KR20080093904A - Plasma processing apparatus and high frequency current short circuit - Google Patents

Abstract

A plasma processing apparatus and a high frequency short-circuit apparatus are provided to divide a potential difference between a ground substrate and a wall of a container using a condenser and a short-circuit plate. A plasma processing apparatus includes a container(11), a lower electrode, an upper electrode, a high frequency power source(20), a ground substrate(26), and a short-circuit plate(36). A substrate is contained in the container. The lower electrode is arranged in the container. The substrate is mounted on the lower electrode. The upper electrode is arranged to be opposed to the lower electrode and provides a process gas into the container. The high frequency power source is connected to at least one of the lower and upper electrodes. The ground substrate supports at least one of the lower and upper electrodes with an insulator between them and is arranged to be apart from a wall of the container. The short-circuit plate short-circuits the ground substrate to the wall of the container. A condenser is applied between the short-circuit plate and the wall of the container. The condenser is formed on the wall of the container.

Description

Plasma processing unit and short circuit of high frequency current {PLASMA PROCESSING APPARATUS AND HIGH FREQUENCY CURRENT SHORT CIRCUIT}

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

The plasma processing apparatus 50 which performs an etching process on the glass substrate for liquid crystal panels of the 7th generation and the 8th generation, as shown in FIG. 6, accommodates a glass substrate (henceforth simply a "substrate") G. As shown in FIG. The chamber 51, the lower electrode 52 which mounts the board | substrate G, and the upper electrode 54 of the shower head 53 which oppose the lower electrode 52 are provided. In this plasma processing apparatus 50, plasma is generated by exciting a processing gas supplied to a space between the upper electrode 54 and the lower electrode 52 (hereinafter referred to as a "processing space") by a high frequency electric field, The plasma is subjected to the etching process by the plasma.

In the plasma processing apparatus 50, the lower electrode 52 is supported by the ground substrate 55, and the ground substrate 55 passes through the chamber 56 through the filler 56 and the bellows 57 which are movable in the vertical direction. 51). Since the chamber 51 is grounded, at the time of etching, the upper electrode 54 → plasma in the processing space → lower electrode 52 → ground substrate 55 → pillar 56 → bellows 57 → chamber ( A high frequency current flows through the path of 51). Here, since the pillar 56 and the bellows 57 are made of a conductor, the ground substrate 55 is directly coincident with the chamber 51, but the reactance is caused by the filler 56 or the bellows 57. As it happens, it is not exchangeable coin exchange.

In addition, since the liquid crystal panels of the seventh and eighth generations are very large, the lower electrode 52 and the ground substrate 55 are also very large, and as a result, between the ground substrate 55 and the wall surface of the chamber 51. Space (hereinafter referred to as "lower space") also becomes very large. In addition, since a potential difference is generated between the ground substrate 55 and the wall surface of the chamber 51 which are not alternatingly coincident, a high frequency current may also flow in the lower space to generate a capacitively coupled plasma or an abnormal discharge. The plasma decreases the density of the plasma in the processing space, and the uniformity deteriorates. In addition, the power discharge is lowered due to the abnormal discharge, and the ground substrate 55 is crushed to generate foreign matter.

Therefore, in the plasma processing apparatus 50, the thin-plate short circuit board 58 which consists of an electrically-conductive material which AC-short-circuits the ground surface 55 and the wall surface of the chamber 51 is provided (for example, refer patent document 1). ).

(Patent Document 1) Japanese Patent No. 3710081

However, in order to perform the etching treatment on the liquid crystal panel substrate G of the seventh or eighth generation, it is necessary to supply high power, for example, high frequency power of 10 Hz or more to the processing space. At this time, the high frequency current flowing through the processing space or the ground substrate 55 is 100 A or more. In addition, the shorting plate 58 has a magnetic inductance, and an inductive reactance (impedance) is generated in response to a high frequency current. As a result, the potential of the ground substrate 55 exhibits a high frequency voltage of several 100V.

In order to lower the potential of the ground substrate 55, it is most effective to increase the number of short-circuit boards 58. However, since components such as a lifter pin holder (not shown) are disposed in the lower space, space can be increased. No, it is difficult to increase the number of shorting plates 58.

Therefore, the potential difference between the ground substrate 55 and the wall surface of the chamber 51 is still not solved, and there is a possibility that capacitively coupled plasma or 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 short circuit of a high frequency current capable of reducing the potential difference between the ground substrate supporting at least one of the lower electrode or the upper electrode and the wall of the container.

In order to achieve the above object, the plasma processing apparatus of the first aspect includes an accommodating container for accommodating a substrate, a lower electrode serving as a mounting table disposed in the accommodating container and mounting the substrate, and opposed to the lower electrode. Supporting an upper electrode for supplying a processing gas into the receiving 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 with an insulating portion therebetween, A plasma processing apparatus comprising a ground substrate disposed to be spaced apart from a wall of the accommodating container, and a shorting plate shorting the ground substrate and a wall of the accommodating container, wherein a capacitor is disposed between the shorting plate and the wall of the accommodating container. It is characterized in that the capacitor is provided on the wall of the container.

In the plasma processing apparatus of the second aspect, in the plasma processing apparatus of the first aspect, when the capacitive reactance of the condenser is X _C and the inductive reactance of the shorting plate is X _L , X _C = -X _L / 2 is established.

The plasma processing apparatus of the third aspect is the plasma processing apparatus of the first or second aspect, wherein the capacitor comprises an insulating layer and two conductors holding the insulating layer, and the insulating layer comprises a ceramic sheet, It is characterized in that it is one selected from the group consisting of a sprayed ceramic layer and a fluororesin layer.

In the plasma processing apparatus of the fourth aspect, in the plasma processing apparatus of the first aspect, another capacitor is interposed between the shorting plate and the ground substrate, and the other capacitor is provided on the ground substrate, and the electrostatic charge of the capacitor is provided. The capacitance is set to C1, the magnetic inductance of the shorting plate is set to L, the capacitance of the other capacitor is set to C2, the frequency of the high frequency power supplied by the high frequency power source is set to f, and the angular frequency ω is set to 2πf. In this case, C1 = C2 = 2 / (ω ² × L) is established.

In order to achieve the above object, the plasma processing apparatus of the fifth aspect includes a housing container housing a substrate, a lower electrode serving as a mounting table disposed in the storage container, and mounted thereon, and facing the lower electrode. Supporting an upper electrode for supplying a processing gas into the receiving 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 with an insulating portion therebetween, A plasma processing apparatus comprising a ground substrate disposed apart from a wall of the housing container, and a short circuit board shorting the ground substrate and the wall of the housing container, wherein the short circuit board is formed of a straight conductor having a rectangular cross section. It is characterized by branching into at least two on the way.

The plasma processing apparatus of the sixth aspect is the plasma processing apparatus of the fifth aspect, wherein a capacitor is interposed between the shorting plate and the wall of the housing container, and the capacitor is provided on the wall of the housing container. .

In order to achieve the above object, the short-circuit of the high frequency current of the seventh aspect includes an accommodating container accommodating a substrate, a lower electrode serving as a mounting base disposed in the accommodating container, and mounting the substrate; An upper electrode arranged to supply a processing gas into the accommodating container, a high frequency power source connected to at least one of the lower electrode or the upper electrode, and supporting at least one of the lower electrode or the upper electrode with an insulating portion therebetween; And a short circuit of a high frequency current for shorting the ground substrate and the wall of the housing container, wherein the ground substrate is disposed apart from the wall of the housing container. A shorting plate for shorting a wall of the condenser, and a condenser interposed between the shorting plate and the wall of the receiving container. To have, the capacitor is characterized in that it is provided in the wall of the containment vessel.

In order to achieve the above object, the short circuit of the high frequency current of the eighth aspect includes an accommodating container accommodating a substrate, a lower electrode serving as a mounting table disposed in the accommodating container, and mounting the substrate, An upper electrode arranged to supply a processing gas into the accommodating container, a high frequency power source connected to at least one of the lower electrode or the upper electrode, and supporting at least one of the lower electrode or the upper electrode with an insulating portion therebetween; And a short circuit of a high frequency current for shorting the ground substrate and the wall of the housing container, wherein the ground substrate is disposed apart from the wall of the housing container. Has a shorting plate for shorting the walls of the shorting plate, the shorting plate consisting of a straight conductor having a rectangular cross section And, it characterized in that at least two branches on the way.

According to the plasma processing apparatus of the first aspect and the short circuit of the high frequency current of the seventh aspect, the ground substrate and the accommodating container are interposed between the shorting plate which shorts the wall of the ground substrate and the accommodating container and the wall of the accommodating container. The potential difference between the walls of can be shared by a shorting plate and a capacitor. In addition, since the capacitor is provided on the wall of the container, the potential difference between the ground substrate and the wall of the container is substantially a potential difference between the ground substrate and the capacitor, and the potential difference is a potential difference shared by the shorting plate. Therefore, the potential difference between the ground substrate which supports at least one of the lower electrode or the upper electrode and the wall of the housing 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 shorting plate satisfy X _C = -X _L / 2. If 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 wall of the accommodating container is represented by V ₁ ≒ X _L × I, The potential V ₂ of the ground substrate when the capacitor is interposed between the walls is represented by V ₂ ≒ (X _L + X _C ) × I. Since X _C = -X _L / 2 holds, V ₂ ≒ 1/2 × X _L × I. That is, it is possible to set the V ₂ to a half of V _1, it is possible to surely reduce the potential for short-circuiting plate is shared. At this time, the potential difference shared by the capacitor is also 1/2 of V ₁ , so that the potential difference between the ground substrate and the capacitor and between the capacitor and the wall of the container can be appropriately reduced, and the ground substrate and The generation of capacitively coupled plasma or abnormal discharge can be suppressed between the capacitors and between the capacitor and the wall of the container.

According to the plasma processing apparatus of the fourth aspect, another capacitor is interposed between the short circuit board and the ground substrate, and the other capacitor is provided on the ground substrate, and the capacitance C1 of the capacitor, the magnetic inductance L of the short circuit board, and the static electricity of the other capacitor are provided. The angular frequency ω (= 2πf) when the capacitance C2 and the frequency of the high frequency power is f satisfies C1 = C2 = 2 / (ω ² × L). If the high-frequency current is I, the potential V ₃ of the grounding substrate when the capacitor is interposed between the shorting plate and the wall of the housing vessel and another capacitor is interposed between the shorting plate and the grounding substrate is the capacitive reactance of the capacitor. Is X _C1 , the capacitive reactance of another capacitor is X _C2 , and the inductive reactance of the shorting plate is X _L , which is represented by V ₃ ≒ (X _C1 + X _L + X _C2 ) × I, and When expanded, the potential V ₃ is represented by V ₃ ≒ (−1 / (ω × C1) + ω × L-1 / (ω × C2)). Since C1 = C2 = 2 / (ω ² × L) holds, V 3 ≒ 0 is obtained. That is, since the potential of the ground substrate can be zero, the generation of a capacitively coupled plasma or an abnormal discharge can be prevented in the vicinity of the ground substrate.

According to the plasma processing apparatus of the fifth aspect and the short circuit of the high frequency current of the eighth aspect, the shorting plate that shorts the ground substrate and the wall of the receiving container is made of a straight conductor having a rectangular cross section, and branches to at least two on the way. have. When the shorting plates are branched, the cross-sectional area to each branch is reduced, but the path of the high frequency current can be increased, and as a result, the inductance of the entire shorting plate can be reduced. Thereby, the potential of a ground substrate can be reduced, and the potential difference between the ground substrate which supports at least one of a lower electrode or an upper electrode, and the wall of a storage container can be reduced.

According to the plasma processing apparatus of the sixth aspect, since a capacitor is interposed between the shorting plate and the wall of the housing, the potential difference between the ground board and the wall of the housing can be shared by the shorting plate and the capacitor, so that The potential difference between the walls of the receiving container can be further reduced.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described, referring drawings.

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

1 is a cross-sectional view schematically showing the configuration of a plasma processing apparatus according to the present embodiment. This plasma processing apparatus is comprised so that an etching process may be performed to the glass substrate for liquid crystal displays (LCD).

In FIG. 1, the plasma processing apparatus 10 includes, for example, a cylindrical chamber 11 (a container) for accommodating a rectangular glass substrate (hereinafter, simply referred to as a “substrate”) G having one side of about 1 m. Have The chamber 11 is made of aluminum, and most of the walls of the chamber 11 are covered with alumite.

The shower head 12 (upper electrode) is arrange | positioned in the ceiling part of the chamber 11, The shower head 12 attaches the upper electrode plate 13 which is a rectangular conductive flat plate, and the upper electrode plate 13 to it. It has the upper electrode base part 14 which consists of a conductor which detachably supports. A buffer chamber 15 is provided inside the upper electrode base portion 14, and a processing gas introduction pipe 16 is connected to the buffer chamber 15. In addition, the upper electrode plate 13 has a plurality 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 device (not shown), and the processing gas supply device introduces the processing gas into the buffer chamber 15 via the processing gas introduction pipe 16. The shower head 12 has a space between the upper electrode plate 13 and the lower electrode plate 23 described later via the gas hole 17 for the processing gas introduced into the buffer chamber 15 (hereinafter referred to as “process space S”). Is referred to as "." Here, since the shower head 12 is supported from the ceiling of the chamber 11 with the upper insulating part 22 interposed therebetween, the shower head 12 is fully electrically floating from the chamber 11.

The upper electrode plate 13 is connected to the high frequency power supply 20 via the upper electrode base 14, the matching circuit 18, and the conductive path 19. In addition, on the ceiling of the chamber 11, a matching box 21 is provided to surround the matching circuit 18. Since the matching box 21 is grounded, it functions as a grounding housing of the matching circuit 18. The high frequency power supply 20 supplies a predetermined high frequency power, for example, 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 a plasma. As the processing gas, for example, a gas containing halogen, specifically, a gas composed of a halogen compound, an oxygen gas, an argon gas, or the like can be used.

At the bottom of the chamber 11, a rectangular lower electrode plate 23 serving as a mounting table on which the substrate G is mounted is disposed. The lower electrode plate 23 faces the upper electrode plate 13 and is supported by a ground substrate 26 made of aluminum with the lower insulating portion 25 interposed therebetween. In addition, the ground substrate 26 is disposed apart from the bottom of the chamber 11 and is supported by a cylindrical filler 27. The filler 27 is arrange | positioned on the support plate 28 which moves to an up-down direction (arrow direction in drawing) by the drive mechanism which is not shown in figure. Therefore, the ground substrate 26 and the lower electrode plate 23 also move up and down as the support plate 28 moves up and down. The support plate 28 is connected to the bottom of the chamber 11 via the bellows 29, and the bellows 29 hermetically partitions the chamber 11 and the outside of the chamber 11. In addition, the filler 27, the support plate 28, and the bellows 29 are all made of a conductor.

A chiller flow path (not shown) is provided in the lower electrode plate 23, and the substrate G mounted on the lower electrode plate 23 is cooled by the refrigerant flowing through the chiller flow path. The lower insulator 25 is made of a dielectric or an atmospheric layer, and the lower electrode plate 23 is electrically floated sufficiently from the ground substrate 26 and, furthermore, the chamber 11.

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

An exhaust path 32 is connected to the bottom of the chamber 11, and an exhaust device not shown, for example, a turbo molecular pump or a dry pump, is connected to the exhaust path 32. The exhaust device exhausts the inside of the chamber 11 via the exhaust passage 32. Moreover, the gate valve 34 which opens and closes the conveyance port 33 of the board | substrate G is provided in the side wall of the chamber 11.

In the plasma processing apparatus 10, the high frequency power supply 20 → matching circuit 18 → shower head 12 → plasma in the processing space S → lower electrode plate 23 → impedance adjustment unit 31 → chamber 11 → Although a high frequency current flows from the matching box 21 to the ground path, there is a possibility that a high frequency current flows shortly from the shower head 12 through the plasma to the wall of the chamber 11, and thus from the lower electrode plate 23, The impedance of the path (return path) to the matching box 21 is adjusted by the impedance adjusting unit 31 to prevent the high frequency current from flowing shortly in the wall portion of the chamber 11.

In the plasma processing apparatus 10, by supplying a high frequency electric power to the processing space S to generate a high frequency electric field, the plasma processing apparatus 10 excites the processing gas supplied from the shower head 12 in the processing space S to generate a high density plasma. The plasma is subjected to the etching process by the plasma.

In addition, the operation of each component of the plasma processing apparatus 10 is controlled by a CPU of a control unit (not shown) included in the plasma processing apparatus 10 in accordance with a program corresponding to an etching process.

In addition, the plasma processing apparatus 10 includes a short circuit plate 36 for shorting the ground substrate 26 and the wall of the chamber 11, and a capacitor interposed between the short circuit plate 36 and the wall of the chamber 11. (37) is provided. The short-circuit board 36 is a rectangular cross-sectional conductor of a rectangular cross section, which is made of a conductive material such as metal, for example, stainless steel or Hastelloy (registered trademark).

One end of the shorting plate 36 is connected to the bottom surface of the ground substrate 26 via a connecting portion 38, and the other end of the shorting plate 36 is a wall of the chamber 11, specifically, of the chamber 11. It is connected to the capacitor | condenser 37 provided in the bottom part.

The capacitor | condenser 37 consists of the insulating layer 37a and two metal plates 37b and 37c, such as an aluminum plate which hold | maintains the insulating layer 37a, and the part which may be in contact with a plasma is alumite etc. Covered with an insulating film. In addition, the insulating layer 37a consists of a ceramic sheet, a thermal sprayed ceramic layer, and a fluororesin layer (Teflon (trademark) layer), for example. As the condenser 37, a commercially available vacuum condenser and a variable capacitor condenser having plasma resistance can be used in addition to the above-described embodiment.

In this plasma processing apparatus 10, the shorting plate 36 and the condenser 37 constitute a short circuit that shorts between the ground substrate 26 and the wall of the chamber 11.

In the plasma processing apparatus 10, when the high frequency current flows between the ground substrate 26 and the wall of the chamber 11, the short circuit plate 36 has a magnetic inductance, and thus the inductive reactance is applied to the short circuit plate 36. In addition, since the capacitor 37 has a capacitance, a capacitive reactance is generated in the capacitor 37. Moreover, in the plasma processing apparatus 10, since the capacitor | condenser 37 is interposed between the short circuit board 36 and the wall of the chamber 11, the short circuit board 36 and the capacitor | condenser 37 are connected with the ground board 26 and A series circuit is constructed between the walls of the chamber 11. Therefore, the short circuit board 36 and the capacitor | condenser 37 can share the potential difference which arises when a high frequency electric current flows between the ground board 26 and the wall of the chamber 11.

Here, the potential V ₂ of the ground substrate 26 sets the wall of the chamber 11 to the ground potential, sets the impedance of the short circuit plate 36 to Z _L , sets the impedance of the capacitor 37 to Z _C , If the high frequency current flowing between the ground substrate 26 and the wall of the chamber 11 is I, it is represented by the following formula (1).

V ₂ = (Z _L + Z _C ) × I... (One)

Normally, Z _L and Z _C are represented by R + jX (X is reactance). However, in the plasma processing apparatus 10, R is very small compared with X and can be ignored. Therefore, in the present embodiment, if the inductive reactance of the short circuit plate 36 is X _L and the capacitive reactance of the capacitor 37 is X _C , the potential V ₂ of the ground substrate 26 is represented by the following equation (2). Is indicated by).

V ₂ ≒ (X _L + X _C ) × I... (2)

In this 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 equation (3) holds.

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 × X _L × I... (4)

On the other hand, as in the conventional plasma processing apparatus, when the ground substrate and the walls of the chamber are short-circuited only by the short circuit board, the potential V ₁ of the ground substrate is represented by the following formula (5).

V ₁ ≒ X _L × I... (5)

Comparing the above formulas (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 the conventional plasma processing apparatus. Therefore, the capacitor 37 is interposed between the short-circuit plate 36 and the wall of the chamber 11, and the electric potential of the ground substrate 26 is adjusted by adjusting the capacitance of the capacitor 37 so that the above equation (3) holds. V ₂ can be 1/2 of the potential V ₁ of the ground substrate in the conventional plasma processing apparatus.

In addition, the potential V _C of the capacitor | condenser 37 is represented by following formula (6) at this time.

V _C ≒ X _C × I... (6)

Here, in the above formula (3), the potential V _C of the condenser 37 is represented by the following formula (7).

V _C ≒ -1 / 2 x X _L x I... (7)

Therefore, the potential V _C of the capacitor 37 can also be 1/2 of the potential V ₁ of the ground substrate in the conventional plasma processing apparatus. In other words, the potential difference shared by the capacitor 37 is also 1/2 of V ₁ .

According to the plasma processing apparatus 10 according to the present embodiment, the short-circuit plate 36 and the capacitor 37 have a potential difference generated when a high frequency current flows between the ground substrate 26 and the wall of the chamber 11. Can share In addition, since the condenser 37 is provided on the wall of the chamber 11, the potential difference between the ground substrate 26 and the wall of the chamber 11 is substantially reduced between the ground substrate 26 and the condenser 37. It is a potential difference, and this potential difference is the potential difference which the short circuit board 36 shares. Therefore, the potential difference between the ground substrate 26 supporting the lower electrode plate 23 and the wall of the chamber 11 can be reduced.

In the above-described plasma processing apparatus 10, X _C = -X _L / 2 (Equation (3)) is established by adjusting the capacitance of the capacitor 37, so that the potential V ₂ of the ground substrate 26 is V. _{It is represented by 2} ≒ 1/2 × X _L × I (Equation (4) above). On the other hand, the potential V ₁ of the ground substrate of the conventional plasma processing apparatus is represented by V ₁ ≒ X _L × I (Equation (5) above). That is, V ₂ can be made 1/2 of V ₁ , and the potential difference shared by the short circuit plate 36 can be reliably reduced.

In addition, since the potential difference shared by the condenser 37 is also 1/2 of V ₁ , the potential difference between the ground substrate 26 and the condenser 37 and between the condenser 37 and the wall of the chamber 11 is reduced. It can reduce suitably and can suppress generation | occurrence | production of a capacitive coupling plasma and abnormal discharge between the ground substrate 26 and the capacitor | condenser 37, or between the wall of the capacitor | condenser 37 and the chamber 11 can be suppressed.

In the plasma processing apparatus 10 described above, but the electric potential V ₂ of the ground substrate 26 by adjusting the capacitance of the condenser 37 to a former half of the above V ₁ of the ground substrate in the conventional plasma processing apparatus By adjusting the capacitance of the capacitor 37, the potential difference shared by the short circuit plate 36 may be changed, and the potential V ₂ of the ground substrate 26 may be set to almost zero.

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

The present embodiment is basically the same as that of the first embodiment described above, and the configuration of the short circuit for shorting the wall surface of the ground substrate 26 and the chamber 11 is different. The description will be omitted, and other structures and operations will be described below.

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

2, the plasma processing apparatus 40 is provided with the short circuit board 41 which short-circuits the ground board 26 and the wall of the chamber 11. As shown in FIG. The short-circuit board 41 is also a thin rectangular cross-sectional conductor made of a conductive material such as metal, for example, stainless steel or Hastelloy (registered trademark).

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

3: is a front view which shows the short circuit board in FIG. 2, FIG. 3 (a) shows the case where 2 short boards were branched, and FIG. 3 (b) shows the case where 3 short circuit boards were branched.

In general, the inductance L of a rectangular cross-sectional conductor made of metal is expressed by the following formula (8) when the length of the linear conductor is a (cm), the width is b (cm), and the thickness is c (cm). do.

L = 0.002a × [2.303 × log {2a / (b + c)} + 0.5 + 0.2235 × (b + c) / a... (8)

Here, when b >> c, the above formula (8) is represented by the following formula (8) '.

L ≒ 0.002a × {2.303 × log (2a / b) + 0.5 + 0.2235 × b / a}... (8)'

At this time, when the value of L in said Formula (8) 'is set to A, and the width-length ratio in a linear conductor is b / a, the relationship of A and b / a becomes as shown in FIG. . 4, the horizontal axis represents the width-length ratio b / a, and the vertical axis corresponds to each width-length ratio b / a with A as 1 when the width-length ratio b / a is 0.5. Normalized A in the case where 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 A of inductance L is only about 1.3 times, and b / a is reduced to 0.5. A 1/5 reduction to 0.1 (i.e. a 1/5 reduction in width) would only cause A to be about 1.8 times.

On the other hand, in two short-circuit boards 41 shown in Fig. 3 (a), the length (effective length) excluding the portion connected to the connecting portions 38 and 42 is referred to as l, and each branch path 41a is If the width is w, the shorting plate 41 has two branch paths 41a having a width w and a length l arranged in parallel. At this time, if the inductance of the entirety of the short circuit plate 41 is referred to as L _all , and the inductance in the branch path 41a is referred to as L _div , the following formula (9) is established.

1 / L _all = 1 / L _div + 1 / L _div ... (9)

Therefore, in the above formula (9), the inductance of the entire shorting plate 41 is half of the inductance of the branch path 41a.

That is, when the shorting plate 41 branches, the inductance in one branch path 41a increases, but in the shorting plate 41, since two branch paths 41a are arranged in parallel, the path of the high frequency current is changed. It can increase, and as a result, the inductance of the whole short circuit board 41 can be reduced.

Moreover, you may branch into three short circuit boards 41, as shown to FIG. 3 (b). 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 plates 41 each having a rectangular straight conductor in cross section are branched into at least two on the way. When the shorting plate 41 is branched, the inductance of the entire shorting plate 41 can be reduced as a result. Thereby, the potential of the ground substrate 26 can be reduced, and the potential difference between the ground substrate 26 supporting the lower electrode plate 23 and the 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 as that of the first embodiment described above, and the configuration of the short circuit for shorting the ground surface of the ground substrate 26 and the chamber 11 differs only from the above. The description of the operation is omitted, and other configurations and operations will be described below.

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

5, the plasma processing apparatus 43 is provided with the short circuit board 44 which short-circuits the ground board 26 and the wall of the chamber 11. As shown in FIG. The short-circuit board 44 is also a thin rectangular cross-sectional conductor 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 condenser 45 (another condenser) provided on the bottom surface of the ground substrate 26, and the other end of the short circuit plate 44 is provided with a condenser provided at the bottom of the chamber 11 ( 37). The structure of the condenser 45 is the same as that of the condenser 37.

In this plasma processing apparatus 43, the capacitor | condenser 45, the short circuit board 44, and the capacitor | condenser 37 comprise the short circuit which short-circuites between the ground board 26 and the wall of the chamber 11. In the plasma processing apparatus 43, the capacitor 37 is interposed between the short circuit plate 44 and the wall of the chamber 11, and the capacitor 45 is interposed between the short circuit plate 44 and the ground substrate 26. Since it interposes, the capacitor | condenser 45, the short circuit board 44, and the capacitor | condenser 37 comprise a series circuit between the ground board 26 and the wall of the chamber 11.

In this embodiment, the potential V ₃ of the ground substrate 26 is set to zero by adjusting the capacitances of the capacitors 37 and 45. Specifically, the capacitance of the capacitor 37 is set to C1, the magnetic inductance of the shorting plate 44 is set to L, the capacitance of the capacitor 45 is set to C2, and the high frequency power source 20 supplies the high frequency. When the frequency of the power is f and the angular frequency ω of the high frequency power is 2 pi, the capacitances C1 and C2 of the capacitors 37 and 45 are adjusted so that the following equation (10) holds.

C1 = C2 = 2 / (ω ² × L). 10

Here, when the capacitive reactance of the condenser 37 is X _C1 , the capacitive reactance of the condenser 45 is X _C2 , and the inductive reactance of the short circuit board 44 is X _L , the ground substrate 26 is used. The potential V _{3 of} is represented by the following formula (11).

V ₃ ≒ (X _C1 + X _L + X _C2 ) × I = (− 1 / (ω × C1) + ω × L-1 / (ω × C2)) × I... (11)

Here, in the above formula (10), the potential V ₃ of the ground substrate 26 is represented by the following formula (12).

V ₃ ≒ (−ω × L / 2 + ω × L-ω × L / 2) × I... (12)

In other words, the potential V ₃ of the ground substrate 26 becomes zero.

In addition, the potential V _C2 of the capacitor | condenser 45 is represented by following formula (13) at this time.

V _C2 ≒ (X _C1 + X _L ) × I = (− 1 / (ω × C1) + ω × L)) × I... (13)

Here, in the above formula (10), the potential V _C2 of the capacitor 45 is represented by the following formula (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) in the above formula (10).

V ₁ x X _L x I = ω x L x I... (15)

Therefore, in the present embodiment, the potential V _C2 of the capacitor 45 can be set to 1/2 of the potential V ₁ of the ground substrate in the conventional plasma processing apparatus.

In addition, the potential V _C1 of the capacitor 37 is represented by the following formula (16).

V _C1 x X _C1 x I = -1 / (ω x C1) x I... (16)

Here, in the above formula (10), the potential V _C1 of the capacitor 45 is represented by the following formula (17).

V _C1 ? -1/2 x? (17)

Therefore, in this embodiment, the potential V _C1 of the capacitor 37 can also be 1/2 of the potential V ₁ of the ground substrate in the conventional plasma processing apparatus.

According to the plasma processing apparatus 43 according to the present embodiment, in addition to the capacitor 37, a capacitor 45 is interposed between the short circuit plate 44 and the ground substrate 26, and the capacitor 45 is a ground substrate. It is provided at 26. Further, by adjusting the capacitances C1 and C2 of the capacitors 37 and 45, C1 = C2 = 2 / (ω ² x L) (Equation (10)) is established, so that V ₃ ≒ (-1 / (ω x) The potential V ₃ of the ground substrate 26 represented by C1) + ω × L-1 / (ω × C2)) × I (Equation (11)) can be zero. Therefore, generation of capacitively coupled plasma or abnormal discharge in the vicinity of the ground substrate 26 can be prevented.

Can also be obtained when the electric potential of the electric potential V _C1 and V _C2 capacitor 37 of the capacitor 45 to a half of the electric potential V ₁ of the ground substrate in the conventional plasma processing apparatus, the ground substrate 26, and a capacitor ( All of the potential difference between the 45 and between the capacitor 37 and the wall of the chamber 11 can be appropriately reduced, and between the ground substrate 26 and the capacitor 45 or between the capacitor 37 and the chamber 11. The generation of capacitively coupled plasma or abnormal discharge can be suppressed between the walls.

Each of the above-described embodiments may be applied to the plasma processing apparatus in combination. For example, in the plasma processing apparatus 10, two short-circuit plates 41 may be used instead of the short-circuit plate 36, and in the plasma processing apparatus 43, a short-circuit plate 44 may be short-circuited. The plate 41 may be used.

Although the plasma processing apparatus according to each of the above-described embodiments includes an impedance adjusting unit 31, the plasma processing apparatus to which the present invention can be applied is not limited thereto, and for example, the plasma processing apparatus does not require the impedance adjusting unit. It may be.

In the plasma processing apparatuses according to the above-described embodiments, the high frequency power source 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. Do not. For example, the plasma processing apparatus may be a high frequency power supply connected only to the lower electrode plate 23, or the plasma processing apparatus may be a high frequency power supply connected to both the upper electrode plate 13 and the lower electrode plate 23. .

In the plasma processing apparatus according to the above-described embodiments, the ground substrate 26 supporting the lower electrode plate 23 with the lower insulation portion 25 interposed therebetween, the ground substrate 26, and the chamber 11. Although the short circuit board which shorts the wall of) was provided, the plasma processing apparatus which can apply this invention is not limited to this. For example, the plasma processing apparatus may include a ground substrate which supports the upper electrode plate with the upper insulation portion interposed therebetween and is spaced apart from the wall of the chamber 11, and a shorting plate that shorts the ground substrate and the wall of the chamber. .

1 is a cross-sectional view schematically showing the configuration of a plasma processing apparatus according to a first embodiment of the present invention;

2 is a cross-sectional view schematically showing the configuration of a plasma processing apparatus according to a second embodiment of the present invention;

3 is a front view showing a short circuit board in FIG. 2, FIG. 3 (a) shows a case where the short circuit board is divided into two, and FIG. 3 (b) shows a case where the short circuit board is divided into three,

4 is a graph showing a relationship between an inductance value of a linear conductor of a rectangular cross section made of metal and a width-length ratio in the linear conductor;

5 is a cross-sectional view schematically showing the configuration of a plasma processing apparatus according to a third embodiment of the present invention;

6 is a cross-sectional view schematically showing the configuration of a conventional plasma processing apparatus.

Explanation of symbols for the main parts of the drawings

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 insulation portion 23: lower electrode plate

25: lower insulation portion 26: ground substrate

36, 41, 44: short circuit 37, 45: capacitor

37a, 45a: insulating layer 41a: branch furnace

Claims (10)

An accommodating container for accommodating a substrate, a lower electrode serving as a mounting table disposed in the accommodating container, on which the substrate is mounted, an upper electrode disposed to face the lower electrode, and for supplying a processing gas into the accommodating container; A high frequency power source connected to at least one of the electrode or the upper electrode, a ground substrate disposed at a distance from the wall of the housing container while supporting at least one of the lower electrode or the upper electrode with an insulating portion interposed therebetween; A plasma processing apparatus comprising a shorting plate for shorting a ground substrate and a wall of the container. A condenser is interposed between the shorting plate and the wall of the receiving container, The condenser is provided on a wall of the container Plasma processing apparatus, characterized in that. The method of claim 1, When the capacitive reactance of the capacitor is X _C and the inductive reactance of the shorting plate is X _L , X _C = -X _L / 2 The plasma processing apparatus characterized by the above-mentioned. The method according to claim 1 or 2, The capacitor is composed of an insulating layer and two conductors holding the insulating layer therebetween, And said insulating layer is one selected from the group consisting of a ceramic sheet, a thermal spray ceramic layer and a fluororesin layer. The method of claim 1, Another capacitor is interposed between the shorting plate and the ground substrate, the other capacitor is provided on the ground substrate, The capacitance of the capacitor is C1, the magnetic inductance of the shorting plate is L, the capacitance of the other capacitor is C2, the frequency of the high frequency power supplied by the high frequency power supply is f, and the angular frequency is ω. If is set to 2πf, C1 = C2 = 2 / plasma processing apparatus characterized in that the (ω ² × L) is satisfied. An accommodating container for accommodating a substrate, a lower electrode serving as a mounting table disposed in the accommodating container, on which the substrate is mounted, an upper electrode disposed to face the lower electrode, and for supplying a processing gas into the accommodating container; A high frequency power source connected to at least one of the electrode or the upper electrode, a ground substrate disposed at a distance from the wall of the housing container while supporting at least one of the lower electrode or the upper electrode with an insulating portion interposed therebetween; A plasma processing apparatus comprising a shorting plate for shorting a ground substrate and a wall of the container. Said short-circuit board consists of straight conductors of rectangular cross section, branched into at least two on the way Plasma processing apparatus, characterized in that. The method of claim 5, wherein A condenser is interposed between the shorting plate and the wall of the accommodating container, and the condenser is provided on the wall of the accommodating container. The method according to claim 1 or 5, And the wall of the container is an inner wall of the container. An accommodating container for accommodating a substrate, a lower electrode serving as a mounting table disposed in the accommodating container, on which the substrate is mounted, an upper electrode disposed to face the lower electrode, and for supplying a processing gas into the accommodating container; And a high-frequency power source connected to at least one of the electrodes or the upper electrode, and a ground substrate disposed at a distance from the wall of the accommodating container while supporting at least one of the lower electrode or the upper electrode with an insulating portion therebetween. In a plasma processing apparatus, as a short circuit of the high frequency electric current which short-circuits the wall of the said ground substrate and the said accommodating container, A shorting plate for shorting the ground substrate and a wall of the container, and a capacitor interposed between the shorting plate and the wall of the container, The condenser is provided on a wall of the container Short circuit of high frequency current, characterized in that. An accommodating container for accommodating a substrate, a lower electrode serving as a mounting table disposed in the accommodating container, on which the substrate is mounted, an upper electrode disposed to face the lower electrode, and for supplying a processing gas into the accommodating container; And a high-frequency power source connected to at least one of the electrode or the upper electrode, and a ground substrate disposed at a distance from the wall of the housing container while supporting at least one of the lower electrode or the upper electrode with an insulating portion therebetween. As a short circuit of the high frequency electric current which shorts the wall of the said ground substrate and the said accommodating container in a plasma processing apparatus, A short circuit board shorting the ground substrate and a wall of the container, Said short-circuit board consists of straight conductors of rectangular cross section, branched into at least two on the way Short circuit of high frequency current, characterized in that. The method according to claim 8 or 9, And the wall of the housing container is an inner wall of the housing container.

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