JP4887202B2 - Plasma processing apparatus and high-frequency current short circuit - Google Patents

Description

  The present invention relates to a plasma processing apparatus and a high-frequency current short circuit, and more particularly to a plasma processing apparatus for performing plasma processing on a substrate.

  As shown in FIG. 6, a plasma processing apparatus 50 that performs an etching process on a glass substrate for a seventh-generation or eighth-generation liquid crystal panel includes a chamber 51 that houses a glass substrate (hereinafter simply referred to as “substrate”) G. And a lower electrode 52 on which the substrate G is placed, and an upper electrode 54 of the shower head 53 facing the lower electrode 52. In this plasma processing apparatus 50, a processing gas supplied to a space between the upper electrode 54 and the lower electrode 52 (hereinafter referred to as “processing space”) is excited by a high-frequency electric field to generate plasma, and the plasma generates a substrate. G is etched.

  In the plasma processing apparatus 50, the lower electrode 52 is supported by a ground substrate 55, and the ground substrate 55 is connected to the chamber 51 via a pillar 56 and a bellows 57 that are movable in the vertical direction. Since the chamber 51 is grounded, a high-frequency current flows through the path of the upper electrode 54 → the plasma in the processing space → the lower electrode 52 → the ground substrate 55 → the pillar 56 → the bellows 57 → the chamber 51 during the etching process. Here, since the pillar 56 and the bellows 57 are made of a conductor, the ground substrate 55 has the same potential as the chamber 51 in terms of direct current. .

  Further, since the 7th generation and 8th generation liquid crystal panels are very large, the lower electrode 52 and the ground substrate 55 are also very large. As a result, the space between the ground substrate 55 and the wall surface of the chamber 51 (hereinafter referred to as “lower portion”). The space is also very large. Since a potential difference is generated between the ground substrate 55 and the wall surface of the chamber 51 that do not have the same potential in terms of alternating current, a high-frequency current may flow in the lower space to generate capacitively coupled plasma or abnormal discharge. This plasma reduces the density of the plasma in the processing space and deteriorates the uniformity. In addition, power efficiency is reduced due to abnormal discharge, and the ground substrate 55 is scraped to generate particles.

Therefore, the plasma processing apparatus 50 is provided with a thin plate-like short-circuit plate 58 made of a conductive material that short-circuits the ground substrate 55 and the wall surface of the chamber 51 in an alternating manner (see, for example, Patent Document 1).
Japanese Patent No. 3710081

  However, in order to perform the etching process on the substrate G for the 7th generation or 8th generation liquid crystal panels, it is necessary to supply high power, for example, high frequency power of 10 kW or more to the processing space. At this time, the high-frequency current flowing through the processing space and the ground substrate 55 is 100 A or more. Further, the short-circuit plate 58 has a self-inductance, and inductive reactance (impedance) is generated corresponding to the high-frequency current. As a result, the potential of the ground substrate 55 exhibits a high frequency voltage of several hundred volts.

  In order to lower the potential of the ground substrate 55, it is most effective to increase the number of short-circuit plates 58, but since components such as a lifter pin holder (not shown) are arranged in the lower space, It is difficult to increase the number of short-circuit plates 58 because there is no space.

  Therefore, the potential difference between the ground substrate 55 and the wall surface of the chamber 51 is still not eliminated, and capacitive coupling plasma and abnormal discharge may occur in the lower space due to the potential difference.

  An object of the present invention is to provide a plasma processing apparatus and a high-frequency current short circuit capable of reducing a potential difference between a ground substrate supporting at least one of a lower electrode and an upper electrode and an inner wall of a container.

In order to achieve the above object, a plasma processing apparatus according to claim 1 includes a storage container that stores a substrate, a lower electrode that is disposed in the storage container and mounts the substrate, and the lower part An upper electrode disposed opposite to the electrode and supplying a processing gas into the container; a high-frequency power source connected to at least one of the lower electrode or the upper electrode; and at least one of the lower electrode or the upper electrode In the plasma processing apparatus, comprising: a grounding substrate that is supported via an insulating portion and spaced apart from the inner wall of the housing container; and a shorting plate that short-circuits the grounding substrate and the inner wall of the housing container. and a capacitor is interposed between the inner wall of the container, the capacitor is provided on an inner wall of the container, the short-circuiting plate in cross-section consists of a rectangular straight conductors, small in the middle Both features that you have branched into two.

If the claims 2 plasma processing apparatus, wherein in the plasma processing apparatus according to claim 1, in which the capacitive reactance of the capacitor and X _C, the inductive reactance of the short-circuiting plate was X _L, X C ₌ -X It is characterized in that _L / 2 is established.

  The plasma processing apparatus according to claim 3 is the plasma processing apparatus according to claim 1 or 2, wherein the capacitor includes an insulating layer and two conductors sandwiching the insulating layer, and the insulating layer is a ceramic sheet. And one selected from the group consisting of a thermal sprayed ceramic layer and a fluororesin layer.

The plasma processing apparatus according to claim 4 is the plasma processing apparatus according to claim 1, wherein another capacitor is interposed between the short-circuit plate and the ground substrate, and the other capacitor is provided on the ground substrate. The capacitance of the capacitor is C1, the self-inductance of the short-circuit plate is L, the capacitance of the other capacitor is C2, the frequency of the high-frequency power supplied from the high-frequency power source is f, and the angular frequency ω is 2πf. In this case, C1 = C2 = 2 / (ω ² × L) is established.

In order to achieve the above object, a high-frequency current short-circuit circuit according to claim 5, a storage container for storing a substrate, a lower electrode as a mounting table disposed in the storage container and mounting the substrate, An upper electrode disposed opposite to the lower electrode and supplying a processing gas into the container; a high-frequency power source connected to at least one of the lower electrode or the upper electrode; and the lower electrode or the upper electrode A high-frequency current short circuit for short-circuiting the grounding substrate and the inner wall of the housing container in a plasma processing apparatus comprising: a grounding substrate disposed at a distance from the inner wall of the housing container while supporting at least one through an insulating portion A short-circuit plate that short-circuits the inner wall of the grounding substrate and the storage container, and a capacitor interposed between the short-circuit plate and the inner wall of the storage container. Provided on an inner wall of the container, the short-circuiting plate in cross-section consists of a rectangular straight conductors, characterized that you have branched into at least two in the middle.

According to the plasma processing apparatus of claim 1 and the short-circuit of the high-frequency current of claim 5 , since the capacitor is interposed between the grounding substrate and the short-circuit plate that short-circuits the inner wall of the container, and the inner wall of the container, The potential difference between the ground substrate and the inner wall of the container can be shared by the short-circuit plate and the capacitor. Further, since the capacitor is provided on the inner wall of the container, the potential difference between the ground substrate and the inner wall of the container is substantially the potential difference between the ground substrate and the capacitor, and the potential difference is a potential difference shared by the short-circuit plate. There is nothing else. The short-circuit plate is made of a straight conductor having a rectangular cross section, and is branched into at least two parts along the way. When the short-circuit plate is branched, the cross-sectional area of each branch path decreases, but the number of high-frequency current paths can be increased. As a result, the inductance of the entire short-circuit plate can be reduced. As a result, the potential of the ground substrate can be lowered. As a result, the potential difference between the ground substrate that supports at least one of the lower electrode and the upper electrode and the inner wall of the container can be reduced .

According to the plasma processing apparatus of the second aspect, the capacitive reactance X _C of the capacitor and the inductive reactance X _L of the short-circuit plate satisfy X _C = −X _L / 2. Assuming that the high-frequency current is I, the potential V ₁ of the ground substrate when no capacitor is interposed between the short-circuit plate and the inner wall of the storage container is represented by V ₁ ≈X _L × I. The potential V ₂ of the ground substrate when a capacitor is interposed between the inner walls is represented by V ₂ ≈ (X _L + X _C ) × I. Here, since X _C = −X _L / 2 holds, V ₂ ≈½ × X _L × I. That is, the V ₂ can be 1/2 of V _1, it is possible to short-circuit plate is reliably reduced potential to share. At this time, since the potential difference capacitor share also becomes half of V _1, both between the ground substrate and the capacitor, and a potential difference between the inner wall of the condenser and container can be suitably reduced, Accordingly, it is possible to suppress the generation of capacitively coupled plasma and abnormal discharge between the ground substrate and the capacitor or between the capacitor and the inner wall of the container.

According to the plasma processing apparatus of claim 4, another capacitor is interposed between the short-circuit plate and the ground substrate, and the other capacitor is provided on the ground substrate, and the capacitance C1 of the capacitor and the self-inductance of the short-circuit plate. L, the capacitance C2 of the other capacitor, and the angular frequency ω (= 2πf) where f is the frequency of the high-frequency power satisfy C1 = C2 = 2 / (ω ² × L). Assuming that the high-frequency current is I, the potential V ₃ of the ground substrate when a capacitor is interposed between the short-circuit plate and the inner wall of the container and another capacitor is interposed between the short-circuit plate and the ground substrate is the capacitive reactance and _{X C1,} the capacitive reactance of the other capacitor and _{X C2,} the inductive reactance of the short-circuiting plate to _{X L,} indicated by _{V 3 ≒ (X C1 + X} L + X C2) × I, further When developed, the potential V ₃ is represented by V ₃ ≈ (−1 / (ω × C1) + ω × L−1 / (ω × C2)). Here, since C1 = C2 = 2 / (ω ² × L) holds, V ₃ ≈0. That is, since the potential of the ground substrate can be set to 0, it is possible to prevent the occurrence of capacitively coupled plasma and abnormal discharge in the vicinity of the ground substrate.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  First, the plasma processing apparatus according to the first embodiment of the present invention will be described.

  FIG. 1 is a cross-sectional view schematically showing a configuration of a plasma processing apparatus according to the present embodiment. This plasma processing apparatus is configured to perform an etching process on a glass substrate for a liquid crystal display (LCD).

  In FIG. 1, the plasma processing apparatus 10 includes a rectangular tube-shaped chamber 11 (accommodating container) that accommodates a rectangular glass substrate (hereinafter simply referred to as “substrate”) G having a side of about 1 m, for example. The chamber 11 is made of aluminum, and most of the inner wall of the chamber 11 is covered with alumite.

  A shower head 12 (upper electrode) is disposed on the ceiling portion of the chamber 11. The shower head 12 has an upper electrode plate 13 that is a rectangular conductive plate and a conductive member that supports the upper electrode plate 13 in a detachable manner. And an upper electrode base 14 made of a body. A buffer chamber 15 is provided inside the upper electrode base 14, and a processing gas introduction pipe 16 is connected to the buffer chamber 15. The upper electrode plate 13 has a large number of gas holes 17 communicating with the buffer chamber 15 and the chamber 11. The processing gas introduction pipe 16 is connected to a processing gas supply apparatus (not shown), and the processing gas supply apparatus introduces the processing gas into the buffer chamber 15 through the processing gas introduction pipe 16. The shower head 12 supplies the processing gas introduced into the buffer chamber 15 to the space between the upper electrode plate 13 and the lower electrode plate 23 described later (hereinafter referred to as “processing space S”) through the gas hole 17. . Here, since the shower head 12 is supported from the ceiling portion of the chamber 11 via the upper insulating portion 22, the shower head 12 is sufficiently electrically floating from the chamber 11.

  The upper electrode plate 13 is connected to the high-frequency power source 20 through the upper electrode base portion 14, the matching circuit 18 and the conductive path 19. A matching box 21 is provided on the ceiling of the chamber 11 so as to include the matching circuit 18. Since the matching box 21 is grounded, it functions as a grounding housing for the matching circuit 18. The high frequency power supply 20 supplies a predetermined high frequency power, for example, a high frequency power of 13.56 MHz to the upper electrode plate 13. The upper electrode plate 13 applies a high frequency voltage to the processing space S to generate a high frequency electric field. The high frequency electric field excites the processing gas supplied to the processing space S to generate plasma. As the processing gas, for example, a gas containing halogen, specifically, a gas composed of a halogen compound, oxygen gas, argon gas, or the like is used.

  A rectangular lower electrode plate 23 also serving as a mounting table on which the substrate G is mounted is disposed at the bottom of the chamber 11. The lower electrode plate 23 faces the upper electrode plate 13 and is supported by a ground substrate 26 made of aluminum via a lower insulating portion 25. The ground substrate 26 is disposed away from the bottom of the chamber 11 and is supported by a cylindrical pillar 27. The pillar 27 is disposed on a support plate 28 that moves in the vertical direction (in the direction of the arrow in the figure) by a drive mechanism (not shown). Therefore, as the support plate 28 moves up and down, the ground substrate 26 and the lower electrode plate 23 also move up and down. The support plate 28 is connected to the bottom of the chamber 11 via a bellows 29, and the bellows 29 partitions the inside of the chamber 11 and the outside of the chamber 11 in an airtight manner. The pillar 27, the support plate 28, and the bellows 29 are all made of a conductor.

  A chiller channel (not shown) is provided in the lower electrode plate 23, and the substrate G placed on the lower electrode plate 23 is cooled by the refrigerant flowing through the chiller channel. The lower insulating portion 25 is made of a dielectric material or an atmospheric layer, and causes the lower electrode plate 23 to be sufficiently electrically floated from the ground substrate 26 and then from the chamber 11.

  One end of a conductive path 30 provided in the pillar 27 is connected to the lower electrode plate 23, and an impedance adjusting unit 31 is interposed in the conductive path 30. The other end of the conductive path 30 is connected to the bottom of the chamber 11 through a support plate 28 and a bellows 29. In the present embodiment, the upper electrode plate 13 and the lower electrode plate 23 correspond to a cathode electrode and an anode electrode, respectively.

  An exhaust passage 32 is connected to the bottom of the chamber 11, and an exhaust device (not shown) such as a turbo molecular pump or a dry pump is connected to the exhaust passage 32. The exhaust device exhausts the inside of the chamber 11 through the exhaust path 32. Furthermore, a gate valve 34 for opening and closing the transfer port 33 for the substrate G is provided on the side wall of the chamber 11.

  In the plasma processing apparatus 10, a high frequency current flows through a high frequency power source 20 → a matching circuit 18 → a shower head 12 → a plasma in the processing space S → a lower electrode plate 23 → an impedance adjusting unit 31 → a chamber 11 → a matching box 21 → a ground path. Since the high-frequency current may flow in a short circuit from the shower head 12 to the wall portion of the chamber 11 via plasma, the impedance of the path (return path) from the lower electrode plate 23 to the matching box 21 is changed to the impedance adjusting section. The high frequency current is prevented from flowing in a short-circuit manner on the wall portion of the chamber 11 by adjusting by 31.

  Further, in the plasma processing apparatus 10, high-frequency electric power is generated in the processing space S to generate a high-frequency electric field, thereby exciting the processing gas supplied from the shower head 12 in the processing space S and generating high-density plasma. The substrate G is etched by the plasma.

  The operation of each component of the plasma processing apparatus 10 is controlled by a CPU of a control unit (not shown) provided in the plasma processing apparatus 10 according to a program corresponding to the etching process.

  Further, the plasma processing apparatus 10 includes a short-circuit plate 36 that short-circuits the ground substrate 26 and the inner wall of the chamber 11, and a capacitor 37 interposed between the short-circuit plate 36 and the inner wall of the chamber 11. The short-circuit plate 36 is a thin plate-like conductor having a rectangular cross section made of a conductive material such as metal, for example, stainless steel or Hastelloy (registered trademark).

  One end of the short-circuit plate 36 is connected to the lower surface of the ground substrate 26 via a connection portion 38, and the other end of the short-circuit plate 36 is connected to an inner wall of the chamber 11, specifically, a capacitor 37 provided on the bottom portion of the chamber 11. ing.

  The capacitor 37 is composed of an insulating layer 37a and two metal plates 37b and 37c such as an aluminum plate that sandwich the insulating layer 37a, and a portion that may come into contact with plasma is covered with an insulating film such as alumite. Has been. The insulating layer 37a is made of, for example, a ceramic sheet, a sprayed ceramic layer, or a fluororesin layer (Teflon (registered trademark) layer). As the capacitor 37, a commercially available vacuum capacitor or variable capacitor having plasma resistance can be used in addition to the above-described specification.

  In the plasma processing apparatus 10, the short-circuit plate 36 and the capacitor 37 constitute a short circuit that short-circuits between the ground substrate 26 and the inner wall of the chamber 11.

  In the plasma processing apparatus 10, when a high-frequency current flows between the ground substrate 26 and the inner wall of the chamber 11, the short-circuit plate 36 has a self-inductance, so that an inductive reactance is generated in the short-circuit plate 36. Since the capacitor 37 has a capacitance, a capacitive reactance is generated in the capacitor 37. In the plasma processing apparatus 10, the capacitor 37 is interposed between the short-circuit plate 36 and the inner wall of the chamber 11, so that the short-circuit plate 36 and the capacitor 37 constitute a series circuit between the ground substrate 26 and the inner wall of the chamber 11. . Therefore, the short-circuit plate 36 and the capacitor 37 can share a potential difference generated when a high-frequency current flows between the ground substrate 26 and the inner wall of the chamber 11.

Here, the potential V ₂ of the ground substrate 26 is set such that the inner wall of the chamber 11 is a ground potential, the impedance of the short-circuit plate 36 is Z _L , the impedance of the capacitor 37 is Z _C, and between the ground substrate 26 and the inner wall of the chamber 11. Assuming that the high-frequency current flowing through is I, the following equation (1) is obtained.
V ₂ = (Z _L + Z _C ) × I (1)
Normally, Z _L and Z _C are represented by R + jX (X is reactance), but in the plasma processing apparatus 10, R is very small compared to X and can be ignored. Thus, in this embodiment, the inductive reactance of the short-circuiting plate 36 and X _L, the capacitive reactance of the capacitor 37 and X _C, the potential V ₂ of the ground substrate 26 is represented by the following formula (2).
V ₂ ≈ ( _XL + X _C ) × I (2)
In the present embodiment, the potential V ₂ is reduced by adjusting the capacitance of the capacitor 37. Specifically, the capacitance of the capacitor 37 is adjusted so that the following formula (3) is satisfied.
X _C = −X _L / 2 (3)
As a result, the potential _{V 2} of the ground substrate 26 is represented by the following formula (4).
V ₂ ≒ 1/2 × _XL × I (4)
On the other hand, when the ground substrate and the inner wall of the chamber are short-circuited only by the short-circuit plate as in the conventional plasma processing apparatus, the potential V _{1 of the} ground substrate is expressed by the following formula (5).
V ₁ ≈ _XL × I (5)
Comparing the expressions (4) and (5), the potential _{V 2} of the ground substrate 26 is 1/2 of the potential _{V 1} of the ground substrate in a conventional plasma processing apparatus. Therefore, by interposing the capacitor 37 between the short-circuit plate 36 and the inner wall of the chamber 11 and adjusting the capacitance of the capacitor 37 so that the above equation (3) is satisfied, the potential V ₂ of the ground substrate 26 is conventionally increased. it can be 1/2 of the potential V ₁ of the ground substrate in the plasma processing apparatus.

At this time, the potential V _{C of the} capacitor 37 is expressed by the following formula (6).
V _C ≈ X _C × I (6)
Here, from the above equation (3), the potential V _{C of the} capacitor 37 is expressed by the following equation (7).
V _C ≈−1 / 2 × _XL × I (7)
Therefore, the potential V _{C of the} capacitor 37 can also be ½ of the potential V ₁ of the ground substrate in the conventional plasma processing apparatus. That is, the potential difference shared by the capacitor 37 is also ½ of V ₁ .

  According to the plasma processing apparatus 10 according to the present embodiment, the short-circuit plate 36 and the capacitor 37 can share a potential difference generated when a high-frequency current flows between the ground substrate 26 and the inner wall of the chamber 11. Further, since the capacitor 37 is provided on the inner wall of the chamber 11, the potential difference between the ground substrate 26 and the inner wall of the chamber 11 is substantially a potential difference between the ground substrate 26 and the capacitor 37, and the potential difference is the short-circuit plate 36. Is nothing but the potential difference shared by Therefore, the potential difference between the ground substrate 26 that supports the lower electrode plate 23 and the inner wall of the chamber 11 can be reduced.

In the plasma processing apparatus 10 described above, X _C = −X _L / 2 (the above formula (3)) is established by adjusting the capacitance of the capacitor 37, so that the potential V ₂ of the ground substrate 26 is V ₂ ≈ 1/2 × X _L × I (the above formula (4)). On the other hand, the potential V ₁ of the ground substrate of the conventional plasma processing apparatus is expressed by V ₁ ≈X _L × I (the above formula (5)). That is, the V ₂ can be 1/2 of V _1, may be short-circuiting plate 36 is reliably reduced potential to share.

Further, since the potential difference shared by the capacitor 37 is also ½ of V ₁ , the potential difference between the ground substrate 26 and the capacitor 37 and between the capacitor 37 and the inner wall of the chamber 11 can be appropriately reduced. Accordingly, it is possible to suppress the generation of capacitively coupled plasma and abnormal discharge between the ground substrate 26 and the capacitor 37 and between the capacitor 37 and the inner wall of the chamber 11.

In the plasma processing apparatus 10 described above, the potential V ₂ of the ground substrate 26 is set to ½ of the potential V ₁ of the ground substrate in the conventional plasma processing apparatus by adjusting the capacitance of the capacitor 37. change the potential difference is short-circuiting plate 36 is shared by adjusting the electrostatic capacitance may be substantially zero potential V ₂ of the ground substrate 26.

  Next, a plasma processing apparatus according to the second embodiment of the present invention will be described.

  The present embodiment is basically the same in configuration and operation as the first embodiment described above, and is different only in the configuration of the short circuit that short-circuits the ground substrate 26 and the wall surface of the chamber 11. The description of the configuration and operation will be omitted, and different configurations and operations will be described below.

  FIG. 2 is a cross-sectional view schematically showing the configuration of the plasma processing apparatus according to the present embodiment.

  In FIG. 2, the plasma processing apparatus 40 includes a short-circuit plate 41 that short-circuits the ground substrate 26 and the inner wall of the chamber 11. The short-circuit plate 41 is also a thin plate-like conductor having a rectangular cross section made of a conductive material such as metal, for example, stainless steel or Hastelloy (registered trademark).

  One end of the short-circuit plate 41 is connected to the ground substrate 26 via the connection portion 38, and the other end of the short-circuit plate 41 is connected to the inner wall of the chamber 11 via the connection portion 42. In the plasma processing apparatus 40, the short-circuit plate 41 constitutes a short circuit that short-circuits between the ground substrate 26 and the inner wall of the chamber 11.

  3 is a front view showing the short-circuit plate in FIG. 2, FIG. 3 (A) shows a case where the short-circuit plate is branched into two, and FIG. 3 (B) shows a case where the short-circuit plate is branched into three. Show.

In general, the inductance L of a straight conductor having a rectangular cross section made of metal is expressed by the following formula (8), where a (cm) is a length of the straight conductor, b (cm) is a width, and c (cm) is a thickness. Indicated.
L = 0.002a × [2.3303 × log {2a / (b + c)} + 0.5 + 0.2235 × (b + c) / a] (8)
Here, if b >> c, the above equation (8) is expressed by the following equation (8) ′.
L≈0.002a × {2.3303 × log (2a / b) + 0.5 + 0.2235 × b / a} (8) ′
At this time, if the value of L in the above formula (8) ′ is A and the width-length ratio of the linear conductor is b / a, the relationship between A and b / a is as shown in FIG. In FIG. 4, the horizontal axis indicates the width-length ratio b / a, and the vertical axis indicates each width-length ratio b where A is 1 when the width-length ratio b / a is 0.5. A standardized A when A corresponding to / a is standardized is shown.

  From the relationship shown in FIG. 4, even if the width-length ratio b / a is halved from 0.5 to 0.25 (that is, the width of the straight conductor is halved), the value of inductance L is about 1. It is only 3 times, and even if b / a is reduced by 1/5 from 0.5 to 0.1 (ie, the width is reduced by 1/5), A is only about 1.8 times. .

On the other hand, in the short-circuit plate 41 branched into two shown in FIG. 3A, the length (effective length) excluding the portion connected to the connecting portions 38 and 42 is l, and the width of each branch path 41a is Assuming w, in the short-circuit plate 41, two branch paths 41a having a width w and a length l are arranged in parallel. At this time, if the inductance of the entire short-circuit plate 41 is L _all and the inductance in the branch path 41a is L _div , the following equation (9) is established.
1 / L _all = 1 / L _div + 1 / L _div (9)
Therefore, from the above equation (9), the inductance of the entire short-circuit plate 41 is half of the inductance of the branch path 41a.

  That is, when the short circuit plate 41 is branched, the inductance in one branch path 41a increases, but in the short circuit board 41, since the two branch paths 41a are arranged in parallel, the path of the high-frequency current can be increased. As a result, the inductance of the entire short-circuit plate 41 can be reduced.

  The short-circuit plate 41 may be branched into three as shown in FIG. That is, the number of branch paths in the short-circuit plate 41 is not limited.

  According to the plasma processing apparatus 40 according to the present embodiment, the short-circuit plate 41 made of a straight conductor having a rectangular cross section is branched into at least two in the middle. If the short-circuit plate 41 is branched, the inductance of the entire short-circuit plate 41 can be reduced as a result. Thereby, the potential of the ground substrate 26 can be lowered, and the potential difference between the ground substrate 26 supporting the lower electrode plate 23 and the inner wall of the chamber 11 can be reduced.

  Next, a plasma processing apparatus according to a third embodiment of the present invention will be described.

  The present embodiment is basically the same in configuration and operation as the first embodiment described above, and is different only in the configuration of the short circuit that short-circuits the ground substrate 26 and the wall surface of the chamber 11. The description of the configuration and operation will be omitted, and different configurations and operations will be described below.

  FIG. 5 is a cross-sectional view schematically showing the configuration of the plasma processing apparatus according to the present embodiment.

  In FIG. 5, the plasma processing apparatus 43 includes a short-circuit plate 44 that short-circuits the ground substrate 26 and the inner wall of the chamber 11. The short-circuit plate 44 is also a thin plate-like conductor having a rectangular cross section made of a conductive material such as metal, for example, stainless steel or Hastelloy (registered trademark).

  One end of the short-circuit plate 44 is connected to a capacitor 45 (another capacitor) provided on the lower surface of the ground substrate 26, and the other end of the short-circuit plate 44 is connected to a capacitor 37 provided at the bottom of the chamber 11. The structure of the capacitor 45 is the same as that of the capacitor 37.

  In this plasma processing apparatus 43, the capacitor 45, the short-circuit plate 44, and the capacitor 37 constitute a short circuit that short-circuits between the ground substrate 26 and the inner wall of the chamber 11. In the plasma processing apparatus 43, the capacitor 37 is interposed between the short-circuit plate 44 and the inner wall of the chamber 11, and the capacitor 45 is interposed between the short-circuit plate 44 and the ground substrate 26. 37 constitutes a series circuit between the ground substrate 26 and the inner wall of the chamber 11.

In the present embodiment, the potential V ₃ of the ground substrate 26 is set to 0 by adjusting the capacitances of the capacitors 37 and 45. Specifically, the capacitance of the capacitor 37 is C1, the self-inductance of the short-circuit plate 44 is L, the capacitance of the capacitor 45 is C2, the frequency of the high frequency power supplied from the high frequency power supply 20 is f, and the high frequency When the angular frequency ω of power is 2πf, the capacitances C1 and C2 of the capacitors 37 and 45 are adjusted so that the following formula (10) is satisfied.
C1 = C2 = 2 / (ω ² × L) (10)
Here, the capacitive reactance of the capacitor 37 and _{X C1,} the capacitive reactance of the capacitor 45 and _{X C2,} the inductive reactance of the short-circuiting plate 44 and _{X L,} the potential _{V 3} is of the formula of the ground substrate 26 (11 ).
V ₃ ≈ (X _C1 + _XL + X _C2 ) × I = (− 1 / (ω × C1) + ω × L−1 / (ω × C2)) × I (11)
Here, from the above equation (10), the potential V ₃ of the ground substrate 26 is expressed by the following equation (12).
V ₃ ≈ (−ω × L / 2 + ω × L−ω × L / 2) × I (12)
That is, the potential _{V 3} 0 of the ground substrate 26.

At this time, the potential V _{C2 of the} capacitor 45 is expressed by the following formula (13).
V _C2 ≈ (X _C1 + X _L ) × I = (− 1 / (ω × C1) + ω × L)) × I (13)
Here, from the above equation (10), the potential V _{C2 of the} capacitor 45 is represented by the following equation (14).
V _C2 ≈ 1/2 × ω × L × I (14)
On the other hand, the potential V ₁ of the ground substrate of the conventional plasma processing apparatus represented by the above formula (5) is represented by the following formula (15) from the above formula (10).
V ₁ ≈ _XL × I = ω × L × I (15)
Therefore, in the present embodiment, the potential V _{C2 of the} capacitor 45 can be ½ of the potential V ₁ of the ground substrate in the conventional plasma processing apparatus.

The potential V _{C1 of the} capacitor 37 is expressed by the following formula (16).
V _C1 ≈ X _C1 × I = −1 / (ω × C1) × I (16)
Here, from the above equation (10), the potential V _{C1 of the} capacitor 45 is represented by the following equation (17).
V _C1 ≈ −1 / 2 × ω × L × I (17)
Therefore, in the present embodiment, the potential V _{C1 of the} capacitor 37 can also be ½ of the potential V ₁ of the ground substrate in the conventional plasma processing apparatus.

According to plasma processing apparatus 43 according to the present embodiment, capacitor 45 is interposed between short-circuit plate 44 and ground substrate 26 in addition to capacitor 37, and capacitor 45 is provided on ground substrate 26. Since C1 = C2 = 2 / (ω ² × L) (the above formula (10)) is established by adjusting the capacitances C1 and C2 of the capacitors 37 and 45, V ₃ ≈ (−1 / ( the ω × C1) + ω × L -1 / (ω × C2)) × I ( the potential _{V 3} of the ground substrate 26 represented by the above formula (11)) can be made zero. Therefore, it is possible to prevent the occurrence of capacitively coupled plasma or abnormal discharge in the vicinity of the ground substrate 26.

Moreover, since it is possible to set the potential _{V C2} and the potential _{V C1} of the capacitor 37 of the capacitor 45 to a half of the potential _{V 1} of the ground substrate in a conventional plasma processing apparatus, between the ground substrate 26 and a capacitor 45, and the capacitor 37 and the inner wall of the chamber 11 can be appropriately reduced, and capacitively coupled plasma and abnormal discharge are generated between the ground substrate 26 and the capacitor 45 and between the capacitor 37 and the inner wall of the chamber 11. Can be suppressed.

  The above-described embodiments may be combined and applied to the plasma processing apparatus. For example, the short-circuit plate 41 branched into two may be used instead of the short-circuit plate 36 in the plasma processing apparatus 10, and the short-circuit plate 41 may be used instead of the short-circuit plate 44 in the plasma processing apparatus 43.

  Although the plasma processing apparatus according to each of the embodiments described above includes the impedance adjustment unit 31, the plasma processing apparatus to which the present invention can be applied is not limited to this, for example, a plasma processing apparatus that does not require the impedance adjustment unit. May be.

  In the plasma processing apparatus according to each of the above-described embodiments, the high frequency power supply 20 is connected to the upper electrode plate 13 of the shower head 12, but the plasma processing apparatus to which the present invention can be applied is not limited thereto. For example, it may be a plasma processing apparatus in which a high frequency power source is connected only to the lower electrode plate 23, or a plasma processing apparatus in which a separate high frequency power source is connected to either the upper electrode plate 13 or the lower electrode plate 23. There may be.

  In the plasma processing apparatus according to each of the above-described embodiments, the ground substrate 26 that supports the lower electrode plate 23 via the lower insulating portion 25 and the short-circuit plate that short-circuits the ground substrate 26 and the inner wall of the chamber 11 are provided. Although provided, the plasma processing apparatus to which the present invention can be applied is not limited to this. For example, the plasma processing apparatus includes a grounding substrate that supports the upper electrode plate via the upper insulating portion and is spaced apart from the inner wall of the chamber 11, and a short-circuit plate that short-circuits the grounding substrate and the inner wall of the chamber. May be.

It is sectional drawing which shows roughly the structure of the plasma processing apparatus which concerns on the 1st Embodiment of this invention. It is sectional drawing which shows schematically the structure of the plasma processing apparatus which concerns on the 2nd Embodiment of this invention. FIG. 3A is a front view showing the short-circuit plate in FIG. 2, FIG. 3A shows a case where the short-circuit plate is branched into two, and FIG. 3B shows a case where the short-circuit plate is branched into three. It is a graph which shows the relationship between the value of the inductance of the linear conductor of a cross-section rectangle which consists of metals, and the width-length ratio in this linear conductor. It is sectional drawing which shows schematically the structure of the plasma processing apparatus which concerns on the 3rd Embodiment of this invention. It is sectional drawing which shows the structure of the conventional plasma processing apparatus roughly.

Explanation of symbols

G Glass substrate S Processing space 10, 40, 43 Plasma processing apparatus 11 Chamber 13 Upper electrode plate 20 High frequency power supply 22 Upper insulating part 23 Lower electrode plate 25 Lower insulating part 26 Grounding substrates 36, 41, 44 Shorting plates 37, 45 Capacitor 37a 45a Insulating layer 41a

Claims (5)

A storage container for storing a substrate, a lower electrode as a mounting table disposed in the storage container for mounting the substrate, and a processing gas supplied to the storage container that is disposed to face the lower electrode An upper electrode, a high-frequency power source connected to at least one of the lower electrode or the upper electrode, and at least one of the lower electrode or the upper electrode are supported via an insulating portion and spaced apart from the inner wall of the container In a plasma processing apparatus comprising: a ground substrate to be disposed; and a short-circuit plate that short-circuits the ground substrate and the inner wall of the container,
A capacitor is interposed between the short-circuit plate and the inner wall of the container, and the capacitor is provided on the inner wall of the container .
The short-circuiting plate in cross-section consists of a rectangular straight conductor, a plasma processing apparatus characterized that you have branched into at least two in the middle. If the capacitive reactance of the capacitor and X _C, the inductive reactance of the short-circuiting plate was X _L,
X _C = −X _L / 2
The plasma processing apparatus according to claim 1, wherein:   The capacitor includes an insulating layer and two conductors sandwiching the insulating layer, and the insulating layer is one selected from the group consisting of a ceramic sheet, a sprayed ceramic layer, and a fluororesin layer. The plasma processing apparatus according to claim 1 or 2. Another capacitor is interposed between the short-circuit plate and the ground substrate, and the other capacitor is provided on the ground substrate,
The capacitance of the capacitor is C1, the self-inductance of the short-circuit plate is L, the capacitance of the other capacitor is C2, the frequency of the high-frequency power supplied by the high-frequency power source is f, and the angular frequency ω is If 2πf,
C1 = C2 = 2 / (ω ² × L)
The plasma processing apparatus according to claim 1, wherein: A storage container for storing a substrate, a lower electrode as a mounting table disposed in the storage container for mounting the substrate, and a processing gas supplied to the storage container that is disposed to face the lower electrode An upper electrode, a high-frequency power source connected to at least one of the lower electrode or the upper electrode, and at least one of the lower electrode or the upper electrode are supported via an insulating portion and spaced apart from the inner wall of the container A short circuit of a high-frequency current for short-circuiting the ground substrate and the inner wall of the container in a plasma processing apparatus comprising a ground substrate disposed;
A short-circuit plate that short-circuits the grounding substrate and the inner wall of the storage container, and a capacitor interposed between the short-circuit plate and the inner wall of the storage container,
The capacitor is provided on the inner wall of the container ,
Short circuit and the short-circuiting plate is that cross section consists of a rectangular straight conductors, characterized that you have branched into at least two in the middle.

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