 9B). However,
After the low-temperature plasma 15 is generated in the plasma processing space 5, the situation is different. Often a part of low-temperature plasma 15
The plasma high-concentration portion 16 is generated locally (see FIG. 9).
As a result, it is difficult to ensure the uniformity of the plasma processing that matches the uniformity of the equipotential lines 14 and the like.

[0006]

Of course, it is also possible to make further adjustments to the current of each coil by using current adjusting means so as to suppress local high-concentration portions of the plasma. However, in the above-described conventional plasma processing apparatus, the electromagnetic fields generated from the coils at different installation positions are superimposed on each other to obtain uniformity of the electromagnetic field in the plasma processing space. The electromagnetic fields from the coils interfere with each other in the space.

[0007] On the other hand, plasma has a characteristic that the higher the concentration of ions, the higher the degree of electromagnetic coupling is in the high concentration portion, so that the high concentration portion of the plasma becomes increasingly dense and the plasma density distribution becomes uneven. Therefore, simply adjusting the current of the coil close to the high-concentration portion of the plasma leaves an electromagnetic field from another coil such as an adjacent coil, absorbing the energy and maintaining the high-concentration portion of the plasma. On the other hand, if the current was adjusted for a plurality of coils that could interfere with each other, it is possible to make it difficult for plasma to be generated near those coils, but conversely, plasma was likely to be generated around those coils. As a result, only the high-concentration portion of the plasma is moved, and the uniformity is not improved at all.

Therefore, in supplying energy to plasma using a plurality of inductive coupling elements, it is important to find out how to secure a high degree of uniformity of plasma density distribution which cannot be obtained by pursuing uniformity of an electromagnetic field. This is a technical issue. The present invention has been made to solve such a problem, and has as its object to realize a plasma processing apparatus having good uniformity.

[0009]

Means for Solving the Problems First to sixth solving means invented to solve such problems are as follows.
The configuration and operation and effect will be described below.

[First Solution] A plasma processing apparatus according to a first solution (as described in claim 1 at the beginning of the application) includes a vacuum chamber in which a plasma space is formed and a vacuum chamber attached to the vacuum chamber. A plurality of inductive coupling elements and power supply means for applying a high frequency to the plurality of inductive coupling elements, wherein the plurality of inductive coupling elements are provided by interposing or adding to the high frequency line. Power adjusting means for adjusting the power distributed to the coupling element;
Mutual interference reducing means provided or formed between the plurality of inductive coupling elements.

[0011] In the plasma processing apparatus of the first solution, mutual interference between the inductive coupling elements is prevented or reduced by the interposition of the mutual interference reducing means. When the power of the coupling element is adjusted, there is no or little influence from other inductive coupling elements such as adjacent elements, so that the amount of energy supplied to the high-concentration part of the plasma is quickly reduced. On the other hand, with respect to the plasma having a low concentration such as around the high-concentration portion, the energy supply from other inductive coupling elements is continued without being affected by the local power adjustment.

As described above, the mutual interference of the plurality of inductive coupling elements is reduced to increase the independence, so that the local controllability of the electromagnetic field distribution is improved even if the uniformity of the electromagnetic field distribution is somewhat lost. As a result, the occurrence of local high-concentration portions of the plasma can be accurately suppressed, so that the plasma is distributed at a uniform density in the plasma space. Therefore, according to the present invention, a plasma processing apparatus with good uniformity can be realized.

[Second Solution] The plasma processing apparatus of the second solution is the plasma processing apparatus of the first solution, wherein: The mutual interference reducing means is an extension of the plasma space extending between the plurality of inductive coupling elements.

[0014] In the plasma processing apparatus of the second solution, the energy of the electromagnetic field whose propagation is blocked by the mutual interference reducing means, that is, the expansion of the plasma space, is reduced by the plasma in the expansion of the plasma space. Is absorbed by Thus, the power applied to the inductive coupling element is
Almost all is supplied to the plasma without being wasted by the mutual interference reducing means. Therefore, according to the present invention, a plasma processing apparatus having good energy efficiency in addition to uniformity can be realized.

[Third Solution] The plasma processing apparatus of the third solution (as described in claim 3 at the beginning of the application) is the plasma processing apparatus of the first and second solutions. And a power distribution state detecting means for detecting a distribution state of the electric power supplied to the plasma space.

[Fourth Solution] The plasma processing apparatus according to the fourth solution (as described in claim 4 at the beginning of the application) is the plasma processing apparatus according to the third solution, wherein The power adjusting means adjusts the power based on the detection by the power distribution state detecting means.

In the plasma processing apparatus according to the third and fourth solutions, when a locally high-concentration portion is generated in the plasma space, the degree of coupling between the high-concentration portion and the inductive coupling element close to the portion is reduced. And the power to the inductive coupling element increases,
The change in the power distribution state is detected by the power distribution state detection means, and the power distribution means adjusts the distribution power to the plurality of inductive coupling elements based on the detection.

As a result, the power to each inductive coupling element is adjusted at each location so as to offset or mitigate the local plasma density fluctuation, and appropriate feedback control is automatically performed. Therefore, even if the state of the plasma changes due to sudden change or conscious switching of the type and flow rate of the processing gas or the gas pressure, the uniformity of the plasma is reliably ensured. It will be. Therefore, according to the present invention, it is possible to always realize a plasma processing apparatus having good uniformity.

[Fifth Solution Means] The plasma processing apparatus of the fifth solution means (as described in claim 5 at the time of filing the application) is the plasma processing apparatus of the first to fourth solution means. The power adjusting means varies the inductance of the high-frequency line.

In the plasma processing apparatus according to the fifth solution, when the inductance is changed, not only the current flowing through the inductive coupling element connected to the line but also the applied voltage changes. Thereby, power adjustment is performed.

[Sixth Solution Means] The plasma processing apparatus of the sixth solution means (as described in claim 6 at the beginning of the application) is the plasma processing apparatus of the third solution means, The power distribution state detecting means is a pickup coil wound around the high-frequency line, a high-voltage probe connected to the high-frequency line, a spectroscope installed toward the plasma space, and embedded or embedded in the vacuum chamber. It includes one or more of the attached thermocouples.

In the plasma processing apparatus according to the sixth aspect, when a locally high-concentration portion occurs in the plasma space, the change in the plasma state is based on the change in the plasma emission accompanying the change. It is detected by a spectroscope. Further, the change in the plasma state is directly detected by using a thermocouple based on the change in the plasma temperature distribution accompanying the change. Furthermore, since the change in the plasma state induces a change in the state of power distribution to each inductive coupling element due to the change in the degree of coupling between the plasma high concentration portion and the inductive coupling element,
Based on this, indirectly measuring the high-frequency line current to each inductive coupling element using a pickup coil or measuring the high-frequency line voltage to each inductive coupling element using a high-voltage probe is also possible. Can be detected.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Regarding the plasma processing apparatus of the present invention which has been achieved by the above-described solution, embodiments for carrying out the apparatus will be described in the following first and second embodiments and first and second embodiments.
A description will be given of a modified example. The first embodiment shown in FIGS. 1 and 2 embodies the above-described first, third, and fourth solving means, and the second embodiment shown in FIGS. The first, second, and third solving means embody the second solving means, and the first modification shown in FIG. 5 embodies the fifth solving means, and the second modification shown in FIG. The modification embodies the sixth solution means described above.

[0024]

First Embodiment A first embodiment of the plasma processing apparatus according to the present invention will be described with reference to the drawings. FIG. 1A is a schematic longitudinal sectional view of a main part thereof.
This corresponds to FIG. 9A of the related art. FIG. 1 (b)
FIG. 4 is a diagram of the inductive coupling element and the mutual interference reducing member as viewed obliquely.

This plasma processing apparatus (see FIG. 1 (a)) has a vacuum chamber body 2 and a vacuum chamber lid 3 (vacuum chamber) in which a plasma space 5 is formed, and a vacuum chamber attached thereto. Coils 21 and 2
4 (a plurality of inductive coupling elements), an RF power supply 12 for applying a high frequency to the plurality of inductive coupling elements, and a matching box 12a (power supply means). Also,
A cathode unit 4 installed in the plasma processing space 5, an RF power source 7 connected to the cathode unit 4, a vacuum pump 6 connected to the through-hole 2a of the vacuum chamber main body 2, and the like are also provided in a conventional manner.

On the other hand, the point that metal rings 31 to 34 (mutual interference reducing means) are provided between the coils 21 to 24 (see FIGS. 1A and 1B) and the RF power source 12
Power distribution control circuits 40 to 48 instead of the variable capacitors 13 for high-frequency lines from
(Refer to FIG. 1A) in that a power adjusting means is introduced (see FIG. 1A). The coils 21 to 24 are the same as the conventional ones in that they are divided into a plurality of pieces. However, in order to enable the insertion of the metal ring 31 and the like, the coils 21 to 24 have a shape and a size that can be arranged in order. It differs from the past in that it has a relationship.

In this plasma processing apparatus, when a rectangular workpiece 1 such as a liquid crystal substrate is processed, its main part is formed in a substantially rectangular shape. Here, a round workpiece such as a silicon wafer for IC is used. A case in which the object 1 is formed in a substantially round shape, a cylindrical shape, or an annular shape for processing will be described (FIG. 1B).
reference). The vacuum chamber main body 2 includes a plasma processing space 5.
Is formed from a metal such as aluminum so that the surroundings can be grounded. The vacuum chamber lid 3 efficiently transfers the alternating electromagnetic field sent from the coils 21 to 24 outside the chamber to the plasma processing space 5 inside the chamber. It is made of an insulating member such as ceramic having a high dielectric constant for good propagation.

The cathode portion 4 is formed by processing a good conductor such as a metal so as to also have the function of an electrode. Processing is also performed. As the vacuum pump 6, a rotary pump, a mechanical booster, or the like is used based on a required degree of vacuum. As the processing gas supplied to the plasma processing space 5 through the through-hole 2a of the vacuum chamber main body 2, a gas obtained by mixing an appropriate amount of a diluting gas with a reactive gas such as a CF-based gas or a silane gas is supplied. It has become so.

The RF power source 7 has a variable output power so as to adjust a bias voltage as a source of anisotropy in plasma processing, and has a frequency of 400 kHz to 20 MHz.
z is often used. The output power of the RF power supply 12 is also variable, and its maximum output power is large for exciting and maintaining the plasma. In addition, the frequency is often set to 5 MHz to 510 MHz.
The matching box 12a is provided along with the RF power supply 12 for reducing unnecessary reflected power, and the like.
This is also shown to clarify the high frequency line from the RF power supply 12 to the coils 21-24.

The coils 21 to 24 are circular coils of different diameters whose diameter increases in this order, and are arranged concentrically inside the coil unit 20 from the inner peripheral side to the outer peripheral side. Like the coil unit 10, the coil unit 20 is mounted on the vacuum chamber lid 3 from outside the chamber. Each of the metal rings 31 to 34 (see FIG. 1B) is made of a good conductor such as aluminum so that it can be grounded, and is formed in a cylindrical body or an annular body having different diameters but substantially equal heights. It is. Metal ring 31 is coil 2
1 and the diameter of the metal ring 32 is
1 and 22, the diameter of the metal ring 33 is set between the coils 22 and 23, and the diameter of the metal ring 34 is set between the coils 23 and 24.
At the time of attachment to the coil 0, the coils are alternately inserted between the coils 21 to 24.

The power distribution control circuits 40 to 48 (FIG. 1)
(A)), a current detection unit for detecting a distribution state of the power supplied to the plasma space 5 in order to perform appropriate adjustment by feedback control when adjusting the power distributed to each of the coils 21 to 24. 41 to 44 (power distribution state detecting means), a feedback control unit 40 (power distribution amount calculating means) for calculating a power distribution amount suitable for suppressing local fluctuation of plasma density based on the detected value, Wiring length variable sections 45 to 48 that vary the power to the coils 21 to 24 according to the calculated values, detect the state of distribution of the power supplied to the plasma space, and adjust the power based on the detection. It has become something.

The current detectors 41 to 44 will be described in detail in the section of a second modification later. The current detectors 41 to 44 are provided for each line from the RF power supply 12 to the coils 21 to 24 via the matching box 12a. In each case, the current of the corresponding line is detected and notified to the feedback control unit 40. The wiring length variable units 45 to 48 will be described in detail in the section of the first modified example later, but are provided for the installation lines of the current detection units 41 to 44, respectively, and all of them change the inductance of the corresponding line. With this, the current and voltage of the corresponding line can be varied. Note that the wiring length variable unit is for changing the power distribution ratio to each high-frequency line, so that the wiring length variable unit 48 for the line of the current detection unit 44 can be omitted.

The feedback control unit 40 is composed of an arithmetic circuit and a control circuit such as a microprocessor. In order to perform appropriate control of the multi-input system, an appropriate system control function such as a regulator or an observer based on a Wiener Hoff filter or a Kalman filter is performed. Or a plurality of single-input PID control means and the like, whereby the current detection values are continuously input from the current detection units 41 to 44, and based on the detection values. The power distribution state at that time is estimated, a deviation from an appropriate target power distribution amount for each of the coils 21 to 24 is calculated, and drive control of the wiring length variable units 45 to 48 is performed according to the calculated value. It has become. Note that the target power distribution amount is determined for each coil 2
It is preferable that a common initial value is determined so that the spatial density of power transmitted from 1 to 24 to the plasma processing space 5 is leveled, and fine adjustment is performed by actually measuring each device.

The usage and operation of the plasma processing apparatus of the first embodiment will be described with reference to the drawings. FIG. 2 schematically illustrates the operation state.
(A) and (c) show the distribution state of the electromagnetic field, and (b) and (d) show the distribution state of the plasma.

To perform the plasma processing on the object 1, first open a gate or the like (not shown), and then carry the object 1 into the vacuum chamber (2 + 3) and place it on the cathode unit 4. When the gate and the like are closed and the vacuum pump 6 is operated and gas supply and the like through the through-hole 2b are started appropriately, the atmosphere such as the gas pressure in the plasma processing space 5 is brought into a state where plasma can be generated. Become. The target power distribution amounts of the power distribution control circuits 40 to 48 will be described below while keeping the initial values.

Next, when the RF power source 12 is operated, a high frequency is applied to the coils 21 to 24 via the matching box 12a, and the coils 21 to 24 emit an alternating electromagnetic field. Also, at this stage, this field is
The light is propagated around the coils 21 to 24, and is particularly efficiently propagated to the plasma processing space 5 through the high-dielectric vacuum chamber lid 3. Since the magnetic field cannot propagate further in that direction, the electromagnetic field from each of the coils 21 to 24 is substantially restricted to the applicable range sandwiched by the metal rings 31 to 34 and the extended range thereof, and proceed. Thus, the equipotential lines 1 generated in the plasma processing space 5
4th mag can be said to be almost uniform when averaged as a whole,
A plurality of small blocks divided by the metal rings 31 to 34 become uneven (see FIG. 2A).

When the gas is excited in the plasma processing space 5 and the low-temperature plasma 15 is formed, the plasma acts on the surface of the workpiece 1 to perform the plasma processing. At this time, when the RF power source 7 is also operated, ions and the like in the low-temperature plasma 15 are accelerated toward the cathode unit 4, and anisotropy is added to the processing of the workpiece 1. In addition, the plasma high-concentration part 16 is generated one-to-one with respect to each of the coils 21 to 24 and becomes locally non-uniform.
Due to the strong diffusion capability, the distribution is leveled and substantially uniform on the substrate. On the other hand, the relative size of the plasma high-concentration portion 16 formed by each of the coils 21 to 24 varies depending on a change in gas flow rate and pressure during plasma processing, or a change in processing conditions due to a change in recipe, and furthermore, the deposition on the chamber wall. It constantly changes due to changes in plasma characteristics caused by changes in deposits and the like. This change degrades plasma uniformity on the substrate. Therefore, depending on the state of the plasma, it is inevitable that an abnormal plasma plasma high concentration portion 16a is generated (FIG. 2).
(B)).

When an abnormal plasma high concentration portion 16a appears, the amount of power distribution to the nearby coils, such as the coil 21, increases. Then, that is the fact that the current detectors 41 to 41
44 and the feedback control unit 40, and further, the feedback control unit 40 controls the wiring length variable units 45 to 48 so as to cancel the power fluctuation. Then, the equipotential lines 14 extending to the high plasma concentration portion 16a weaken and shrink, and the other equipotential lines 14 relatively intensify and protrude (see FIG. 2C). In this way, the power distribution to each of the coils 21 to 24 is adjusted. In this way, the abnormal high-concentration portion 16a is quickly extinguished even if it develops, or the development itself is suppressed, so that the low-temperature plasma 15 in the plasma processing space 5 is always maintained in a substantially uniform distribution state. (See FIG. 2D).

[0039]

Second Embodiment A specific configuration of a second embodiment of the plasma processing apparatus according to the present invention will be described with reference to the drawings. FIG. 3A is a schematic vertical cross-sectional view of a main part thereof.
This corresponds to FIG. 9A of the related art and FIG. 1A of the first embodiment. FIG. 3B is a view of the inductive coupling element as viewed obliquely.

This plasma processing apparatus is different from that of the first embodiment in that the vacuum chamber lid 3 which is a simple flat member is replaced by a plasma generation chamber 50 and an anode 51, The point is that the plasma generation spaces 52 to 54 are formed where the metal rings 32 to 34 exist (see FIG. 3). Also,
Along with this, the through-hole 2b is eliminated, and instead, the plasma gas is divided into a plasma generation gas and a processing gas, and the processing gas passes through the anode section 51 and the plasma generation gas passes through the plasma generation chamber section 50. This is also different in that it is fed into the vacuum chamber.

The anode portion 51 is formed of a metal plate that can be grounded, and is formed with a large number of communication ports 52a and 53a for communicating the plasma generation spaces 52 to 54 with the plasma processing space 5 and is perforated. A large number of processing gas supply ports 51a that open toward the plasma processing space 5 are also formed (see FIG. 3B). As the processing gas, a gas obtained by mixing an appropriate amount of a diluting gas with a reactive gas such as a CF-based gas or a silane gas is supplied.

The plasma generation chamber 50 is made of an insulating material such as ceramic. In this, a plurality (three in FIG. 3) of annular grooves serving as plasma generation spaces 52, 53, 54 are concentrically carved. It is formed. The plasma generation chamber 50 is fixedly mounted in a state where the opening sides (the lower surfaces in the longitudinal sectional views) of the plasma generation spaces 52 to 54 are in close contact with the upper surface of the anode unit 51. At that time, the plasma generation space 5
Openings 2 to 54 are communication ports 52 a and 53 of the anode section 51.
Positioning is performed so as to overlap with a and the like. Thereby, the plasma generation spaces 52 to 54 and the plasma processing space 5
Are adjacent to each other and communicate with each other, and the plasma generation spaces 52 to 54 extend linearly along the surface adjacent to the plasma processing space 5.

In the plasma generation chamber 50, the gas supply passages 52b and 53b for the plasma are also formed in a circular / line shape by a gas distribution member attached deeper (upper in the longitudinal sectional view) of the plasma generation spaces 52 to 54. Formed into a shape
Both are communicated by a large number of small holes, and the plasma generation spaces 52 to 54 receive the supply of the plasma generation gas from the bottom (the upper side in the longitudinal sectional view) to generate the high-density plasma 17 and open the communication ports 52a and 53a. It is sent to the plasma processing space 5 through the interface. An inert gas that does not react chemically, such as argon, is used as the plasma generating gas.

Further, in the plasma generation chamber 50, the back surface (the upper surface in the longitudinal sectional view) on the opening side of the plasma generation spaces 52 to 54 is cut off so as to leave the side walls and the bottom surrounding the plasma generation spaces 52 to 54. . Then, the coils 21 to 24 are packed therein (see FIG. 3B). Thereby, the plasma generation spaces 52 to 54 are extended portions of the plasma space 5 extending between the coils 21 to 24 (a plurality of inductive coupling elements).

At this time, permanent magnets 55 are also packed above and below the coils 21 to 24. These permanent magnets 5
Numeral 5 is packed into a space between the concentric annular plasma generating spaces 52 to 54 and also forms an annular shape, but is formed into small pieces in order to cut off an undesired induced current in the annular shape. A large number of permanent magnet pieces 55 are arranged along the side walls of the plasma generation spaces 52 to 54, so that the plasma generation spaces 52 to 5
4 is formed. Due to the presence of this magnetic circuit, electrons excited in the plasma generation spaces 52 to 54 repeatedly collide while staying therein,
The high-density plasma 17 is generated in the plasma generation spaces 52 to 54.

The usage and operation of the plasma processing apparatus according to the second embodiment will be described with reference to the drawings. FIG. 4 schematically shows the operation state.
(A) shows the distribution of the electromagnetic field, and (b) and (c) show the distribution of the plasma and the electromagnetic field.

When the RF power supply 12 is operated when the atmosphere in the plasma processing space 5 is in a state where plasma can be generated, alternating electromagnetic fields are generated from the coils 21 to 24 to which high frequency is applied. , Each coil 21 to
The electromagnetic field propagated around 24 is prevented from traveling in the vertical direction toward the plasma processing space 5 by the grounded anode unit 51, and instead, the plasma generation spaces 52 to 5
4 efficiently propagates in the horizontal direction. Until the plasma is excited and formed, the plasma generation chamber 5
The equipotential lines 14 and the like generated at 0 are superimposed on each other and distributed almost uniformly, and the plasma generation spaces 52 to 54
(See FIG. 4A).

When the alternating electromagnetic field reaches the plasma generation spaces 52 to 54, the gas for plasma generation therein is excited,
High-density plasma 17 is generated (see FIG. 4B). This high-density plasma 17 has a high ratio of ion species components,
The gas flows out of the plasma generation spaces 52 to 54 into the plasma processing space 5 through the communication ports 52a and 53a due to the expansion pressure or the like. Then, it is mixed with a processing gas or the like in the plasma processing space 5 and becomes low-temperature plasma 15.

When the high density plasma 17 is formed in the plasma generation spaces 52 to 54, the electromagnetic fields from the coils 21 to 24 are absorbed or reflected by the high density plasma 17, so that When it reaches 54, it cannot be further propagated in that direction, so that it is limited to a corresponding range partitioned by the plasma generation spaces 52 to 54 and separated from each other. In this way, the equipotential lines 14 and the like generated in the plasma processing space 5 can be said to be still substantially uniform when they are leveled as a whole, but the unevenness such as a plurality of small lumps divided by the plasma generation spaces 52 to 54 is arranged. (See FIG. 4B).

Then, the plasma 15 in the plasma processing space 5 acts on the surface of the workpiece 1 to perform a plasma processing according to a gas type and a plasma state. At this time, when the RF power source 7 is also operated, ions in the low-temperature plasma 15 are accelerated toward the cathode unit 4, and anisotropy is added to the processing of the workpiece 1. Since the plasma 15 has a high diffusion ability, the plasma 15 is quickly mixed and leveled in the plasma processing space 5 which does not reach the equipotential lines 14, and its density distribution becomes substantially uniform. However, as described above, depending on the plasma characteristics that change every moment during the plasma processing, each generation space 5
The high-density plasma 17 generated in 2 to 54 is likely to have a concentration difference, and it is unavoidable that the influence remains and the local high plasma concentration portion 16 is generated in the plasma processing space 5 (FIG. 4B). reference).

The density of the high-density plasma 17 in each of the plasma generation spaces 52 to 54 increases as the high-concentration plasma portion 16 appears.
When a concentration difference occurs in the coil, a coil close to it, for example, the coil 2
The power distribution amount such as 2 increases. Then, this is detected by the current detection units 41 to 44 and the feedback control unit 40, and further, the wiring length variable units 45 to 48 are controlled by the feedback control unit 40 so as to cancel the power fluctuation.
Then, the equipotential lines 14 extending to the plasma generation space 52 and the like close to the high plasma concentration portion 16 are weakened and shrunk, and the other equipotential lines 14 are relatively strengthened and protrude (FIG. 4).
(See (c)), power is distributed and supplied to each of the coils 21 to 24. In this way, the plasma high-concentration part 16 is quickly extinguished even if it is developed, or the development itself is suppressed, so that the low-temperature plasma 15 in the plasma processing space 5 is always kept in a substantially uniform distribution state. (See FIG. 4 (c)).

[0052]

First Modification Some more specific examples of the power varying means of the power adjusting means in the plasma processing apparatus of the present invention will be described. The wiring length variable section 45 shown in FIG.
Is used to change the power distributed to the coil 22. A spring portion 45a inserted in a high-frequency line from the matching box 12a to the coil 22 includes a spring portion 45a.
and a drive unit 45z that moves a pair of movable arms connected to both ends of the drive unit 45a. The drive unit 45z changes the distance between the movable arms according to the control of the feedback control unit 40, so that the inductance of the spring unit 45a is variable. It is supposed to be.

The wiring length changing section 45 shown in FIG.
Again, to vary the power allocated to the coil 22,
A good conductor rod 4 inserted in a high-frequency line from the matching box 12a to the coil 22 and having one end connected to one of the lines and the other end sliding with the other of the lines.
5b and a driving unit 45y for moving the rod 45b forward and backward, and the driving unit 45y changes the position of the rod 45b and changes the effective length of the rod 45b according to the control of the feedback control unit 40, so that the inductance in the high-frequency line is changed. Is made variable.

The wiring length variable section 45 shown in FIG.
A wiring bobbin 45w inserted in a high-frequency line from the matching box 12a to the coil 22 and a drive unit 45x for rotating the wiring bobbin 45w while ensuring contact pressure between the wiring bobbin 45w and the high-frequency line are provided. The drive unit 45x changes the winding amount of the wiring bobbin 45w according to the control of the control unit 40 and changes the length of the line portion 45c drawn out from the drive unit 45x, so that the inductance in the high-frequency line is variable.

The wiring length variable section 45 shown in FIG.
It has a main wiring part 45d inserted in a high-frequency line from the matching box 12a to the coil 22, and a bidirectional rotatable driving part 45v having a rotating shaft connected to the center end of the main wiring part 45d. , Feedback control unit 40
Is driven by the mainspring-like wiring part 45d
, The inductance of the high-frequency line can be varied.

The wiring length variable section 45 shown in FIG.
A magnet 45u such as an electromagnet or a permanent magnet that extends a magnetic flux line from the matching box 12a to the high-frequency line 45c extending from the matching box 12a to the coil 22 is reciprocated under the control of the feedback control unit 40, thereby changing the magnetic field intensity around the line 45c. And line 45c in the high-frequency line
The inductance of the portion is made variable.

The wiring length variable section 45 shown in FIG.
A plurality of branch lines 45f of different lengths inserted in a high-frequency line from the matching box 12a to the coil 22
And a switch 45t that is switched so that any one of the branch lines 45f is connected to the high-frequency line.
By changing the connection destination of the switch 45t according to the control of the feedback control unit 40 and changing the wiring length at the branch line 45f, the inductance of the high-frequency line can be varied.

The wiring length variable section 45 shown in FIG.
A bridge 45s of a good conductor which is inserted into the cut portion 45g of the high-frequency line from the matching box 12a to the coil 22 and has one end sliding on one side of the line cut portion 45g and the other end sliding on the other of the line cut portion 45g. In addition, the effective length and inductance of the high-frequency line are variable by keeping the cut portion 45g of the high-frequency line substantially parallel and moving the bridge 45s back and forth along the cut portion 45g under the control of the feedback control section 40 in this state. It is supposed to be.

[0059]

[Second Modification] A more specific configuration example of the current detecting means of the power adjusting means in the plasma processing apparatus of the present invention will be described. The current detection unit 42 shown in FIG. 6 is a power distribution state detection unit that detects the distribution state of the power supplied to the plasma space (5, 52 to 54).
2 is provided for the high-frequency line to 2.

The current detection section 42 cuts a high-frequency line formed of a copper foil or the like in a strip shape and connecting the matching box 12a and the variable wiring length section 45, and inserts a core wire 42a made of a copper wire or the like into the high-frequency line. By connecting, it is inserted into the high-frequency line. The core wire 42a is covered with an insulating coating 42b. Upon insertion, a pickup coil 42c obtained by further rounding the coil into an annular shape is connected to the core wire 42a and the insulating coating 42b.
It is attached so as to surround b. Pickup coil 4
2c is a high voltage probe 42d having a large input resistance.
The output of the high-voltage probe 42d is sent to an appropriate monitoring oscilloscope 42e or feedback control unit 40.

As a result, the coil 22
The current distributed to the high-frequency line leading to is detected. The same applies to other high-frequency lines. Although illustration is omitted, by connecting a probe similar to the high-voltage probe 42d to the core wire 42a or the high-frequency lines before and after the core wire 42a,
A high-frequency voltage waveform distributed to the line is detected. Then, the phase difference between the current waveform and the voltage waveform is determined. Thereby, the power distributed to each of the coils 21 to 24 can be accurately detected.

[0062]

FIG. 7 shows a workpiece 1 having a diameter of 300 mm.
It is a graph showing the measurement results of the device for the target, in order to compare the distribution state of the ion current, the horizontal axis is taken from the center point, and the vertical axis is taken as the standard value of the ion current Things. The ion current was measured by inserting a probe into the plasma processing space 5, and normalized so that the maximum value was "1". The output power of the RF power supply 12 at the time of measurement was 2250 W, the flow rate of argon used for the plasma generation gas was 400 sccm, and the gas pressure was 30 mTorr. 1 Torr is about 1
33 Pascal, 1 sccm is about 1.67 × 10 ^-8
Cubic meters per second (gas: standard state). Compared to the case where the electromagnetic field distribution is made uniform (see the broken line graph),
By adjusting the power distribution, the uniformity in the distribution state of the ion current is much improved (see the solid line graph).

FIG. 8 is a distribution diagram of the etching rate, which was measured in order to confirm the influence of a change in gas pressure on the uniformity of the etching rate. The horizontal axis indicates the distance from the center point, and the vertical axis indicates the etching rate in each part of the workpiece 1. The unit of the horizontal axis is mm, and the unit of the vertical axis is Angstroms / minute. The output power of the RF power supply 12 at the time of measurement is 225
0 W, the flow rate of argon used for the plasma generation gas was 400 sccm, and the flow rate of carbon fluoride used for the processing gas was 20 sccm. Gas pressure is 30mT
The etching rate distribution when the gas pressure is 50 mTorr (graph A), the etching rate distribution when the gas pressure is 50 mTorr (graph B), and the etching rate distribution when the gas pressure is 80 mTorr (graph C) show good uniformity. It has become something.

[0064]

As is apparent from the above description, in the plasma processing apparatus according to the first aspect of the present invention, the independence is improved by reducing the mutual interference of a plurality of inductive coupling elements. Since the local controllability of the electromagnetic field distribution is improved and the plasma density distribution in the plasma space becomes uniform, there is an advantageous effect that a plasma processing apparatus with good uniformity can be realized.

Further, in the plasma processing apparatus according to the second solution of the present invention, the power applied to the inductive coupling element is supplied to the plasma without being wasted by the mutual interference reducing means. In addition, there is an advantageous effect that a plasma processing apparatus having good energy efficiency in addition to uniformity can be realized.

Further, in the plasma processing apparatus according to the third and fourth solutions of the present invention, the power to each inductive coupling element is subjected to feedback control to offset the local fluctuation of the plasma density. The advantage is that a plasma processing apparatus with good uniformity can always be realized by reducing the temperature.

Further, in the plasma processing apparatus according to the fifth solution of the present invention, the power to each inductive coupling element can be adjusted without using a variable capacitor.

In the plasma processing apparatus according to the sixth aspect of the present invention, a change in the plasma state can be detected directly or indirectly.

[Brief description of the drawings]

FIG. 1 is a schematic view of a longitudinal section of a main part of a first embodiment of a plasma processing apparatus of the present invention.

FIG. 2 is an explanatory diagram of the operation state.

FIG. 3 is a schematic diagram of a longitudinal section of a main part of a second embodiment of the plasma processing apparatus of the present invention.

FIG. 4 is an explanatory diagram of the operation state.

FIG. 5 is a specific modified example of the power variable means.

FIG. 6 is a specific example of a current detection unit.

FIG. 7 is a distribution diagram of an ion current.

FIG. 8 is a distribution diagram of an etching rate.

FIG. 9 is a schematic longitudinal sectional view and an operation state explanatory view of a conventional device.

[Explanation of symbols]

Reference Signs List 1 workpiece (plasma processing target) 2 vacuum chamber body (vacuum chamber) 2a through-hole (processing gas supply port) 2b through-hole (exhaust suction port) 3 vacuum chamber lid (vacuum chamber) 4 cathode (mounting) 4a support 5 plasma processing space (plasma space) 6 vacuum pump 7 RF power supply (high frequency power supply) 7a blocking capacitor 10 coil unit (antenna unit) 11 coil (antenna) Reference Signs List 12 RF power supply (high-frequency power supply, power supply means) 12a Matching box (power supply means) 13 Variable capacitor (current adjustment means) 14 Equipotential line 15 Low temperature plasma 16 Plasma high concentration part 17 High density plasma 20 Coil unit (antenna unit) 21, 22, 23, 24 Coil (antenna, induction Conductive coupling elements) 31, 32, 33, 34 Metal ring (ground conductor, mutual interference reduction means) 40 Feedback control unit (distribution amount calculation means, power adjustment means) 41, 42, 43, 44 Current detection unit (power distribution state) Detection, power adjustment means) 45, 46, 47, 48 Wiring length variable part (power variable means, power adjustment means) 50 Plasma generation chamber part (vacuum chamber) 51 Anode part (counter electrode) 51a Processing gas supply port 52, 53 , 54 Plasma generation space (expansion of plasma space, reduction of mutual interference) 52a, 53a Communication port (communication passage) 52b, 53b Gas supply path for plasma 55 Permanent magnet (magnetic member of magnetic circuit for plasma confinement)

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/31 H01L 21/302 B (72) Inventor Tetsuo Tokumura 1-5-Takazukadai, Nishi-ku, Kobe-shi, Hyogo Prefecture 5 Kobe Steel, Ltd.Kobe Research Institute (72) Inventor Jun Munemasa 2-3-1 Araimachi Shinhama, Takasago City, Hyogo Prefecture Kobe Steel, Ltd.Takasago Works, Ltd. (72) Inventor Kiyotaka Ishibashi Kobe, Hyogo Prefecture 1-5-5 Takatsukadai, Nishi-ku, Kobe Kobe Steel, Ltd.Kobe Research Institute (72) Inventor Toshiki Segawa 1-5-5, Takatsukadai, Nishi-ku, Kobe, Hyogo Prefecture Kobe Steel, Ltd.Kobe Research Institute Institution (72) Inventor Toshihisa Nozawa 1-5-5 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo F-term in Kobe Steel, Ltd.Kobe Research Institute 4K030 AA06 FA04 HA06 HA16 KA30 KA39 KA41 KA45 LA15 LA18 5F004 AA01 BA20 BB07 BB13 BB18 BD01 BD03 BD04 DA01 DA02 DA03 DA23 DB01 DB03 5F045 AA08 AF01 AF07 BB01 DP04 EH04 EH11 EH16 GB08

Claims (6)

[Claims] 1. A plasma processing apparatus comprising: a vacuum chamber in which a plasma space is formed; a plurality of inductive coupling elements provided in the vacuum chamber; and power supply means for applying a high frequency to the plurality of inductive coupling elements. A power adjusting means provided for the high-frequency line and adjusting power distributed to the plurality of inductive coupling elements; and a mutual interference reducing means provided or formed between the plurality of inductive coupling elements. A plasma processing apparatus comprising: 2. The plasma processing apparatus according to claim 1, wherein said mutual interference reducing means is an extension of said plasma space extending between said plurality of inductive coupling elements. 3. The plasma processing apparatus according to claim 1, further comprising a power distribution state detecting means for detecting a distribution state of the electric power supplied to the plasma space. 4. The plasma processing apparatus according to claim 3, wherein said power adjusting means adjusts the power based on the detection of said power distribution state detecting means. 5. The plasma processing apparatus according to claim 1, wherein said power adjusting means changes the inductance of said high-frequency line. 6. The power distribution state detecting means includes a pickup coil wound on the high frequency line, a high voltage probe connected to the high frequency line, a spectroscope installed toward the plasma space, and 4. The plasma processing apparatus according to claim 3, wherein the plasma processing apparatus includes one or a plurality of thermocouples embedded or attached to the vacuum chamber.