Plasma processing apparatus and reaction tube wall protecting member

Abstract

To provide a plasma processing apparatus which suppresses consumption of a reaction tube.SOLUTION: A reaction tube having a cylindrical shape; a substrate holder configured to hold a plurality of substrates to be inserted into and removed from the reaction tube; a pair of electrodes disposed outside the reaction tube and facing each other with respect to a center of the reaction tube; a high frequency power source configured to apply high frequency power to one or both of the pair of electrodes to generate plasma in the reaction tube; A pair of reaction tube wall protecting members including a first reaction tube wall protecting member disposed between one electrode and the substrate holder and a second reaction tube wall protecting member disposed between the other electrode and the substrate holder, wherein the pair of reaction tube wall protecting members cover an inner wall surface opposite to an outer wall surface of the reaction tube on which the pair of electrodes are installed.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a plasma processing apparatus and a reactor wall protection member. [Background technology]

[0002] Patent Document 1 discloses a plasma processing apparatus having a plasma generating unit extending in the height direction of a reaction tube. It also describes that the plasma generating unit includes a hollow protrusion and a pair of plasma electrodes disposed on a pair of wall surfaces of the hollow protrusion. It also discloses that large stress occurs on the wall surface of the hollow protrusion at and near the outline of the plasma electrode due to sputtering or etching by plasma. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4329403 Summary of the Invention [Problem to be solved by the invention]

[0004] In one aspect, the present disclosure provides a plasma processing apparatus and a reaction tube wall protection member that suppress wear of a reaction tube. [Means for solving the problem]

[0005] In order to solve the above problems, according to one aspect, there is provided a plasma processing apparatus for plasma processing substrates in the reaction tube, comprising: a cylindrical reaction tube; a substrate holder for mounting a large number of substrates in multiple stages to be inserted into or removed from the reaction tube; a pair of electrodes arranged outside the reaction tube and facing each other with respect to the center of the reaction tube; a high-frequency power supply for applying high-frequency power to one or both of the pair of electrodes to generate plasma in the reaction tube; and a pair of reaction tube wall protecting members arranged between the pair of electrodes, the pair of reaction tube wall protecting members including a first reaction tube wall protecting member arranged between one of the electrodes and the substrate holder and a second reaction tube wall protecting member arranged between the other electrode and the substrate holder, wherein the pair of reaction tube wall protecting members cover inner wall surfaces opposite to outer wall surfaces of the reaction tube on which the pair of electrodes are installed. [Effects of the Invention]

[0006] According to one aspect, it is possible to provide a plasma processing apparatus and a reaction tube wall protection member that suppress wear of a reaction tube. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a vertical cross-sectional view showing an example of a plasma processing apparatus. [Figure 2] 1 is a longitudinal cross-sectional view taken along arrow A, showing an example of a plasma processing apparatus. [Figure 3] FIG. 1 is a cross-sectional view showing an example of a plasma processing apparatus taken along the cross section BB. [Figure 4] FIG. 2 is a longitudinal sectional view of a reaction tube in which a reaction tube wall protection member is disposed. [Figure 5] FIG. 2 is a front view of a reaction tube wall protection member as viewed from the radially outer side of the reaction tube. [Figure 6] FIG. 2 is a top view of a reaction tube wall protection member. [Figure 7] FIG. 2 is a cross-sectional view showing an example of the arrangement of a reaction tube and a reaction tube wall protection member. [Figure 8] 1 is a graph showing an example of a Paschen curve. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant explanations may be omitted.

[0009] [Plasma Processing Apparatus] A plasma processing apparatus (substrate processing apparatus) according to this embodiment will be described with reference to FIGS. 1 to 3. FIG. 1 is a longitudinal cross-sectional view showing an example of the plasma processing apparatus. FIG. 2 is a view taken along the arrow A in FIG. 1 and shows an example of the plasma processing apparatus. FIG. 3 is a cross-sectional view showing an example of the plasma processing apparatus taken along the cross section BB in FIG. 2. The plasma processing apparatus shown in FIGS. 1 to 3 is a batch-type plasma processing apparatus that performs substrate processing (e.g., film formation processing) on ​​a plurality of substrates W. Note that a reaction tube wall protection member 100 (reaction tube wall protection plate 110), which will be described later, is not shown in FIGS. 1 and 2.

[0010] The plasma processing apparatus has a cylindrical reaction tube (also called a processing vessel or reactor) 1 with a ceiling and an open lower end. The entire reaction tube 1 is made of, for example, quartz. A ceiling plate 2 made of quartz is provided near the upper end of the reaction tube 1, and the area below the ceiling plate 2 is sealed.

[0011] The reaction tube 1 has a cylindrical shape (a cylindrical shape) that is closed at the top. The reaction tube 1 is open at the bottom, and a wafer boat (substrate holder) 3 carrying a large number of semiconductor wafers (for example, several to about 100 wafers) (hereinafter referred to as "substrates W") as substrates to be processed in multiple stages is inserted into the reaction tube 1 from the bottom of the reaction tube 1. In this way, the reaction tube 1 is provided with a gap L in the vertical direction. W The wafer boat 3 has a space 1c and accommodates a large number of substrates W in a substantially horizontal position. The wafer boat 3 is made of, for example, quartz. The wafer boat 3 has four rods 4 (see FIG. 3; two are shown in FIGS. 1 and 2), and grooves (not shown) formed in the rods 4 support the large number of substrates W.

[0012] The wafer boat 3 is placed on a table 6 via a heat-retaining cylinder 5 made of quartz. The table 6 is supported on a rotation shaft 8 that passes through a metal (stainless steel) cover 7 that opens and closes the opening at the bottom end of the reaction tube 1.

[0013] A magnetic fluid seal 9 is provided at the penetration part of the rotating shaft 8 to airtightly seal and rotatably support the rotating shaft 8. A seal member 10 is provided between the peripheral part of the lid 7 and the lower end of the reaction tube 1 to maintain airtightness inside the reaction tube 1.

[0014] The rotation shaft 8 is attached to the tip of an arm 11 supported by a lifting mechanism (not shown) such as a boat elevator, and the wafer boat 3 and the lid 7 are raised and lowered as a unit to be inserted into and removed from the reaction tube 1. Note that the table 6 may be fixed to the lid 7 side so that the substrates W can be processed without rotating the wafer boat 3.

[0015] The plasma processing apparatus also has a gas supply unit that supplies predetermined gases such as a processing gas and a purge gas into the reaction tube 1 .

[0016] The gas supply unit includes a gas supply pipe 20. The gas supply pipe 20 is made of, for example, quartz, penetrates the sidewall of the reaction tube 1 inward, bends upward, and extends vertically. A plurality of gas holes 20g are formed at predetermined intervals in the vertical portion of the gas supply pipe 20 over a length corresponding to the wafer support range of the wafer boat 3. Each gas hole 20g discharges gas horizontally. A process gas is supplied to the gas supply pipe 20 from a gas supply source (not shown) via a gas pipe. A flow rate controller (not shown) and an on-off valve (not shown) are provided in the gas pipe. Thus, the process gas from the gas supply source is supplied into the reaction tube 1 via the gas pipe and the gas supply pipe 20. The flow rate controller is configured to control the flow rate of the gas supplied from the gas supply pipe 20 into the reaction tube 1. The on-off valve is configured to control the supply and stop of the gas supplied from the gas supply pipe 20 into the reaction tube 1.

[0017] 3, four gas supply pipes 20 are shown, but the number of gas supply pipes 20 is not limited to this. Furthermore, the four gas supply pipes 20 may be configured to supply different gases into the reaction tube 1, or at least two or more gas supply pipes 20 may be configured to supply the same gas into the reaction tube 1.

[0018] A pair of electrodes 31A and 31B are provided on the outside of the reaction tube 1. The pair of electrodes 31A and 31B are formed of flat plates and are provided on electrode installation parts 1a and 1b provided on the outside of the reaction tube 1. The pair of electrodes 31A and 31B are arranged opposite to the center of the reaction tube 1 (the center of the substrates W supported by the wafer boat 3). That is, the electrodes 31A and 31B are arranged at positions rotated 180° in the circumferential direction of the reaction tube 1. The pair of electrodes 31A and 31B are arranged parallel to each other. The electrode installation parts 1a and 1b may be formed integrally with the reaction tube 1 or may be formed separately.

[0019] The electrodes 31A, 31B are made of a good conductor such as a metal. Preferably, the electrodes 31A, 31B are made of a nickel alloy. By using a nickel alloy as the material for the electrodes 31A, 31B, the influence of metal contamination on the reaction tube 1 (diffusion of metal atoms into the reaction tube 1 made of quartz) can be suppressed compared to when copper is used as the material for the electrodes 31A, 31B. Furthermore, the nickel alloy has high heat resistance, allowing it to be used within the usable temperature range of the plasma processing apparatus (the temperature to which it is heated by the heating mechanism 50 described later, for example, a range from room temperature to 900°C). Furthermore, the nickel alloy has oxidation resistance.

[0020] Each of the electrodes 31A and 31B is connected to a high-frequency power supply 33 via an impedance matching box 32. The high-frequency power supply 33 and the impedance matching box 32 constitute a high-frequency control system. The high-frequency control system applies impedance-matched high-frequency power to each of the electrodes 31A and 31B. The high-frequency power applied from the impedance matching box 32 to the electrodes 31A and 31B has, for example, opposite-phase voltages (a phase difference of 180°) and the same voltage amplitude and frequency. In other words, the matching circuit of the impedance matching box 32 is determined so that the voltages are opposite-phase (a phase difference of 180°) and the same voltage amplitude and frequency. This allows a high Vpp (maximum amplitude difference between the electrode voltages) to be obtained with low power. Note that, although FIGS. 1 and 2 illustrate the case where high-frequency power is supplied to each of the electrodes 31A and 31B from a single set of the impedance matching box 32 and the high-frequency power supply 33, this configuration is not limiting. The impedance matching device 32 and the high-frequency power supply 33 that supply high-frequency power to the electrode 31A may be separately provided from the impedance matching device 32 and the high-frequency power supply 33 that supply high-frequency power to the electrode 31B. Alternatively, the pair of electrodes 31A, 31B may be configured such that high-frequency power is supplied to one electrode 31A from the high-frequency power supply 33 via the impedance matching device 32, and the other electrode 31B is grounded.

[0021] The power supply lines of the electrodes 31A and 31B are preferably connected to the centers of the electrodes, so that high frequency power is applied to the centers of the electrodes 31A and 31B.

[0022] The frequency of the high frequency power applied to the electrodes 31A and 31B can be in the range of 1 kHz to 100 MHz. In addition, the frequency of the high frequency power applied to the electrodes 31A and 31B is preferably 40 MHz or less to prevent the wavelength of the voltage standing wave generated on the electrodes from affecting the film formation process (substrate processing).

[0023] The inside of the reaction tube 1 is evacuated by an exhaust device 42 (described later) and is reduced in pressure (vacuum atmosphere). A process gas is supplied to the inside of the reaction tube 1 from a gas supply pipe 20. On the other hand, the outside of the reaction tube 1 is an atmospheric atmosphere. Electrodes 31A and 31B are disposed in the space outside the reaction tube 1, which is an atmospheric atmosphere.

[0024] By applying high frequency power from each high frequency power supply 33 to each electrode 31A, 31B, an electric field is formed in the reaction tube 1, and capacitively coupled plasma (CCP) is generated in the reaction tube 1. The plurality of substrates W in the reaction tube 1 are held by a wafer boat 3 with a space in the height direction. Furthermore, by applying high frequency power to the electrodes 31A, 31B, capacitively coupled plasma is generated in the reaction tube 1. That is, plasma is generated in the space between the substrates W. Here, the interval L between the substrates W is W is preferably 10 mm or more. This can improve the in-plane uniformity of the plasma generated in the space between the substrates W. Furthermore, taking into consideration the productivity of substrate processing by the plasma processing apparatus and the size of the reaction tube 1, the substrate interval is preferably set within the range of 15 mm to 40 mm.

[0025] 1 and 2, the electrodes 31A and 31B are arranged in a range in the height direction that is wider than the range in the height direction of the multiple substrates W placed on the wafer boat 3. In other words, the width L in the height direction of the electrodes 31A and 31B is E is wider than the height range of the multiple substrates W placed on the wafer boat 3. That is, the electrodes 31A, 31B are formed up to a position higher than the uppermost substrate W placed on the wafer boat 3, and the electrodes 31A, 31B are formed up to a position lower than the lowermost substrate W placed on the wafer boat 3.

[0026] As shown in FIG. 3, the electrode 31A is arranged such that the angle θ formed by connecting both ends of the electrode 31A in the width direction (horizontal direction) with the center of the reaction tube 1 (the center of the substrates W supported by the wafer boat 3) is 0.05°. W is in the range of 20° to 60°. Wis more preferably in the range of 25° to 40°.

[0027] The width of electrode 31B is equal to the width of electrode 31A. The pair of electrodes 31A, 31B are disposed opposite to the center of the reaction tube 1 (the center of the substrates W supported on the wafer boat 3) and are disposed parallel to each other. As a result, the direction of the electric field 300 formed by the two electrodes 31A, 31B is indicated by the arrow in Figure 3. As shown in Figure 3, a uniform electric field can be formed on the substrates W.

[0028] In addition, in relation to the heating mechanism 50 (heater wire 51) described later and the reaction tube 1, the electrodes 31A and 31B shield the reaction tube 1 from radiant heat from the heating mechanism 50 (heater wire 51). For this reason, it is preferable that the circumferential length of the reaction tube 1 shielded by the electrodes 31A and 31B is, for example, 1 / 3 or less of the entire circumference. In other words, the angle θ W It is preferable that the angle θ is 60° or less. W is preferably in the range of 25° to 60°.

[0029] An exhaust port 12 is provided in the side wall of the reaction tube 1 to evacuate the inside of the reaction tube 1. An exhaust device (exhaust unit) 42 including a pressure control valve 41 for controlling the pressure inside the reaction tube 1 and a vacuum pump is connected to the exhaust port 12, and the inside of the reaction tube 1 is evacuated via the exhaust tube by the exhaust device 42.

[0030] Furthermore, thermocouples 13 (see FIG. 3) are arranged inside the reaction tube 1 along the inner wall surface of the reaction tube 1. A plurality of thermocouples 13 are provided in the height direction. The control unit 70 detects the temperature with the thermocouples 13, and the detected temperature is used to control the temperature of the substrate W.

[0031] As shown in FIG. 3, the gas supply pipe 20 and the thermocouple 13 are arranged so as to avoid the electric field (the range of the electric field direction 300) formed by the electrodes 31A and 31B.

[0032] A cylindrical heating mechanism 50 is provided around the reaction tube 1. The heating mechanism 50 has a wound heater wire 51. The heater wire 51 is arranged to surround the reaction tube 1 and the electrodes 31A and 31B. The space between the heating mechanism 50 and the reaction tube 1 is an air atmosphere, and the electrodes 31A and 31B are arranged in this space. The heating mechanism 50 heats the reaction tube 1 and the substrate W therein. The heating mechanism 50 controls the temperature of the reaction tube 1 to a desired temperature. As a result, the substrate W in the reaction tube 1 is heated by radiant heat from the wall surface of the reaction tube 1, for example. The temperature of the reaction tube 1 heated by the heating mechanism 50 is, for example, in the range of room temperature to 900°C. In the film formation process, the temperature of the reaction tube 1 is, for example, in the range of 150°C to 600°C. In the film formation process, the temperature of the reaction tube 1 is preferably, for example, in the range of 200°C to 500°C.

[0033] In addition, a shield 60 is provided outside the heating mechanism 50. That is, the shield 60 is disposed so as to surround the reaction tube 1, the plurality of electrodes 31A, 31B, and the heating mechanism 50. The shield 60 is made of a good conductor such as a metal, and is grounded.

[0034] The plasma processing apparatus also includes a control unit 70. The control unit 70 controls the operation of each unit of the plasma processing apparatus, for example, by opening and closing valves to start and stop the supply of each gas, by controlling the gas flow rate using a flow rate controller, and by controlling exhaust using an exhaust device 42. The control unit 70 also controls the on / off of high frequency power by a high frequency power supply 33, and by controlling the temperature of the reaction tube 1 and the substrates W therein using a heating mechanism 50.

[0035] The control unit 70 may be, for example, a computer. The computer programs that control the operation of each part of the plasma processing apparatus are stored in a storage medium. The storage medium may be, for example, a flexible disk, a compact disk, a hard disk, a flash memory, a DVD, or the like.

[0036] With this configuration, the plasma processing apparatus reduces the pressure inside the reaction tube 1 using the exhaust device 42, supplies a processing gas into the reaction tube 1 through the gas supply pipe 20, and applies high-frequency power to the electrodes 31A and 31B to generate a capacitively coupled plasma (CCP) inside the reaction tube 1, thereby performing processing (film formation processing, etching processing, etc.) on the substrates W. The capacitively coupled plasma is also generated in the space 1c between the substrates W. This improves the uniformity of the radicals and activated species generated by the plasma at the center and outer periphery of the substrates W. Furthermore, it is possible to generate and supply to the substrates W at concentrations sufficient for substrate processing at the center and outer periphery of the substrates W.

[0037] As shown in FIGS. 1 to 3, in the plasma processing apparatus according to this embodiment, electrodes 31A and 31B are disposed on either side of the reaction tube 1, and plasma is generated within the reaction tube 1.

[0038] The plasma formed inside the reaction tube 1 is a capacitively coupled plasma (CCP). Therefore, the inner wall surfaces of the electrode installation portions 1a and 1b of the reaction tube 1 are damaged by the plasma. Specifically, the inner wall surfaces of the electrode installation portions 1a and 1b of the reaction tube 1 are damaged by ion sputtering, ion-assisted etching, and the like. In particular, when the gas to be converted into plasma is a gas containing hydrogen but not oxygen, large stress is generated locally at the boundary between the plasma-damaged portion and the surrounding undamaged portion.

[0039] This stress occurs at the inner edge of the plasma-damaged inner wall surface layer, which is several hundred micrometers thick, and is localized in a thickness of 100 to 200 micrometers. This large locally generated stress may damage the reaction tube 1 made of quartz, and may shorten the life of the reaction tube 1.

[0040] In contrast, in the plasma processing apparatus according to this embodiment, a reaction tube wall protection member 100 is provided in the reaction tube 1 as shown in FIG. 3. The reaction tube wall protection member 100 is arranged along the inner wall surfaces of the electrode installation parts 1a and 1b on which the electrodes 31A and 31B are provided. That is, between the pair of electrodes 31A and 31B arranged opposite to each other, one reaction tube wall protection member 100 is arranged between the substrate W and one electrode installation part 1a on which the one electrode 31A is provided, and the other reaction tube wall protection member 100 is arranged between the substrate W and the other electrode installation part 1b on which the other electrode 31B is provided. The reaction tube wall protection member 100 prevents ions from the plasma formed on the substrate from being incident on the inner wall surfaces of the electrode installation parts 1a and 1b of the reaction tube 1, thereby suppressing wear of the reaction tube 1.

[0041] The reaction tube wall protecting member 100 will be further described with reference to Figs. 4 to 6. Fig. 4 is an example of a vertical cross-sectional view of a reaction tube 1 in which the reaction tube wall protecting member 100 is arranged. Fig. 5 is an example of a front view of the reaction tube wall protecting member 100 as seen from the radially outer side of the reaction tube 1. Fig. 6 is an example of a top view of the reaction tube wall protecting member 100. In the following description, the reaction tube wall protecting member 100 provided on the electrode installation part 1a side will be described as an example, but the reaction tube wall protecting member 100 provided on the electrode installation part 1b side also has a similar configuration, and therefore, redundant description will be omitted.

[0042] The reaction tube wall protection member 100 includes a reaction tube wall protection plate 110, a protrusion 115, a base 120, and a fixing shaft 125. Among the surfaces of the reaction tube wall protection plate 110, the surface facing the center of the reaction tube 1 is referred to as the front side, and the surface facing the inner wall surface of the reaction tube 1 is referred to as the back side.

[0043] The reaction tube wall protection plate 110 is a component separate from the side wall surface of the reaction tube 1 and is made of synthetic quartz glass with an OH group concentration of 200 ppm or more. This suppresses ion sputtering and ion-assisted etching of the reaction tube wall protection plate 110, and suppresses local stress from occurring on the surface of the reaction tube wall protection plate 110, compared to a component made of, for example, high-purity electrically fused silica glass. This suppresses damage to the reaction tube wall protection plate 110 due to this stress. In other words, the frequency of replacing the reaction tube wall protection plate 110 can be reduced.

[0044] Furthermore, the reaction tube wall protective plate 110 is disposed in the space between the inner wall surface of the electrode mounting part 1a and the substrate W, and is disposed so as to cover the electrode mounting part 1a. That is, the reaction tube wall protective plate 110 is disposed so as to cover the inner wall surface (the inner wall surface side of the electrode mounting parts 1a, 1b) facing the outer wall surface (the outer wall surface side of the electrode mounting parts 1a, 1b) of the reaction tube 1 on which the pair of electrodes 31A, 31B are disposed. This prevents ions from the plasma formed on the substrate W from being incident on the inner wall surfaces of the electrode mounting parts 1a, 1b. Therefore, the inner wall surfaces of the electrode mounting parts 1a, 1b are prevented from being damaged by ion sputtering, ion-assisted etching, etc., and local stress is suppressed from occurring on the surfaces of the electrode mounting parts 1a, 1b. Furthermore, even if the reaction tube 1 is made of, for example, high-purity electrically fused silica glass, wear of the reaction tube 1 can be suppressed.

[0045] Furthermore, when the entire reaction tube 1 is made of synthetic quartz glass having an OH group concentration of 200 ppm or more, the cost of the reaction tube 1 increases in view of the difficulty of procuring and processing the material. Similarly, when the electrode installation portions 1a and 1b of the reaction tube 1 are made of synthetic quartz glass having an OH group concentration of 200 ppm or more and the other portions are made of high-purity electrically fused silica glass, the cost of the reaction tube 1 also increases.

[0046] In contrast, in the plasma processing apparatus according to this embodiment, the reaction tube wall protection plate 110 made of synthetic quartz glass with an OH group concentration of 200 ppm or more is arranged inside the reaction tube 1, so that the reaction tube 1 can be made of, for example, high-purity electrically fused silica glass. This can prevent an increase in the cost of the reaction tube 1. Furthermore, when the reaction tube 1 is replaced, the procurement time for the reaction tube 1 can be shortened.

[0047] Furthermore, during maintenance, it is only necessary to replace the reaction tube wall protection member 100 or the reaction tube wall protection plate 110, which reduces the maintenance cost and environmental load compared to replacing the entire reaction tube 1.

[0048] The shape of the reaction tube wall protection plate 110 is preferably an arc shape cut out from a cylinder, so that the arc-shaped reaction tube wall protection plate 110 can be arranged along the inner wall surface of the reaction tube 1.

[0049] The shape of the reaction tube wall protective plate 110 is not limited to this. As shown in FIGS. 3 to 6, the reaction tube wall protective plate 110 may be configured by combining plate shapes. Specifically, the reaction tube wall protective plate 110 is formed by welding a plate-shaped portion 110b to one end of a plate-shaped portion 110a in the width direction and welding a plate-shaped portion 110c to the other end of the plate-shaped portion 110a in the width direction. The plate-shaped portion 110b is bent toward the front surface side (toward the center of the reaction tube 1) with respect to the plate-shaped portion 110a, and the plate-shaped portion 110c is bent toward the front surface side (toward the center of the reaction tube 1) with respect to the plate-shaped portion 110a. By arranging the plurality of plate-shaped portions 110a to 110c in a bent state in this way, the manufacturing cost of the reaction tube wall protective plate 110 can be reduced.

[0050] Furthermore, it is preferable that the upper end of the reaction tube wall protective plate 110 (reaction tube wall protecting member 100) is formed to a position higher than the upper end of the electrode 31A in the height direction (for example, a position +20 cm). Furthermore, the lower end of the reaction tube wall protective plate 110 is formed to a position lower than the lower end of the electrode 31A in the height direction, and is further formed to a pedestal part 120 that supports the reaction tube wall protective plate 110. Furthermore, the lower end of the reaction tube wall protecting member 100 is formed to the bottom flange 1d of the reaction tube 1.

[0051] As shown in FIG. 3, the reaction tube wall protection plate 110 is preferably formed to have a width greater than the width of the electrode 31A (for example, +10 cm on each side).

[0052] Moreover, the thickness of the reaction tube wall protection plate 110 (the plate-shaped portion 110a, the plate-shaped portion 110b, and the plate-shaped portion 110c) is preferably within the range of, for example, 3 mm to 4 mm.

[0053] Furthermore, the reaction tube wall protection plate 110 has a protrusion 115 formed by welding on the back side thereof. The protrusion 115 has a height of, for example, 2 mm. Like the reaction tube wall protection plate 110, the protrusion 115 is preferably made of synthetic quartz glass having an OH group concentration of 200 ppm or more.

[0054] The protrusions 115 are formed on the rear surface of the reaction tube wall protective plate 110 near the upper end thereof, and are formed at the bent portion (welded portion) between the plate-shaped portion 110a and the plate-shaped portion 110b and at the bent portion (welded portion) between the plate-shaped portion 110a and the plate-shaped portion 110c. When the reaction tube wall protection member 100 is installed in the reaction tube 1, the protrusions 115 come into contact with the inner wall surface of the reaction tube 1 to support the upper portion of the reaction tube wall protective plate 110. As a result, a gap is formed between the inner wall surface of the reaction tube 1 and the reaction tube wall protective plate 110, as shown in FIG. 4 etc.

[0055] The pedestal 120 supports the lower end of the reaction tube wall protection plate 110 erected on the pedestal 120. A fixing shaft 125 extending radially outward is provided on the back surface of the pedestal 120. The pedestal 120 is preferably made of synthetic quartz glass having an OH group concentration of 200 ppm or more, similar to the reaction tube wall protection plate 110. The fixing shaft 125 is preferably made of synthetic quartz glass having an OH group concentration of 200 ppm or more, similar to the reaction tube wall protection plate 110. The pedestal 120 and / or the fixing shaft 125 may be made of high-purity electrically fused silica glass, similar to the reaction tube 1.

[0056] When the reaction tube wall protection member 100 is attached to the reaction tube 1, the base 120 is placed on a bottom flange 1d that is provided at the lower end of the reaction tube 1 and extends inward, and the fixing shaft 125 is inserted into the opening port 1e that is formed in the side wall of the reaction tube 1. At this time, the protrusion 115 comes into contact with the inner wall surface of the reaction tube 1. As a result, a gap is formed between the back surface of the reaction tube wall protection plate 110 and the wall surface of the reaction tube 1. The fixing shaft 125 is fixed using a bottom flange 210, a retainer 220, a nut 230, and an O-ring 240 that are provided on the outside of the reaction tube 1. The structure for fixing the reaction tube wall protection member 100 to the opening port 1e can be the same as the structure for fixing the gas supply pipe 20 to the opening port of the reaction tube 1.

[0057] FIG. 7 is a cross-sectional view showing an example of the arrangement of the reaction tube 1 and the reaction tube wall protection member 100.

[0058] As shown in Fig. 4, protrusions 115 are formed on the outer periphery of the reaction tube wall protection plate 110. The reaction tube wall protection plate 110 is disposed such that the protrusions 115 come into contact with the inner wall surface of the reaction tube 1. As a result, as shown in Fig. 7, a gap L is formed between the inner wall surface of the reaction tube 1 and the back surface of the reaction tube wall protection plate 110. C It has the following characteristics.

[0059] When the inside of the reaction tube 1 is dry-cleaned, cleaning gas is also supplied to this gap, and the inner wall surfaces of the electrode installation parts 1a and 1b of the reaction tube 1 and the outer wall surface of the reaction tube wall protection plate 110 are also cleaned.

[0060] Furthermore, when performing plasma processing on the substrate W, it is preferable that an unintended discharge (abnormal discharge) does not occur between the inner wall surface of the reaction tube 1 and the outer wall surface of the reaction tube wall protective plate 110. A gap L between the inner wall surface of the reaction tube 1 and the rear surface of the reaction tube wall protective plate 110 is set. C It is preferable that the thickness is 2 mm or less.

[0061] Figure 8 is a graph showing an example of a Paschen curve. The horizontal axis is the product pd [Torr cm] of the gas pressure p [Torr] and the distance d [cm] of the discharge space. The vertical axis is m, and the voltage at which discharge starts for each gas (discharge inception voltage, spark voltage) V B [Volts]. Here, NH3, He, Ne, Ar, H2, and N2 are shown as examples of gases.

[0062] Here, the potential of the reaction tube wall protection member 100 (reaction tube wall protection plate 110) can be considered to be approximately 0 V. In addition, the gas pressure p is set to, for example, 400 mTorr, and the distance d (spacing L C ) is 2 mm, pd = 0.08 [Torr cm] (1 × 10 -1 As shown in Figure 8, pd = 1 × 10 -1 In [Torr cm], the discharge initiation voltage of NH3 is about 4000 V. That is, when the gas pressure p is set to, for example, 400 mTorr, and the distance d of the discharge space (the gap L C When the gap L between the inner wall surface of the reaction tube 1 and the rear surface of the reaction tube wall protection plate 110 is set to 2 mm or less, the discharge initiation voltage is 4000 V or more for any of the gases NH3, He, Ne, Ar, H2, and N2. In this device, the maximum high frequency voltage applied to the electrodes 31A and 31B is set to less than 4000 V. Therefore, the gap L between the inner wall surface of the reaction tube 1 and the rear surface of the reaction tube wall protection plate 110 is set to 2 mm or less. CBy setting the distance to 2 mm or less, it is possible to prevent abnormal discharge from occurring on the back side of the reaction tube wall protective plate 110. This makes it possible to prevent the inner wall surface of the reaction tube 1 from being damaged by abnormal discharge.

[0063] The present invention is not limited to the configurations described in the above embodiments, but may be combined with other elements, etc. These aspects can be changed without departing from the spirit of the present invention, and can be appropriately determined depending on the application form. [Explanation of symbols]

[0064] W substrate 1 reaction tube 1a,1b Electrode installation part 1d bottom flange 1e Opening Port 2 Ceiling panels 3 Wafer boat (substrate holder) 4 rods 5 Heat insulation tube 6 tables 7 Lid 8 Rotation Axis 9 Magnetic fluid seal 10 Sealing material 11 Arm 12 exhaust port 20 Gas supply pipe 31,31A,31B electrode 32 Impedance matching box 33 High frequency power supply 50 Heating mechanism 51 Heater wire 60 Shield 70 Control Unit 100 Reaction tube wall protection member 110 Reaction tube wall protection plate 110a~100c Plate shaped part 115 Protrusion 120 Base 125 fixing shaft

Claims

1. A cylindrical reaction tube; a substrate holder for placing a large number of substrates in multiple stages to be inserted into and removed from the reaction tube; a pair of electrodes disposed outside the reaction tube and facing each other with respect to the center of the reaction tube; a high frequency power source that applies high frequency power to one or both of the pair of electrodes to generate plasma in the reaction tube; a pair of reaction tube wall protecting members disposed between the pair of electrodes, the pair including a first reaction tube wall protecting member disposed between one electrode and the substrate holder, and a second reaction tube wall protecting member disposed between the other electrode and the substrate holder; The pair of reaction tube wall protecting members are a plasma processing apparatus for performing plasma processing on a substrate in the reaction tube, the plasma processing apparatus having a pair of electrodes disposed so as to cover an inner wall surface of the reaction tube opposite to an outer wall surface of the reaction tube on which the pair of electrodes are disposed;

2. the pair of reaction tube wall protecting members each include a reaction tube wall protecting plate for covering an inner wall surface of the reaction tube opposite to an outer wall surface of the reaction tube on which the pair of electrodes are installed, the reaction tube wall protective plate is made of synthetic quartz glass having an OH group concentration of 200 ppm or more; The plasma processing apparatus according to claim 1 .

3. The reaction tube is made of electrically fused silica glass. The plasma processing apparatus according to claim 2 .

4. the reaction tube wall protective plate has a structure in which a plurality of plate-shaped parts are bent and connected to each other. The plasma processing apparatus according to claim 2 .

5. The reaction tube wall protective plate has an arc shape. The plasma processing apparatus according to claim 2 .

6. a protrusion portion that comes into contact with an inner wall surface of the reaction tube on a back surface side of the reaction tube wall protective plate; The plasma processing apparatus according to claim 2 .

7. a distance between a back surface of the reaction tube wall protective plate and an inner wall surface of the reaction tube is 2 mm or less; The plasma processing apparatus according to claim 6 .

8. the width of the reaction tube wall protective plate is wider than the width of the electrode; The plasma processing apparatus according to claim 2 .

9. an upper end of the reaction tube wall protective plate is formed at a position higher than an upper end of the electrode, a lower end of the reaction tube wall protective plate is formed at a position lower than a lower end of the electrode; The plasma processing apparatus according to claim 2 .

10. a substrate holder for supporting a large number of substrates in multiple stages to be inserted into and removed from the reaction tube; a pair of electrodes disposed outside the reaction tube and facing each other with respect to the center of the reaction tube; and a high-frequency power supply for applying high-frequency power to one or both of the pair of electrodes to generate plasma in the reaction tube, the reaction tube wall protection member being disposed inside the reaction tube of a plasma processing apparatus for plasma processing substrates in the reaction tube, a reaction tube wall protection plate made of synthetic quartz glass having an OH group concentration of 200 ppm or more, which protects an inner wall surface of an electrode installation portion of the reaction tube where the electrode is installed; and a base portion for supporting the reaction tube wall protective plate. Reactor tube wall protection material.

11. a protrusion portion that comes into contact with an inner wall surface of the reaction tube on a back surface side of the reaction tube wall protective plate; The reaction tube wall protecting member according to claim 10.

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