Plasma processing device

Abstract

To provide a plasma processing device that generates plasma on a substrate to process the substrate.SOLUTION: A plasma processing device includes a processing container, a substrate holder that is inserted into the processing container and holds a number of substrates in multiple stages, a rotation shaft that can rotate the substrate holder in the processing container, a gas supply tube that supplies a processing gas into the processing container, an exhaust part that exhausts the processing container, a pair of electrodes disposed outside the processing container and disposed opposite to each other about the center of the processing container, and a high-frequency power source that applies high-frequency power to the pair of electrodes to generate capacitively coupled plasma in the processing container. The substrate holder includes a ring member that holds the substrate and surrounds the outer side of the substrate in a radial direction in plan view.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present disclosure relates to a plasma processing apparatus.

Background Art

[0002] Patent Document 1 discloses a plasma processing apparatus including a processing container, a wafer boat that holds a plurality of wafers and is inserted into and removed from the processing container, and a plasma generation unit provided along the height direction of the processing container, one side of which is opened and communicated into the processing container by recessing a part of the side wall of the processing container outward in a concave shape. Radicals generated by the plasma generation unit are discharged from the opening of the plasma generation unit toward the center of the processing container and diffuse, and flow in a laminar state between the wafers.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In one aspect, the present disclosure provides a plasma processing apparatus that generates plasma on a substrate and performs processing on the substrate.

Means for Solving the Problems

[0005] To solve the above problems, according to one aspect, there is provided a plasma processing apparatus including a processing chamber, a substrate holder inserted into the processing chamber for holding a plurality of substrates in multiple stages, a rotating shaft for rotatably holding the substrate holder within the processing chamber, a gas supply pipe for supplying a processing gas into the processing chamber, an exhaust unit for exhausting the inside of the processing chamber, a pair of electrodes disposed outside the processing chamber and facing the center of the processing chamber, and a high-frequency power supply for applying high-frequency power to the pair of electrodes to generate capacitively coupled plasma in the processing chamber. The substrate holder holds the substrate and has a ring member that surrounds the outer side in the radial direction of the substrate in a plan view.

Advantages of the Invention

[0006] According to one aspect, it is possible to provide a plasma processing apparatus that generates plasma on a substrate and performs processing on the substrate.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Mode for Carrying Out the Invention

[0008] Hereinafter, modes for carrying out the present disclosure will be described with reference to the drawings. In each drawing, the same reference numerals are assigned to the same components, and redundant descriptions may be omitted.

[0009] 〔Plasma Processing Apparatus〕 The plasma processing apparatus (substrate processing apparatus) according to the present embodiment will be described with reference to FIGS. 1 to 3. FIG. 1 is a longitudinal sectional configuration diagram showing an example of the plasma processing apparatus. FIG. 2 is a view taken along arrow A shown in FIG. 1 and is a longitudinal sectional configuration diagram showing an example of the plasma processing apparatus. FIG. 3 is a transverse sectional configuration diagram showing an example of the plasma processing apparatus in the B-B section shown in FIG. 2. The plasma processing apparatus shown in FIGS. 1 to 3 is a batch-type plasma processing apparatus that performs substrate processing (for example, film formation processing, etc.) on a plurality of substrates W.

[0010] The plasma processing apparatus has a processing container 1 in the shape of a cylindrical body with a ceiling and an open lower end. The entire processing container 1 is formed of, for example, quartz. Near the upper end inside the processing container 1, a ceiling plate 2 formed of quartz is provided, and the region below the ceiling plate 2 is sealed.

[0011] The lower part of the processing container 1 is open, and a wafer boat (substrate holder) 3 on which a large number (for example, several to about 100) of semiconductor wafers (hereinafter referred to as "substrate W") are placed in multiple stages as substrates to be processed is inserted into the processing container 1 from below. In this way, inside the processing container 1, there is a space L along the vertical direction WA space 1c is provided, and a large number of substrates W are accommodated substantially horizontally. The wafer boat 3 is formed of, for example, quartz. The wafer boat 3 has four rods 4 (see FIG. 3. Only two are shown in FIGS. 1 and 2), and has a plurality of ring members 100 (100A) for holding the substrate W. When the substrate W is held by the wafer boat 3, in a plan view, the ring member 100 surrounds the outer side in the radial direction of the substrate W. A plurality of ring members 100 (100A) are arranged at predetermined intervals in the height direction and are supported by the rods 4. In FIGS. 1 and 2, the ring members 100 (100A) are omitted from the illustration. Details of the ring members 100 (100A) will be described later with reference to FIGS. 8 to 12.

[0012] The wafer boat 3 is placed on the table 6 via a heat-insulating cylinder 5 formed of quartz. The table 6 is supported on a rotating shaft 8 that penetrates a lid 7 made of metal (stainless steel) that opens and closes the opening at the lower end of the processing container 1.

[0013] A magnetic fluid seal 9 is provided in the penetrating portion of the rotating shaft 8, which hermetically seals the rotating shaft 8 and supports it rotatably. A seal member 10 for maintaining the airtightness inside the processing container 1 is provided between the peripheral portion of the lid 7 and the lower end of the processing container 1.

[0014] The rotating shaft 8 is attached to the tip of an arm 11 supported by a lifting mechanism (not shown) such as a boat elevator. The wafer boat 3 and the lid 7 move up and down integrally and are inserted into and removed from the processing container 1. Note that the table 6 may be fixed to the lid 7 side, and the substrate W may be processed without rotating the wafer boat 3.

[0015] Further, the plasma processing apparatus has a gas supply unit that supplies a predetermined gas such as a processing gas and a purge gas into the processing container 1.

[0016] The gas supply unit has a gas supply pipe 20. The gas supply pipe 20 is formed of, for example, quartz, penetrates the side wall of the processing container 1 inward, bends upward, and extends vertically. A plurality of gas holes 20g are formed at predetermined intervals over the vertical length corresponding to the wafer support range of the wafer boat 3 in the vertical portion of the gas supply pipe 20. Each gas hole 20g discharges gas in the horizontal direction. A processing gas is supplied to the gas supply pipe 20 from a gas supply source (not shown) via a gas pipe. The gas pipe is provided with a flow controller (not shown) and an on-off valve (not shown). Thereby, the processing gas from the gas supply source is supplied into the processing container 1 via the gas pipe and the gas supply pipe 20. The flow controller is configured to be able to control the flow rate of the gas supplied from the gas supply pipe 20 into the processing container 1. The on-off valve is configured to be able to control the supply and stop of the gas supplied from the gas supply pipe 20 into the processing container 1.

[0017] In addition, in FIG. 3, four gas supply pipes 20 are shown, but the number of gas supply pipes 20 is not limited to this. Also, the four gas supply pipes 20 may be configured to supply different gases into the processing container 1, or at least two or more gas supply pipes 20 may be configured to supply the same gas into the processing container 1.

[0018] A pair of electrodes 31A and 31B are provided outside the processing container 1. The pair of electrodes 31A and 31B are each formed of a flat plate and are installed in electrode installation portions 1a and 1b provided outside the processing container 1. Also, the pair of electrodes 31A and 31B are arranged to face each other with respect to the center of the processing container 1 (the center of the substrate 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 processing container 1. Also, the pair of electrodes 31A and 31B are arranged parallel to each other. Note that the electrode installation portions 1a and 1b may be formed integrally with the processing container 1 or may be formed separately.

[0019] The electrodes 31A and 31B are formed of a good conductor such as metal. Further, it is preferable to use a nickel alloy as the material of the electrodes 31A and 31B. By using a nickel alloy as the material of the electrodes 31A and 31B, the influence of metal contamination on the processing container 1 (diffusion of metal atoms into the processing container 1 formed of quartz) can be suppressed as compared with the case where copper is used as the material of the electrodes 31A and 31B. Further, the nickel alloy has high heat resistance that can be used in the usable temperature range of the plasma processing apparatus (the temperature heated by the heating mechanism 50 described later. For example, the range from room temperature to 900 ° C). Further, the nickel alloy has oxidation resistance.

[0020] Each of the electrodes 31A and 31B is connected to a high-frequency power source 33 via an impedance matcher 32. The high-frequency power source 33 and the impedance matcher 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. In FIGS. 1 and 2, although it is illustrated that high-frequency power is supplied from one set of the impedance matcher 32 and the high-frequency power source 33 to each of the electrodes 31A and 31B, the configuration is not limited to this. The impedance matcher 32 and the high-frequency power source 33 that supply high-frequency power to the electrode 31A and the impedance matcher 32 and the high-frequency power source 33 that supply high-frequency power to the electrode 31B may be provided individually.

[0021] The power supply lines of the electrodes 31A and 31B are preferably connected to the center of the electrodes. Thereby, high-frequency power is applied to the center 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. Further, the frequency of the high-frequency power applied to the electrodes 31A and 31B is preferably 40 MHz or less in order to suppress the influence of the wavelength of the voltage standing wave generated on the electrodes on the film formation process (substrate process).

[0023] The inside of the processing container 1 is evacuated by an exhaust device 42, which will be described later, and is under reduced pressure (vacuum atmosphere). Further, a processing gas is supplied from a gas supply pipe 20 to the inside of the processing container 1. On the other hand, the outside of the processing container 1 is in the atmospheric atmosphere. The electrodes 31A and 31B are arranged in the space of the atmospheric atmosphere outside the processing container 1.

[0024] By applying high-frequency power from each high-frequency power supply 33 to each of the electrodes 31A and 31B, an electric field is formed in the processing container 1, and capacitively coupled plasma (CCP) is generated in the processing container 1.

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

[0026] As shown in FIG. 3, in the width direction (horizontal direction), the angle θ formed by connecting both ends in the horizontal direction of the electrode 31A and the center of the processing container 1 (the center of the substrate W supported by the wafer boat 3) of the electrode 31A W is within the range of 20° to 60°. Also, the angle θ W is more preferably within the range of 25° to 40°.

[0027] Also, the width of the electrode 31B is equal to the width of the electrode 31A. Also, the pair of electrodes 31A and 31B are arranged to face each other with respect to the center of the processing container 1 (the center of the substrate W supported by the wafer boat 3) and are arranged parallel to each other. Thereby, the electric field direction 300 formed by the two electrodes 31A and 31B is indicated by an arrow in FIG. 3. As shown in FIG. 3, a uniform electric field can be formed on the substrate W.

[0028] Also, in the relationship between the heating mechanism 50 (heating element wire 51) described later and the processing container 1, the electrodes 31A and 31B shield the radiant heat from the heating mechanism 50 (heating element wire 51) to the processing container 1. For this reason, it is preferable that the circumferential length of the processing container 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 is preferably 60° or less. Also, considering the power density of the electrodes 31A and 31B, etc., the angle θ W is preferably in the range of 25° to 60°.

[0029] An exhaust port 12 for evacuating the inside of the processing container 1 is provided in the side wall portion of the processing container 1. An exhaust device (exhaust section) 42 including a pressure control valve 41 for controlling the pressure inside the processing container 1 and a vacuum pump or the like is connected to the exhaust port 12, and the inside of the processing container 1 is evacuated by the exhaust device 42 through an exhaust pipe.

[0030] Also, in the processing container 1, thermocouples 13 are arranged along the inner wall surface of the processing container 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 for temperature control of the substrate W.

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

[0032] A cylindrical heating mechanism 50 is provided around the processing container 1. The heating mechanism 50 has a wound heater element 51. The heater element 51 is arranged so as to surround the processing container 1 and the plurality of electrodes 31A, 31B. Note that the space between the heating mechanism 50 and the processing container 1 is in an air atmosphere, and the electrodes 31A, 31B are arranged in this space. The heating mechanism 50 heats the processing container 1 and the substrate W inside thereof. The heating mechanism 50 controls the temperature of the processing container 1 so as to reach a desired temperature. Thereby, the substrate W in the processing container 1 is heated by radiant heat or the like from the wall surface of the processing container 1. Note that the temperature of the processing container 1 heated by the heating mechanism 50 is, for example, in the range from room temperature to 900°C. Further, in the film formation process, the temperature of the processing container 1 is, for example, in the range from 150°C to 600°C. Further, in the film formation process, the temperature of the processing container 1 is preferably used in the range from 200°C to 500°C.

[0033] Further, a shield 60 is provided outside the heating mechanism 50. That is, the shield 60 is arranged so as to surround the processing container 1, the plurality of electrodes 31A, 31B, and the heating mechanism 50. The shield 60 is formed of a good conductor such as metal and is grounded.

[0034] Further, the plasma processing apparatus has a control unit 70. The control unit 70 controls the operations of the respective parts of the plasma processing apparatus, for example, the supply and stop of each gas by opening and closing an on-off valve, the control of the gas flow rate by a flow controller, and the exhaust control by an exhaust device 42. Further, the control unit 70 performs, for example, on-off control of high-frequency power by a high-frequency power supply 33, and temperature control of the processing container 1 and the substrate W inside thereof by the heating mechanism 50.

[0035] The control unit 70 may be, for example, a computer or the like. Further, the program of the computer that performs the operations of the respective parts of the plasma processing apparatus is 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 such a configuration, the plasma processing apparatus can reduce the pressure inside the processing chamber 1 by the evacuation device 42, supply a processing gas into the processing chamber 1 from the gas supply pipe 20, and apply high-frequency power to the electrodes 31A and 31B to generate capacitively coupled plasma (CCP) inside the processing chamber 1 and perform processing (film formation processing, etching processing, etc.) on the substrate W. Further, capacitively coupled plasma is also generated in the space 1c between the substrates W. Thereby, the uniformity of radicals and active species generated by the plasma can be improved at the central portion and the outer peripheral portion of the substrate W. Further, radicals and active species having a sufficient concentration for substrate processing can be generated at the central portion and the outer peripheral portion of the substrate W and supplied to the substrate W.

[0037] FIG. 4 is a graph showing an example of the high-frequency power applied to each of the electrodes 31A and 31B. In the upper graph, the horizontal axis represents time, and the vertical axis represents the voltage applied to the electrode 31A. In the lower graph, the horizontal axis represents time, and the vertical axis represents the voltage applied to the electrode 31B.

[0038] As shown in FIG. 4, the high-frequency power applied from the impedance matcher 32 to the electrodes 31A and 31B has voltages with opposite phases (phase difference of 180°) and the same voltage amplitude and frequency. In other words, the matching circuit of the impedance matcher 32 is determined so that the voltages have opposite phases (phase difference of 180°) and the same voltage amplitude and frequency. Thereby, a high Vpp (maximum amplitude difference of the electrode voltage) can be obtained with low power.

[0039] FIG. 5 is a graph showing an example of the plasma density n p in the region where the substrate is disposed between the electrodes. Here, an example of the plasma density n p (electron density) is shown when argon (Ar) plasma is generated inside the processing chamber 1 by applying 13.56 MHz high-frequency power to the electrodes 31A and 31B with no substrate W accommodated inside the processing chamber 1. The horizontal axis represents the distance from the center of the substrate W, the plus direction is the direction toward one electrode (31A), and the minus direction is the direction toward the other electrode (31B). The vertical axis represents the density n pis shown. Note that the plasma density n near the electrodes 31A and 31B p is omitted.

[0040] The solid line indicates the plasma density n at pressure 1 p is shown. The dashed line indicates the plasma density n at pressure 2 different from pressure 1 p is shown. Note that it has the magnitude relationship of "pressure 1 < pressure 2". As shown in FIG. 5, by changing the pressure, the distribution of the plasma density in the radial direction of the substrate W can be changed. In other words, by controlling the pressure, the uniformity of the plasma density n p in the radial direction of the substrate W can be improved.

[0041] Specifically, in the hydrogen plasma, it is preferable that the pressure in the processing vessel 1 is 25 Pa or less, preferably 15 Pa or less. Thereby, the uniformity of the plasma density in the radial direction of the substrate W can be improved.

[0042] Also, the heat insulation cylinder 5 and the wafer boat 3 are rotated by the rotating shaft 8. Thereby, the uniformity of the substrate processing (plasma processing) in the circumferential direction of the substrate W can be improved.

[0043] A plurality of substrates W in the processing vessel 1 are held with a space in the height direction by the wafer boat 3. Further, by applying high-frequency power to the electrodes 31A and 31B, a capacitively coupled plasma is generated in the processing vessel 1. That is, plasma is generated in the space between the substrates W. Here, the interval L W between the substrates W is preferably 10 mm or more. Thereby, the in-plane uniformity of the plasma generated in the space between the substrates W can be improved. Also, in consideration of the productivity of the substrate processing by the plasma processing apparatus and the size of the processing vessel 1, the substrate interval is preferably in the range of 15 mm to 40 mm.

[0044] In addition, when generating plasma using a gas containing hydrogen (H) such as hydrogen or ammonia as the processing gas, it is preferable to use synthetic quartz glass with an OH group concentration of 200 ppm or more at least for the materials of the electrode installation parts 1a and 1b.

[0045] Here, due to ions and active species containing hydrogen generated in the plasma of the gas containing hydrogen (H), the inner wall of the processing container 1 in the electrode installation parts 1a and 1b is sputtered and etched, and is altered to a silicon-rich surface. At the boundary between the altered inner wall part (electrode installation parts 1a and 1b) and other unaltered inner wall parts, a large stress is generated, and there is a risk that the processing container 1 may be damaged. On the other hand, by using synthetic quartz glass with an OH group concentration of 200 ppm or more at least for the electrode installation parts 1a and 1b, sputtering and etching can be suppressed, alteration to a silicon-rich surface can be suppressed, and damage to the processing container 1 due to stress can be suppressed.

[0046] In addition, since the inner wall of the processing container 1 of the electrode installation parts 1a and 1b is sputtered and etched by the plasma, by using synthetic quartz glass with an OH group concentration of 200 ppm or more for the inner wall of the processing container 1 or the entire processing container 1 in the electrode installation parts 1a and 1b, the metal contamination level derived from quartz can be relatively reduced compared to the case of using fused quartz glass made from natural quartz as a raw material.

[0047] Here, in the case of a relatively high pressure such as "Pressure 2" in FIG. 5 or depending on the type of gas used, the plasma density increases from the vicinity of the outer periphery of the substrate W to the inner wall of the processing container 1 where the electrode installation parts 1a and 1b are provided compared to the central part of the substrate W. In such a case, the film thickness uniformity of the thin film formed on the substrate W by plasma processing may deteriorate. Also, the film quality (such as the fine structure, refractive index, and etching rate of the film) may become non-uniform.

[0048] The plasma processing apparatus using the wafer boat 3C according to the reference example will be described with reference to FIGS. 6 and 7.

[0049] FIG. 6 is a graph showing an example of the ion current density n in the radial direction of the substrate in a plasma processing apparatus using the wafer boat 3C according to the reference example. i In FIG. 6, the horizontal axis represents the distance R [mm] in the direction from the center of the substrate W toward the electrode installation portion 1a (or the electrode installation portion 1b). In this example, the radius of the substrate W is 150 [mm]. The vertical axis represents the ion current density n i incident on the substrate W from the plasma. FIG. 7 is a diagram showing a region P with a high plasma density in a plasma processing apparatus using the wafer boat 3C according to the reference example.

[0050] The wafer boat 3C according to the reference example includes a plurality (four in the example of FIG. 7) of rods 4C. As shown in FIG. 7, the outer peripheral portion of the substrate W is inserted into a groove portion (not shown) provided in the rod 4C, and the groove portion (not shown) of the rod 4C holds the substrate W. In other words, a space is provided between the outer peripheral end of the substrate W and the inner wall of the processing vessel 1.

[0051] In the wafer boat 3C according to the reference example, an example of the measurement result of the ion current density n i incident on the substrate W from the plasma is shown in the graph of FIG. 6. As approaching from the substrate center to the outer peripheral end of the substrate, the ion current density n i gradually increases (see the black arrow).

[0052] In FIG. 7, the region P with a high plasma density is indicated by a broken line. The region P with a high plasma density is formed in the region from near the outer peripheral end of the substrate to the inner walls of the electrode installation portions 1a and 1b. Note that the region P with a high plasma density is a region where the ion current density n i is high. This region P with a high plasma density (the region where the ion current density n i is high) overlaps with the vicinity of the outer periphery of the substrate W.

[0053] Next, a plasma processing apparatus using the wafer boat 3 according to the present embodiment will be described with reference to FIGS. 8 to 12.

[0054] FIG. 8 is an example of a diagram showing the ring member 100 and the substrate W according to the first embodiment. FIG. 8(a) is an example of a longitudinal sectional view of the ring member 100 and the substrate W held by the ring member 100. FIG. 8(b) is an example of a plan view of the ring member 100 and the substrate W held by the ring member 100.

[0055] Here, the wafer boat 3 according to the first embodiment has a plurality (four in the example of FIG. 8) of rods 4 and a plurality of ring members 100.

[0056] The ring member 100 is a flat plate member having a circular outer periphery in plan view, and is an annular member having a circular opening 101 penetrating from the upper surface to the lower surface at the center of the circular flat plate member. Further, the ring member 100 has a circular concave portion 102 in plan view for holding (accommodating) the substrate W on the upper surface. The radius of the concave portion 102 is formed slightly larger than the radius of the substrate W. The concave portion 102 communicates with the opening 101. Further, the circular flat plate member, the circular opening 101, and the circular concave portion 102 are concentrically formed in plan view. Further, the depth of the concave portion 102 is, for example, substantially equal to the thickness of the substrate W. Thereby, when the substrate W is placed in the concave portion 102, the height of the upper surface of the substrate W and the upper surface of the ring member 100 may coincide.

[0057] Further, the ring member 100 is made of an insulating member (dielectric member). Specifically, the ring member 100 is preferably made of quartz. Further, the ring member 100 is electrically floating.

[0058] Further, the wafer boat 3 has a plurality of ring members 100 in the height direction with a predetermined interval. One substrate W is held for one ring member 100. The plurality of ring members 100 are connected by a plurality of rods 4 extending in the height direction. Further, the plurality of ring members 100 are concentrically arranged.

[0059] The distance X from the outer peripheral end of the substrate W to the outer peripheral end of the ring member 100 is preferably 10 mm or more and 80 mm or less, and more preferably 20 mm or more and 50 mm or less.

[0060] Also, a gap is formed between the upper surface of one ring member 100 and the lower surface of another ring member 100A disposed adjacent to the one ring member 100.

[0061] FIG. 9 is an example of a view showing the ring member 100A and the substrate W according to the second embodiment. FIG. 9(a) is an example of a longitudinal sectional view of the ring member 100A and the substrate W held by the ring member 100A. FIG. 9(b) is an example of a plan view of the ring member 100A and the substrate W held by the ring member 100A.

[0062] Here, the wafer boat 3 according to the second embodiment has a plurality (four in the example of FIG. 8) of rods 4 and a plurality of ring members 100A.

[0063] The ring member 100A is a flat plate member having a circular outer periphery in plan view, and has an annular portion 110 having a circular opening 111 penetrating from the upper surface to the lower surface at the center of the circular flat plate member. Further, the annular portion 110 has a circular recess 112 in plan view for holding (accommodating) the substrate W on the upper surface. The radius of the recess 112 is formed slightly larger than the radius of the substrate W. The recess 112 communicates with the opening 111. Also, the circular flat plate member, the circular opening 111, the circular recess 112, and the vertical wall portion 120 described later are formed concentrically in plan view. Further, the depth of the recess 112 is, for example, substantially equal to the thickness of the substrate W. Thereby, when the substrate W is placed in the recess 112, the upper surface of the substrate W and the upper surface of the annular portion 110 may be flush.

[0064] Also, the ring member 100 has a vertical wall portion 120 standing on the upper surface of the annular portion 110. The vertical wall portion 120 is formed in a cylindrical shape. Note that the annular portion 110 and the vertical wall portion 120 are formed such that the radii of their outer peripheral surfaces are equal and the outer peripheral surfaces coincide (see FIG. 9(a)). Note that the present invention is not limited to this, and the radius of the outer peripheral surface of the vertical wall portion 120 may be smaller than the radius of the outer peripheral surface of the annular portion 110.

[0065] Further, the radius of the inner peripheral surface of the vertical wall portion 120 is larger than the radius of the inner peripheral surface of the ring member 100 (the inner peripheral surface of the opening 111). Also, the radius of the inner peripheral surface of the vertical wall portion 120 is larger than the radius of the circumferential surface of the concave portion 112.

[0066] Also, the ring member 100A (the annular-shaped portion 110 and the vertical wall portion 120) is composed of an insulating member (dielectric member). Specifically, the ring member 100A (the annular-shaped portion 110 and the vertical wall portion 120) is preferably made of quartz. Also, the ring member 100A may have the annular-shaped portion 110 and the vertical wall portion 120 integrally formed. Further, the annular-shaped portion 110 and the vertical wall portion 120 may be formed separately and assembled to form the ring member 100A. Also, the ring member 100A is electrically floating.

[0067] Also, the wafer boat 3 has a plurality of ring members 100A in the height direction with a predetermined interval. One substrate W is held for one ring member 100A. The plurality of ring members 100A are connected by a plurality of rods 4 extending in the height direction. Also, the plurality of ring members 100 are arranged concentrically.

[0068] The distance X from the outer peripheral end of the substrate W to the outer peripheral end of the ring member 100 is preferably 10 mm or more and 80 mm or less, and more preferably 20 mm or more and 50 mm or less.

[0069] The height Z of the vertical wall portion 120 is preferably 3 mm or more and 30 mm or less. Also, the height Z of the vertical wall portion 120 is lower than the interval L of the substrates W (see FIG. 1). Thereby, a gap for transporting the substrate W is formed between the upper surface of the vertical wall portion 120 in one ring member 100A and the lower surface of the annular-shaped portion 110 in another ring member 100A arranged adjacent to the one ring member 100A. W Thereby, a gap for transporting the substrate W is formed between the upper surface of the vertical wall portion 120 in one ring member 100A and the lower surface of the annular-shaped portion 110 in another ring member 100A arranged adjacent to the one ring member 100A.

[0070] FIG. 10 is a graph showing an example of the ion current density in the substrate radial direction in a plasma processing apparatus using a wafer boat 3 according to a reference example and the present embodiment (first and second embodiments). In FIG. 10, the horizontal axis represents the distance R [mm] in the direction from the center of the substrate W toward the electrode installation portion 1a (or the electrode installation portion 1b). In this example, the radius of the substrate W is 150 [mm]. The vertical axis represents the ion current density n incident from the plasma onto the substrate W. i It is. FIG. 11 is a diagram showing a region P with a high plasma density in a plasma processing apparatus using a wafer boat 3 according to the present embodiment (first and second embodiments).

[0071] Here, in FIG. 10, “A” is the result of the ion current density in the wafer boat 3C according to the reference example (that is, the distance X = 0 [mm], the height Z = 0 [mm]). “B” is the result of the ion current density in the wafer boat 3 according to the first embodiment (that is, the distance X = X1 [mm], the height Z = 0 [mm]). “C” is the result of the ion current density in the wafer boat 3 according to the second embodiment (that is, the distance X = X1 [mm], the height Z = Z1 [mm]). “D” is the result of the ion current density in the wafer boat 3 according to the second embodiment (that is, the distance X = X1 [mm], the height Z = Z2 [mm]. However, Z1 <Z2). “E” is the result of the ion current density in the wafer boat 3 according to the second embodiment (that is, the distance X = X2 [mm], the height Z = Z2 [mm]. However, X1> X2).

[0072] In FIG. 10, when comparing “A” and “B”, compared with “A” without using the ring member, in “B” using the ring member 100, the ion current density n near the outer periphery of the substrate i is observed to decrease.

[0073] In FIG. 10, when comparing “B” and “C” in which the radial widths (distance X) of the ring members 100 and 100A are equal at the distance X1, compared with “B” without the vertical wall portion, in “C” having the vertical wall portion 120, the ion current density n near the outer periphery of the substrate i can be increased in the amount of decrease.

[0074] In FIG. 10, when comparing "C" and "D" where the radial width (distance X) of the ring member 100A is equal to the distance X1, in "D" where the height X2 of the vertical wall portion 120 is high, the reduction amount of the ion current density n near the outer periphery of the substrate i can be increased.

[0075] In FIG. 10, when comparing "D" and "E" where the radial width (distance X) of the ring member 100A is different, in "E" where the radial width (distance X) is short, the reduction amount of the ion current density n near the outer periphery of the substrate i can be increased. Further, in FIG. 10, when comparing "B" and "E", in "E" having the vertical wall portion 120 as compared with "B" having no vertical wall portion, while reducing the diameter of the ring member 100A, the reduction amount of the ion current density n i near the outer periphery of the substrate can be increased.

[0076] As described above, the ring members 100 and 100A have the effect of reducing the ion current density (plasma density) near the outer periphery of the substrate and improving the uniformity of the in-plane distribution of the plasma density on the substrate surface. In particular, the ring member 100A provided with the vertical wall portion 120 has a high effect of improving the uniformity of the in-plane distribution of the plasma density on the substrate surface.

[0077] In FIG. 11, the region P with a high plasma density in the wafer boat 3 having the ring members 100 and 100A is indicated by a broken line. When compared with the case where the ring members 100 and 100A are not used (see FIG. 7), in the case where the ring members 100 and 100A are used (see FIG. 11), the region P with a high plasma density decreases toward the sides of the electrodes 31A and 31B. Also, the region where this region P with a high plasma density overlaps with the substrate W also decreases.

[0078] Also, by using the ring member 100A having the vertical wall portion 120, the diameter of the ring member 100A can be reduced. Thereby, the diameter of the processing container 1 can also be reduced, and the plasma processing apparatus can be miniaturized.

[0079] In addition, the vertical wall portion 120 of the ring member 100A is electrically floating, and an ion sheath is generated on its surface by plasma. Then, the electric field generated between the electrodes 31A and 31B is shielded by the vertical wall portion 120 on which the ion sheath is generated. For this reason, the plasma density on the substrate W, particularly the plasma density at the center of the substrate (the central portion between the electrodes), decreases. Therefore, the height Z of the vertical wall portion 120 is 70% or less of the interval L of the substrate W W and preferably 50% or less is more preferable.

[0080] Note that the surface floating potential Vf (the sum of the presheath potential and the ion sheath potential) generated when the electrically floating substrate W and the ring members 100 and 100A are placed in the plasma is calculated by Equation (1).

[0081]

Equation

[0082] Here, k B is the Boltzmann constant, T e is the electron temperature, e is the elementary charge, M i is the mass of the cation, and m e is the mass of the electron. As shown in Equation (1), the floating potential Vf is determined by the gas species and the electron temperature of the plasma. For example, when the electron temperature is 3 [eV] in argon (Ar) plasma, the floating potential Vf is -15.5 [V].

[0083] FIG. 12 is an example of a diagram showing the ring members 100 and 150 and the substrate W according to the third embodiment. Note that FIG. 12 is an example of a longitudinal sectional view of the ring members 100 and 150 and the substrate W held by the ring member 100.

[0084] Here, the wafer boat 3 according to the third embodiment includes a plurality of rods 4, a plurality of ring members 100 (first ring members), and a plurality of ring members 150 (second ring members).

[0085] The ring member 100 is a member for placing the substrate W and has the same shape as the ring member 100 shown in FIG. 8.

[0086] The ring members 150 are respectively disposed between the adjacent ring members 100 in the height direction. The ring member 150 is a flat plate member having a circular outer periphery in plan view and is an annular member having a circular opening penetrating from the upper surface to the lower surface at the center of the circular flat plate member. The radius of the opening of the ring member 150 is formed larger than the radius of the substrate W.

[0087] Also, the ring members 100 and 150 are made of an insulating member (dielectric member). Specifically, the ring members 100 and 150 are preferably made of quartz. Also, the ring members 100 and 150 are electrically floating.

[0088] Here, let the width of the ring member 100 be X A and the width of the ring member 150 be X B . The horizontal positions of the outer peripheral ends of both ring members are the same, and the width X A ≧ the width X B . Also, the thickness T B of the ring member 150 is preferably 1 mm or more and 5 mm or less.

[0089] Here, the wafer boat 3 has an upper opening of the ring member 150 (an opening from the upper surface of the ring member 150 to the lower surface of the ring member 100) and a lower opening of the ring member 150 (an opening from the lower surface of the ring member 150 to the upper surface of the ring member 100) when viewed from one electrode 31A toward the other electrode 31B (in other words, when viewed in the horizontal direction). The upper and lower opening heights C U , C D of the ring member 150 as viewed from the electrode 31A, 31B sides are such that C U > C D . Also, the substrate W is transported using the upper opening of the ring member 150 (the opening with the opening height Cu).

[0090] For example, the transfer mechanism includes a pick (not shown) for transferring the substrate W and a lift mechanism (not shown) for raising and lowering the substrate W. First, the transfer mechanism moves the lift mechanism under the ring member 100 that holds the substrate W. Next, the transfer mechanism raises the lifting pins from the lift mechanism and lifts the substrate W from the ring member 100. As a result, the substrate W is disposed between the upper surface of the ring member 150 and the lower surface of the upper ring member 100. Next, the transfer mechanism inserts the pick between the upper surface of the ring member 150 and the lower surface of the substrate W held by the lifting pins. Next, the transfer mechanism lowers the lifting pins. As a result, the substrate W supported by the lifting pins is placed on the pick. Then, the transfer mechanism removes the pick to carry out the substrate W. Further, the transfer mechanism removes the lift mechanism in which the lifting pins are accommodated. Here, the case of carrying out the substrate W from the wafer boat 3 has been described as an example. However, when carrying the substrate W into the wafer boat 3, the above-described procedure may be performed in reverse, and the description thereof is omitted.

[0091] As described above, according to the wafer boat 3 having the ring members 100 and 150, there is an effect of reducing the ion current density (plasma density) near the outer periphery of the substrate and improving the uniformity of the in-plane distribution of the plasma density on the substrate surface. In particular, the ring member 150 is electrically floating, and an ion sheath is generated on its surface by the plasma. Then, the electric field generated between the electrodes 31A and 31B is shielded by the ring member 150 on which the ion sheath is generated. As a result, similar to the ring member 100A provided with the vertical wall portion 120 (see FIG. 9), there is a high effect of improving the uniformity of the in-plane distribution of the plasma density on the substrate surface.

[0092] Note that the configurations and the like described in the above embodiments are not limited to the configurations shown here, such as combinations with other elements. Regarding these points, it is possible to make changes without departing from the spirit of the present invention, and it can be appropriately determined according to the application form.

Explanation of Reference Numerals

[0093] W Substrate 1 Processing Chamber 2 Ceiling Plate 3 Wafer boat (substrate holder) 4 Rod 5 Heat preservation cylinder 6 Table 7 Cover 8 Rotating shaft 9 Magnetic fluid seal 10 Seal member 11 Arm 12 Exhaust port 20 Gas supply pipe 24g Gas hole 31, 31A, 31B Electrodes 32 Impedance matcher 33 High-frequency power supply 50 Heating mechanism 51 Heater element wire 60 Shield 70 Control unit 100, 100A, 150 Ring members 101, 111 Openings 102, 112 Recesses 110 Annular shape part 120 Vertical wall part

Claims

1. A processing vessel; a substrate holder that is inserted into the processing vessel and holds a number of substrates in multiple stages; a rotation shaft capable of rotating the substrate holder within the processing vessel; a gas supply pipe for supplying a processing gas into the processing vessel; an exhaust unit that exhausts the inside of the processing vessel; A pair of electrodes disposed outside the processing vessel and facing each other with respect to a center of the processing vessel; a high frequency power source that applies high frequency power to the pair of electrodes to generate capacitively coupled plasma in the processing chamber, The substrate holder includes: a ring member that holds the substrate and surrounds the radially outer side of the substrate in a plan view; Plasma processing equipment.

2. The ring member is made of an insulating material. The plasma processing apparatus according to claim 1 .

3. The ring members are arranged in a plurality of height directions. The plasma processing apparatus according to claim 2 .

4. The ring member is A ring-shaped portion for holding the substrate is provided. The plasma processing apparatus according to claim 3 .

5. The ring member is A ring-shaped portion for holding the substrate; A vertical wall portion provided on the upper surface of the annular portion. The plasma processing apparatus according to claim 3 .

6. The ring member is a plurality of first ring members for holding the substrate; and a plurality of second ring members each disposed between adjacent first ring members in a height direction. The plasma processing apparatus according to claim 3 .

7. When viewed from one electrode toward the other electrode, an opening height of an upper side of the second ring member is higher than an opening height of a lower side of the second ring member. The plasma processing apparatus according to claim 6 .

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