Substrate processing method and substrate processing apparatus

Abstract

This technology provides the ability to etch a silicon film at a desired substrate temperature. [Solution] A substrate processing method according to one aspect of the present disclosure comprises preparing a substrate having a silicon film on its surface, supplying chlorine gas to the substrate and etching the silicon film, wherein etching the silicon film includes accumulating the chlorine gas in a retention section before supplying it to the substrate, and irradiating the chlorine gas in the retention section with ultraviolet light to generate chlorine radicals from the chlorine gas.

Description

Technical Field

[0001] The present disclosure relates to a substrate processing method and a substrate processing apparatus.

Background Art

[0002] Patent Document 1 discloses a technique of repeatedly performing film formation and etching to deposit a silicon film in a concave portion. In the etching, a gas in which hydrogen gas is added to chlorine gas is used.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present disclosure provides a technique capable of etching a silicon film at a desired substrate temperature.

Means for Solving the Problems

[0005] A substrate processing method according to an aspect of the present disclosure includes preparing a substrate having a silicon film on a surface, and supplying chlorine gas to the substrate to etch the silicon film. Etching the silicon film includes retaining the chlorine gas before being supplied to the substrate in a retention portion, and irradiating ultraviolet light to the chlorine gas in the retention portion to generate chlorine radicals from the chlorine gas.

Effects of the Invention

[0006] According to the present disclosure, a silicon film can be etched at a desired substrate temperature.

Brief Description of the Drawings

[0007] [Figure 1]This is a cross-sectional view showing a substrate processing apparatus according to an embodiment. [Figure 2] Figure 1 is a perspective view showing the configuration inside the vacuum chamber of the substrate processing apparatus. [Figure 3] Figure 1 is a plan view showing the configuration inside the vacuum chamber of the substrate processing apparatus. [Figure 4] Figure 1 is a cross-sectional view of the vacuum chamber along the circumferential direction of the rotary table of the substrate processing apparatus. [Figure 5] This is another cross-sectional view of the substrate processing apparatus shown in Figure 1. [Figure 6] This is a cross-sectional view (1) showing an example of a plasma source. [Figure 7] This is a cross-sectional view (2) showing an example of a plasma source. [Figure 8] This is a plan view showing an example of a plasma source. [Figure 9] This is an exploded perspective view showing an example of a gas heating section. [Figure 10] This is a plan view (1) showing an example of a gas heating section. [Figure 11] This is a plan view (2) showing an example of a gas heating section. [Figure 12] This is a cross-sectional view (1) showing an example of a gas heating section. [Figure 13] This is a cross-sectional view (2) showing an example of a gas heating section. [Figure 14] This is a cross-sectional view (1) showing a substrate processing method according to an embodiment. [Figure 15] This is a cross-sectional view (2) showing the substrate processing method according to the embodiment. [Figure 16] This figure shows the measurement results of the etching rate of a silicon film. [Modes for carrying out the invention]

[0008] Hereinafter, exemplary embodiments of the present disclosure, not limited to those described herein, will be described with reference to the attached drawings. In all attached drawings, identical or corresponding members or components are denoted by the same or corresponding reference numerals, and redundant descriptions are omitted.

[0009] 〔Substrate Processing Apparatus〕 A substrate processing apparatus according to an embodiment will be described. Referring to FIGS. 1 to 3, the substrate processing apparatus includes a flat vacuum chamber 1 having a substantially circular planar shape, and a rotary table 2 provided in the vacuum chamber 1 and having a rotation center at the center of the vacuum chamber 1.

[0010] The vacuum chamber 1 has a container body 12 having a bottomed cylindrical shape, and a top plate 11 that is detachably and airtightly disposed on the upper surface of the container body 12 via a seal member 13. The seal member 13 is, for example, an O-ring.

[0011] The rotary table 2 is fixed to a cylindrical core portion 21 at the center. The core portion 21 is fixed to the upper end of a rotary shaft 22 extending in the vertical direction. The rotary shaft 22 penetrates the bottom portion 14 of the vacuum chamber 1, and the lower end is attached to a drive portion 23 that rotates the rotary shaft 22 around the vertical axis. The rotary shaft 22 and the drive portion 23 are housed in a cylindrical case body 20 having an open upper surface. The case body 20 is airtightly attached to the lower surface of the bottom portion 14 of the vacuum chamber 1 by a flange portion provided on the upper surface. Thereby, the airtight state between the atmosphere inside the case body 20 and the outside atmosphere is maintained.

[0012] On the surface portion of the rotary table 2, as shown in FIGS. 2 and 3, a circular mounting portion 24 for mounting a plurality (five in the illustrated example) of substrates W along the rotation direction (circumferential direction) is provided. The substrate W is, for example, a semiconductor wafer such as a silicon wafer. In FIG. 3, for convenience, only one mounting portion 24 is shown with the substrate W. The mounting portion 24 has an inner diameter slightly larger, for example, by 4 mm than the diameter of the substrate W, and a depth substantially equal to the thickness of the substrate W. In this case, when the substrate W is accommodated in the mounting portion 24, the surface of the substrate W and the surface of the rotary table 2 (the region where the substrate W is not mounted) are at the same height. Through holes (none of which are shown) through which, for example, three lifting pins for supporting the back surface of the substrate W and raising and lowering the substrate W penetrate are formed in the bottom surface of the mounting portion 24.

[0013] FIG. 2 and FIG. 3 are diagrams for explaining the structure inside the vacuum chamber 1. For convenience of explanation, illustration of the top plate 11 is omitted. As shown in FIGS. 2 and 3, above the rotary table 2, processing gas nozzles 31, 32, 33 and separation gas nozzles 41, 42 are arranged at intervals in the circumferential direction of the vacuum chamber 1. In the illustrated example, in the clockwise direction (direction of arrow A rotation in FIG. 3) from the transfer port 15 described later, the processing gas nozzle 33, the separation gas nozzle 41, the processing gas nozzle 31, the separation gas nozzle 42, and the processing gas nozzle 32 are arranged in this order. The processing gas nozzles 31, 32, 33 and the separation gas nozzles 41, 42 are each formed of, for example, quartz. The processing gas nozzles 31, 32, 33 and the separation gas nozzles 41, 42 are each fixed to the outer peripheral wall of the container body 12 at the gas introduction ports 31a, 32a, 33a, 41a, 42a which are the proximal ends. Thereby, the processing gas nozzles 31, 32, 33 and the separation gas nozzles 41, 42 are each introduced into the vacuum chamber 1 from the outer peripheral wall of the vacuum chamber 1 and are attached so as to extend horizontally with respect to the rotary table 2 along the radial direction of the container body 12.

[0014] A supply source GS1 filled with a source gas is connected to the processing gas nozzle 31. The processing gas nozzle 31 supplies the source gas from the supply source GS1 into the vacuum chamber 1. The flow rate of the source gas from the supply source GS1 is controlled by a flow rate controller FC1. The supply of the source gas from the supply source GS1 to the inside of the vacuum chamber 1 and the stop thereof are controlled by valves VA1 and VB1. The source gas is, for example, dichlorosilane gas. Another gas, for example, a dilution gas such as argon gas may be further connected to the processing gas nozzle 31. The processing gas nozzle 31 has a plurality of discharge holes 31h (FIG. 4) that open toward the rotary table 2 arranged at intervals of, for example, 10 mm along the length direction of the processing gas nozzle 31. The lower region of the processing gas nozzle 31 becomes an adsorption region P1 for adsorbing the source gas to the substrate W. The processing gas nozzle 31 is an example of a source gas supply unit.

[0015] A supply source GS2 filled with nitriding gas is connected to the processing gas nozzle 32. The processing gas nozzle 32 supplies nitriding gas from the supply source GS2 into the vacuum chamber 1. The flow rate of the nitriding gas from the supply source GS2 is controlled by a flow controller FC2. The supply and cessation of the nitriding gas from the supply source GS2 into the vacuum chamber 1 are controlled by valves VA2 and VB2. The nitriding gas is, for example, ammonia (NH3) gas. The processing gas nozzle 32 may also be further connected to a supply source filled with another gas, such as a diluent gas such as argon gas. The region below the processing gas nozzle 32 becomes a nitriding region P2 for nitriding the raw material gas adsorbed on the substrate W in the adsorption region P1. The processing gas nozzle 32 is an example of a nitriding gas supply unit. Above the processing gas nozzle 32, a plasma generator 80 is provided, as simplified by the dashed line in Figure 3. The plasma generator 80 will be described later.

[0016] A supply source GS3 filled with chlorine gas is connected to the processing gas nozzle 33. The processing gas nozzle 33 supplies chlorine gas from the supply source GS3 into the vacuum container 1. The flow rate of chlorine gas from the supply source GS3 is controlled by a flow controller FC3. The supply and cessation of chlorine gas from the supply source GS3 into the vacuum container 1 are controlled by valves VA3 and VB3. Another supply source filled with another gas, such as a diluent gas such as argon gas, may be further connected to the processing gas nozzle 33. The area below the processing gas nozzle 33 becomes an etching area P3 for etching the film with chlorine gas. The processing gas nozzle 33 is an example of a chlorine gas supply unit. Above the processing gas nozzle 33, a gas heating unit 90 is provided, as simplified by a dashed line in Figure 3. The gas heating unit 90 will be described later.

[0017] A supply source GS6, into which the separation gas is filled, is connected to the separation gas nozzle 41. The separation gas nozzle 41 supplies the separation gas from the supply source GS6 into the vacuum vessel 1. The flow rate of the separation gas from the supply source GS6 is controlled by a flow controller FC6. The supply and cessation of the separation gas from the supply source GS6 into the vacuum vessel 1 are controlled by valves VA6 and VB6. The separation gas is an inert gas, such as argon gas.

[0018] A supply source GS7, into which the separation gas is filled, is connected to the separation gas nozzle 42. The separation gas nozzle 42 supplies the separation gas from the supply source GS7 into the vacuum vessel 1. The flow rate of the separation gas from the supply source GS7 is controlled by a flow controller FC7. The supply and cessation of the separation gas from the supply source GS7 into the vacuum vessel 1 are controlled by valves VA7 and VB7. The separation gas is an inert gas, such as argon gas.

[0019] Referring to Figures 2 and 3, two convex portions 4 are provided inside the vacuum vessel 1. The convex portions 4, together with the separation gas nozzles 41 and 42, constitute the separation region D. For this reason, as will be described later, the convex portions 4 are attached to the underside of the top plate 11 so as to protrude toward the rotary table 2. The convex portions 4 have a fan-shaped planar form with their tops cut in an arc shape. For example, the inner arc of the convex portion 4 is connected to the projection portion 5 (described later), and the outer arc is positioned along the inner circumferential surface of the container body 12 of the vacuum vessel 1.

[0020] Figure 4 shows a cross-section of the vacuum chamber 1 along the circumferential direction of the rotary table 2. As shown in Figure 4, a convex portion 4 is attached to the underside of the top plate 11. Therefore, inside the vacuum chamber 1, there is a first ceiling surface 44, which is a flat, low ceiling surface that is the underside of the convex portion 4, and a second ceiling surface 45, which is located on both sides of the first ceiling surface 44 in the circumferential direction and is higher than the first ceiling surface 44. The first ceiling surface 44 has a fan-shaped planar shape with its top cut in an arc shape. A groove 43 extending radially is provided in the center of the convex portion 4 in the circumferential direction. A separation gas nozzle 42 is housed in the groove 43. Similarly, a groove 43 is formed in the other convex portion 4, and a separation gas nozzle 41 is housed in the groove 43. A processing gas nozzle 31 is provided in the space 481 below the second ceiling surface 45. A processing gas nozzle 32 (Figure 7) is provided in the space 482 below the second ceiling surface 45. The processing gas nozzles 31 and 32 are positioned near the substrate W, spaced apart from the second ceiling surface 45.

[0021] The separation gas nozzle 42 has multiple discharge holes 42h (see Figure 4) that open toward the rotary table 2, arranged along the length of the separation gas nozzle 42 at intervals of, for example, 10 mm. Similarly to the separation gas nozzle 42, the separation gas nozzle 41 also has multiple discharge holes (not shown) that open toward the rotary table 2, arranged along the length of the separation gas nozzle 41 at intervals of, for example, 10 mm.

[0022] The first ceiling surface 44 forms a narrow separation space H relative to the rotary table 2. When separation gas is supplied from the discharge hole 42h of the separation gas nozzle 42, the separation gas flows through the separation space H toward spaces 481 and 482. At this time, the volume of separation space H is smaller than the volume of spaces 481 and 482. Therefore, the pressure in separation space H can be made higher than the pressure in spaces 481 and 482 by the separation gas. That is, a high-pressure separation space H is formed between spaces 481 and 482. In addition, the separation gas flowing out of separation space H into spaces 481 and 482 acts as a counterflow for the raw material gas from the adsorption region P1 and the nitrided gas from the nitriding region P2. As a result, the raw material gas from the adsorption region P1 and the nitrided gas from the nitriding region P2 are separated by the separation space H. Therefore, the mixing and reaction of the raw material gas and nitrided gas inside the vacuum container 1 can be reduced.

[0023] The height h1 of the first ceiling surface 44 relative to the upper surface of the rotary table 2 is set to a height suitable for making the pressure in the separation space H higher than the pressure in spaces 481 and 482, taking into consideration the pressure inside the vacuum chamber 1 when processing the substrate, the rotation speed of the rotary table 2, the amount of separation gas supplied, etc.

[0024] A projection 5 (Figures 2 and 3) is provided on the underside of the top plate 11, surrounding the outer circumference of the core portion 21 that fixes the rotating table 2. The projection 5 is continuous with, for example, the part of the convex portion 4 on the rotation center side, and its underside is formed at the same height as the first ceiling surface 44.

[0025] Figure 1, which was referred to earlier, corresponds to a cross-sectional view along line II in Figure 3, and shows the region where the second ceiling surface 45 is provided. On the other hand, Figure 5 is a cross-sectional view showing the region where the first ceiling surface 44 is provided. As shown in Figure 5, a bent portion 46 is formed on the periphery of the fan-shaped convex portion 4 (the outer edge side of the vacuum vessel 1), bending in an L-shape so as to face the outer end surface of the rotary table 2. Similar to the convex portion 4, the bent portion 46 reduces the intrusion of the raw material gas and nitride gas from both sides of the separation region D, and reduces the mixing of the raw material gas and nitride gas. The fan-shaped convex portion 4 is provided on the top plate 11, and the top plate 11 can be removed from the container body 12. For this reason, there is a small gap between the outer circumferential surface of the bent portion 46 and the container body 12. The gap between the inner circumferential surface of the bent portion 46 and the outer end surface of the rotary table 2, and the gap between the outer circumferential surface of the bent portion 46 and the container body 12 are set to dimensions similar to, for example, the height of the first ceiling surface 44 relative to the top surface of the rotary table 2.

[0026] In the separation region D, the inner circumferential wall of the container body 12 is formed as a vertical surface close to the outer circumferential surface of the bent portion 46, as shown in Figure 5. In areas other than the separation region D, the inner wall of the container body 12 is recessed outward from the portion facing the outer end surface of the rotary table 2 to the bottom 14, as shown in Figure 1. For the sake of explanation, the recessed portion having a roughly rectangular cross-sectional shape will be referred to as the exhaust region E. Specifically, the exhaust region communicating with the adsorption region P1 will be referred to as the first exhaust region E1, and the region communicating with the nitriding region P2 will be referred to as the second exhaust region E2. At the bottom of the first exhaust region E1 and the second exhaust region E2, a first exhaust port 61 and a second exhaust port 62 are formed, respectively, as shown in Figures 1 to 3. The first exhaust port 61 and the second exhaust port 62 are connected to the vacuum pump 64 via an exhaust pipe 63, as shown in Figure 1. A pressure controller 65 is provided in the exhaust pipe 63.

[0027] A heater unit 7 is provided in the space between the rotary table 2 and the bottom 14 of the vacuum vessel 1, as shown in Figures 1 and 5. The heater unit 7 heats the substrate W on the rotary table 2 to the temperature specified in the process recipe via the rotary table 2. An annular cover member 71 is provided below the periphery of the rotary table 2 (Figure 5). The cover member 71 separates the atmosphere from the space above the rotary table 2 to the exhaust regions E1 and E2 from the atmosphere in which the heater unit 7 is located, thereby suppressing the intrusion of gas into the area below the rotary table 2. The cover member 71 comprises an inner member 71a provided so as to view the outer edge of the rotary table 2 and the outer circumference of the outer edge from below, and an outer member 71b provided between the inner member 71a and the inner wall surface of the vacuum vessel 1. The outer member 71b is provided below the bent portion 46 formed on the outer edge of the convex portion 4 in the separation region D, and close to the bent portion 46. The inner member 71a surrounds the heater unit 7 all around, below the outer edge of the rotary table 2 (and below the portion slightly outside the outer edge).

[0028] The bottom portion 14, closer to the center of rotation than the space where the heater unit 7 is located, protrudes upward to form a projection 12a, approaching the core portion 21 near the center of the lower surface of the rotary table 2. A narrow space exists between the projection 12a and the core portion 21, and the gap between the inner circumferential surface of the through-hole for the rotating shaft 22 that penetrates the bottom portion 14 and the rotating shaft 22 is also narrow. These narrow spaces communicate with the case body 20. The case body 20 is provided with a purge gas supply pipe 72 for supplying purge gas into these narrow spaces for purging. The purge gas is, for example, argon gas. The bottom portion 14 of the vacuum vessel 1 is provided with a plurality of purge gas supply pipes 73 at predetermined angular intervals in the circumferential direction below the heater unit 7 for purging the space where the heater unit 7 is located. Figure 5 shows one purge gas supply pipe 73. Between the heater unit 7 and the rotary table 2, a cover member 7a is provided to cover the area from the inner circumferential wall of the outer member 71b (the upper surface of the inner member 71a) to the upper end of the protrusion 12a in the circumferential direction, in order to prevent gas from entering the area where the heater unit 7 is installed. The cover member 7a is made of, for example, quartz.

[0029] A separation gas supply pipe 51 is connected to the center of the top plate 11 of the vacuum vessel 1. The separation gas supply pipe 51 supplies separation gas to the space 52 between the top plate 11 and the core portion 21. The separation gas supplied to space 52 is discharged towards the periphery along the surface of the substrate mounting area side of the rotary table 2 through the narrow space 50 between the protrusion 5 and the rotary table 2. Space 50 can be maintained at a higher pressure than spaces 481 and 482 by the separation gas. As a result, space 50 reduces the mixing of the raw material gas supplied to the adsorption region P1 and the nitriding gas supplied to the nitriding region P2 through the central region C. In other words, space 50 (or central region C) functions similarly to the separation space H (or separation region D).

[0030] As shown in Figures 2 and 3, a transfer port 15 is formed in the side wall of the vacuum container 1 for transferring the substrate W between the external transfer arm 10 and the rotary table 2. The transfer port 15 is opened and closed by a gate valve (not shown). The substrate W is transferred between the transfer arm 10 at a position facing the transfer port 15. Below the rotary table 2, at a location corresponding to the transfer position, a transfer lifting pin and its lifting mechanism (neither shown) are provided, which pass through the mounting section 24 and lift the substrate W from the back side.

[0031] The substrate processing apparatus includes a control unit 100. The control unit 100 is an electronic circuit such as a CPU (Central Processing Unit), FPGA (Field Programmable Gate Array), or ASIC (Application Specific Integrated Circuit). The control unit 100 performs various control operations described in this specification by executing instruction codes stored in memory or by circuit design for special applications.

[0032] [Plasma source] The plasma source 80 will be described with reference to Figures 6 to 8. Figures 6 and 7 are cross-sectional views showing an example of the plasma source 80. Figure 6 corresponds to a cross-sectional view along the radial direction of the rotary table 2, and Figure 7 corresponds to a cross-sectional view along a direction perpendicular to the radial direction of the rotary table 2. Figure 8 is a plan view showing an example of the plasma source. Some components are simplified in Figures 6 to 8.

[0033] As shown in Figure 6, the plasma source 80 comprises a frame member 81, a Faraday shielding plate 82, an insulating plate 83, and an antenna 85. The frame member 81 is made of a high-frequency transparent material. The frame member 81 has a recessed area extending from its upper surface and is fitted into an opening 11a formed in the top plate 11. The Faraday shielding plate 82 is housed within the recess of the frame member 81 and has a roughly box-like shape with an open top. The insulating plate 83 is positioned on the bottom surface of the Faraday shielding plate 82. The antenna 85 is supported above the insulating plate 83. The antenna 85 has a coil-like shape with a roughly octagonal planar shape.

[0034] The opening 11a of the top plate 11 has a plurality of stepped sections. A groove is formed around the entire circumference of one of the stepped sections. A sealing member 81a is fitted into the groove. The sealing member 81a is, for example, an O-ring. The frame member 81 has a plurality of stepped sections corresponding to the stepped sections of the opening 11a. When the frame member 81 is fitted into the opening 11a, the back surface of one of the stepped sections contacts the sealing member 81a. This maintains airtightness between the top plate 11 and the frame member 81. A pressing member 81c is provided on the outer circumference of the upper surface of the frame member 81. The pressing member 81c presses the frame member 81 downward against the top plate 11. This more reliably maintains airtightness between the top plate 11 and the frame member 81.

[0035] The lower surface of the frame member 81 faces the rotary table 2 inside the vacuum chamber 1. A projection 81b that protrudes downward (towards the rotary table 2) is provided around the entire circumference of the outer circumference of the lower surface of the frame member 81. The lower surface of the projection 81b is close to the surface of the rotary table 2. The projection 81b, the surface of the rotary table 2, and the lower surface of the frame member 81 define a space (nitriding region P2) above the rotary table 2. A processing gas nozzle 32 extends into the nitriding region P2, penetrating the projection 81b. As described above, the processing gas nozzle 32 supplies nitriding gas from the supply source GS2 into the vacuum chamber 1.

[0036] The processing gas nozzle 32 has multiple discharge holes 32h formed at predetermined intervals (e.g., 10 mm) along its longitudinal direction. The processing gas nozzle 32 discharges nitride gas from the discharge holes 32h. As shown in Figure 7, the discharge holes 32h are inclined from a direction perpendicular to the rotary table 2 toward the upstream side in the rotational direction of the rotary table 2. Therefore, the nitride gas supplied from the processing gas nozzle 32 is discharged in the opposite direction to the rotational direction of the rotary table 2, specifically toward the gap between the lower surface of the projection 81b and the surface of the rotary table 2. This prevents the separated gas from flowing into the nitrided region P2 from the space below the second ceiling surface 45, which is located upstream of the plasma source 80 along the rotational direction of the rotary table 2. As described above, the projection 81b formed along the outer circumference of the lower surface of the frame member 81 is close to the surface of the rotary table 2. Therefore, the nitride gas from the processing gas nozzle 32 can easily maintain a high pressure in the nitrided region P2. This also prevents the separated gas from flowing into the nitriding region P2.

[0037] The Faraday shielding plate 82 is made of a conductive material such as metal. The Faraday shielding plate 82 is grounded. As shown in Figure 8, a plurality of slits 82s are formed at the bottom of the Faraday shielding plate 82. Each slit 82s extends approximately perpendicular to the corresponding side of the antenna 85, which has a roughly octagonal planar shape.

[0038] As shown in Figures 7 and 8, the Faraday shielding plate 82 has support portions 82a that bend outward at two locations on its upper end. The support portions 82a are supported on the upper surface of the frame member 81, thereby supporting the Faraday shielding plate 82 in a predetermined position within the frame member 81.

[0039] The insulating plate 83 is made of, for example, quartz glass. The insulating plate 83 is slightly smaller in size than the bottom surface of the Faraday shielding plate 82 and is placed on the bottom surface of the Faraday shielding plate 82. The insulating plate 83 insulates the Faraday shielding plate 82 from the antenna 85. The insulating plate 83 allows high-frequency radio waves radiated from the antenna 85 to pass downwards.

[0040] Antenna 85 is formed by winding a hollow copper tube (pipe) in, for example, three times so that its planar shape is approximately octagonal. Cooling water can be circulated within the pipe, thereby preventing the antenna 85 from being heated to a high temperature by the high-frequency power supplied to it. An upright portion 85a is provided on the antenna 85, and a support portion 85b is attached to the upright portion 85a. The support portion 85b maintains the antenna 85 in a predetermined position within the Faraday shielding plate 82. A high-frequency power supply 87 is connected to the support portion 85b via a matching box 86. The high-frequency power supply 87 generates a high frequency having, for example, a frequency of 13.56 MHz.

[0041] In the plasma source 80 having the above configuration, when high-frequency power is supplied from the high-frequency power supply 87 to the antenna 85 via the matching box 86, an electromagnetic field is generated by the antenna 85. The electric field component of the electromagnetic field is shielded by the Faraday shielding plate 82 and therefore cannot propagate downward. On the other hand, the magnetic field component propagates to the nitriding region P2 through the multiple slits 82s of the Faraday shielding plate 82. The magnetic field component generates plasma from the nitriding gas supplied to the nitriding region P2 from the processing gas nozzle 32.

[0042] [Gas heating section] The gas heating section 90 will be described with reference to Figures 9 to 13. Figure 9 is an exploded perspective view showing an example of the gas heating section 90. Figures 10 and 11 are plan views showing an example of the gas heating section 90. Figures 10 and 11 are views of the base member 91 seen from below. In Figure 11, the internal structure of the quartz box 92 is shown, with a part of the quartz box 92 and the dispersion plate 93 omitted from the illustration. Figures 12 and 13 are cross-sectional views showing an example of the gas heating section 90. Figure 12 corresponds to a cross-sectional view along the radial direction of the rotary table 2, and Figure 13 corresponds to a cross-sectional view along a direction perpendicular to the radial direction of the rotary table 2.

[0043] The gas heating unit 90 includes a base member 91, a quartz box 92, a dispersion plate 93, a lid 94, a heater 95, a quartz window 96, and a light source 97.

[0044] The base member 91 is fitted into the opening 11b formed in the top plate 11. The opening 11b of the top plate 11 has a plurality of stepped sections. A groove is formed around the entire circumference of one of the stepped sections. A sealing member 91s is fitted into the groove. The sealing member 91s is, for example, an O-ring. The base member 91 has a plurality of stepped sections corresponding to the stepped sections of the opening 11b. When the base member 91 is fitted into the opening 11b, the back surface of one of the stepped sections is in contact with the sealing member 91s. This maintains airtightness between the top plate 11 and the base member 91. The base member 91 has a fan-shaped planar form with its top cut in an arc shape. The base member 91 has an opening 91a. The opening 91a has a rectangular planar form extending along the radial direction of the rotary table 2.

[0045] The quartz box 92 is fitted into the opening 91a of the base member 91. The quartz box 92 has a roughly box-like shape with an open top. The quartz box 92 is made of, for example, quartz. The quartz box 92 has an opening 92a on its bottom surface. The opening 92a has a rectangular planar shape that extends along the radial direction of the rotary table 2. A processing gas nozzle 33 is provided inside the quartz box 92. The processing gas nozzle 33 has a plurality of discharge holes 33m, 33n formed at predetermined intervals (for example, 10 mm) along its longitudinal direction. The plurality of discharge holes 33m, 33n discharge chlorine gas into the quartz box 92. The chlorine gas discharged into the quartz box 92 remains inside the quartz box 92. As shown in Figure 13, the discharge holes 33m open toward the rotary table 2, and the discharge holes 33n open toward the upstream side in the rotational direction of the rotary table 2. In this case, the chlorine gas discharged from the discharge holes 33m and 33n tends to accumulate inside the quartz box 92.

[0046] The dispersion plate 93 is fitted into the opening 92a of the quartz box 92. The dispersion plate 93 has a plurality of gas holes 93h on its bottom surface. The plurality of gas holes 93h may be arranged at equal intervals along the radial direction of the rotary table 2. The plurality of gas holes 93h may be arranged at equal intervals along a direction perpendicular to the radial direction of the rotary table 2. The plurality of gas holes 93h discharge chlorine gas accumulated inside the quartz box 92 toward the rotary table 2.

[0047] The lid 94 is attached to the base member 91 via a sealing member 94s in an airtight manner so as to close the opening at the top of the quartz box 92. The quartz box 92 and the lid 94 function as a retention area for chlorine gas discharged from the processing gas nozzle 33. The lid 94 has a lamp opening 94a. The lamp opening 94a has a rectangular planar shape that extends radially along the rotary table 2.

[0048] The heater 95 is located inside the quartz box 92. The heater 95 heats the chlorine gas that accumulates inside the quartz box 92. The heater 95 has a main heater 95a, an inner heater 95b, and an outer heater 95c. The main heater 95a extends along the radial direction of the turntable 2, from the center to the outer circumference of the turntable 2. The inner heater 95b is located near the center of the turntable 2. The inner heater 95b extends along the radial direction of the turntable 2. Two inner heaters 95b may be provided, spaced apart in a direction perpendicular to the radial direction of the turntable 2. The outer heater 95c is located near the outer end of the turntable 2. The outer heater 95c is located further from the center of the turntable 2 than the inner heater 95b. The outer heater 95c extends along the radial direction of the turntable 2. Two outer heaters 95c may be provided spaced apart in a direction perpendicular to the radial direction of the rotary table 2. The main heater 95a, inner heater 95b, and outer heaters 95c are, for example, rod heaters.

[0049] The quartz window 96 has a plate-like shape made of quartz. The quartz window 96 has a planar shape larger than the lamp opening 94a of the lid 94. The quartz window 96 closes the lamp opening 94a of the lid 94. The quartz window 96 is attached to the lid 94 in an airtight manner via a sealing member 96s. The sealing member 96s is, for example, an O-ring. The quartz window 96 transmits ultraviolet light irradiated from the light source 97 downwards.

[0050] The light source 97 is located above the quartz window 96. The light source 97 irradiates ultraviolet light into the quartz box 92 through the quartz window 96, heating the chlorine gas that accumulates inside the quartz box 92. The light source 97 is, for example, a UV-LED (ultraviolet LED) light source or a UV lamp (ultraviolet lamp) light source.

[0051] According to the gas heating unit 90, the chlorine gas discharged from the processing gas nozzle 33 is heated by the heater 95 while being retained inside the quartz box 92. In this case, by adjusting the set temperature of the heater 95, the temperature of the chlorine gas inside the quartz box 92 can be controlled while supplying it to the substrate on the rotary table 2.

[0052] [Substrate processing method] Referring to Figures 14 and 15, a substrate processing method according to an embodiment will be described. In the following description, the case in which a silicon film 502 formed along the surface of a recess 501 of a substrate W is etched using the substrate processing apparatus described above will be used as an example. The following substrate processing method is performed under the control of the control unit 100.

[0053] First, a gate valve (not shown) is opened, and the substrate W is transferred from the outside via the transfer opening 15 by the transfer arm 10 into the mounting section 24 of the rotary table 2. As shown in Figure 14, the substrate W has a recess 501 on its surface. A silicon film 502 is formed on the surface of the recess 501. The transfer of the substrate W is performed by raising and lowering a lifting pin (not shown) from the bottom side of the vacuum container 1 through a through hole in the bottom surface of the mounting section 24 when the mounting section 24 stops in a position facing the transfer opening 15. The transfer of the substrate W is performed by intermittently rotating the rotary table 2, and the substrate W is placed in each of the five mounting sections 24 of the rotary table 2.

[0054] Next, the gate valve is closed, and the vacuum chamber 1 is evacuated by the vacuum pump 64 to the achievable vacuum level. Then, argon gas is discharged from the separation gas nozzles 41 and 42 at a predetermined flow rate, and argon gas is also discharged from the separation gas supply pipe 51 and the purge gas supply pipes 72 and 72 at a predetermined flow rate. Accordingly, the pressure controller 65 controls the pressure inside the vacuum chamber 1 to a preset processing pressure. Next, the substrate W is heated to a first temperature by the heater unit 7 while the rotary table 2 is rotated clockwise at a predetermined rotational speed. The first temperature is, for example, 350°C to 550°C.

[0055] Next, with the substrate W maintained at a first temperature, a mixed gas of argon and chlorine is supplied from the processing gas nozzle 33. The light source 97 of the gas heating unit 90 irradiates the mixed gas of argon and chlorine, which is accumulating inside the quartz box 92, with ultraviolet light. The mixed gas of argon and chlorine is heated when irradiated with ultraviolet light. This generates chlorine radicals from the chlorine gas inside the quartz box 92. The chlorine radicals are discharged from the gas holes 93h of the dispersion plate 93 towards the substrate W. In this way, chlorine radicals can be supplied to the substrate W without using plasma. Alternatively, the heater 95 of the gas heating unit 90 may be used to heat the mixed gas of argon and chlorine accumulating inside the quartz box 92. Furthermore, the flow rate of chlorine gas discharged from the processing gas nozzle 33 into the quartz box 92 may be adjusted so that there is a difference in the amount of chlorine radicals in the depth direction within the recess 501.

[0056] Each time the rotary table 2 rotates, the substrate W passes through the etching region P3.

[0057] When the substrate W reaches the etching region P3, the silicon film 502 is exposed to chlorine radicals. The silicon film 502 is etched when exposed to chlorine radicals. Isotropic etching is more likely to occur than anisotropic etching when etching the silicon film 502 with chlorine radicals. As a result, as shown in Figure 15, the silicon film 502 is etched in a distribution where the amount of etching gradually increases from the bottom of the recess 501 towards the opening in the depth direction. In this way, the silicon film 502 can be etched by supplying chlorine radicals to the substrate W regardless of the substrate temperature. Therefore, the silicon film 502 can be etched at a desired substrate temperature.

[0058] The above example describes a case where a substrate W is used in which the silicon film 502 to be etched is pre-formed along the surface of the recess 501, but the method is not limited to this. For example, a substrate W without a silicon film 502 may be prepared, and the deposition of the silicon film 502 to be etched and the etching of the silicon film 502 may be performed consecutively in the substrate processing apparatus described above. As mentioned above, since the silicon film 502 can be etched at a desired substrate temperature, the substrate temperature when etching the silicon film 502 can be the same as the substrate temperature when forming the silicon film 502. Therefore, it becomes unnecessary to change the temperature of the substrate W, and productivity is improved.

[0059] According to the embodiment, chlorine gas is retained inside a quartz box 92 before being supplied to the substrate W, and ultraviolet light is irradiated onto the chlorine gas retained inside the quartz box 92. When ultraviolet light is irradiated onto the chlorine gas, it is heated. As a result, chlorine radicals are generated from the chlorine gas inside the quartz box 92 and discharged from the gas holes 93h of the dispersion plate 93 toward the substrate W. The silicon film 502 formed on the substrate W is etched when exposed to chlorine radicals. In etching of the silicon film 502 by chlorine radicals, isotropic etching is more likely to occur than anisotropic etching. Therefore, the silicon film 502 is etched in a distribution in which the amount of etching gradually increases from the bottom in the depth direction of the recess 501 toward the opening. In this way, chlorine radicals can be supplied to the substrate W and the silicon film 502 can be etched regardless of the temperature of the substrate W (temperature of the heater unit 7). Therefore, the silicon film 502 can be etched at a desired substrate temperature.

[0060] According to this embodiment, the silicon film 502 may be etched without using plasma. In this case, damage to the components constituting the substrate processing apparatus is minimal. Therefore, particle generation can be reduced.

[0061] According to one embodiment, the chlorine gas may be heated by a heater 95 provided inside the quartz box 92. In this case, the etching rate of the silicon film 502 can be adjusted.

[0062] According to one embodiment, the chlorine gas may be heated by a plurality of heaters 95 (main heater 95a, inner heater 95b, and outer heater 95c) located at different positions inside the quartz box 92. In this case, the distribution of chlorine radicals generated inside the quartz box 92 can be adjusted.

[0063] According to one embodiment, the flow rate of chlorine gas discharged from the processing gas nozzle 33 into the quartz box 92 may be adjusted so that there is a difference in the amount of chlorine radicals in the depth direction within the recess 501. In this case, the etching shape in the depth direction of the recess 501 can be adjusted.

[0064] According to one embodiment, the silicon film 502 may be formed along the surface of the recess 501 using a substrate processing apparatus for etching the silicon film 502. In this case, the temperature of the substrate W when forming the silicon film 502 along the surface of the recess 501 and the temperature when etching the silicon film 502 may be the same. In this case, the formation and etching of the silicon film 502 can be carried out continuously without changing the temperature of the substrate W.

[0065] [Examples] In the example, a substrate having a silicon film on its surface was prepared, the silicon film was etched using the substrate processing method according to the embodiment, and the etching rate of the silicon film was measured. In the example, the etching rate of the silicon film was evaluated to see how it changed when the presence or absence of ultraviolet irradiation of chlorine gas by the light source 97 and the presence or absence of heating of chlorine gas by the heater 95 were changed. The conditions for the example are as follows.

[0066] <Common Conditions> • Heater unit 7 setting temperature: 350℃ • Pressure inside vacuum container 1: 2.0 Torr (267 Pa) • Rotation speed of turntable 2: 20 rpm • Type and flow rate of gas supplied from the processing gas nozzle 33 Argon gas: 4000 sccm Chlorine gas: 50 sccm

[0067] <Condition K> • Heater 95 setting temperature: 800℃ • Light source 97: Off

[0068] <Condition L> • Heater 95: Off • Light source 97: On

[0069] <Condition M> • Heater 95 setting temperature: 800℃ • Light source 97: On

[0070] <Condition X> • Heater 95: Off • Light source 97: Off

[0071] Figure 16 shows the measurement results of the etching rate of the silicon film. In Figure 16, the etching rates [Å / min] of the silicon film under conditions X, K, L, and M are shown from left to right.

[0072] As shown in Figure 16, the etching rate of the silicon film was 0.01 Å / min under condition X, 0.35 Å / min under condition K, 1.06 Å / min under condition L, and 1.42 Å / min under condition M.

[0073] It can be seen that under condition K, the etching rate of the silicon film is higher than under condition X. From this result, it can be said that the etching rate of the silicon film can be increased by heating the chlorine gas accumulated inside the quartz box 92 with the heater 95. This is thought to be because when the chlorine gas accumulated inside the quartz box 92 is heated by the heater 95, the chlorine molecules contained in the chlorine gas are activated and reactive species such as chlorine radicals are generated.

[0074] It can be seen that under condition L, the etching rate of the silicon film is higher than under condition X. From this result, it can be said that the etching rate of the silicon film can be increased by irradiating the chlorine gas accumulating inside the quartz box 92 with ultraviolet light from the light source 97. This is thought to be because when ultraviolet light is irradiated onto the chlorine gas accumulating inside the quartz box 92, the chlorine molecules contained in the chlorine gas are activated and reactive species such as chlorine radicals are generated.

[0075] It can be seen that under condition M, the etching rate of the silicon film is higher than under conditions K and L. From this result, it can be said that the etching rate of the silicon film can be particularly increased by heating the chlorine gas accumulating inside the quartz box 92 with the heater 95 while irradiating it with ultraviolet light from the light source 97.

[0076] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The above embodiments may be omitted, replaced, or modified in various ways without departing from the scope and spirit of the appended claims.

[0077] In the above embodiment, the substrate processing apparatus was described as a semi-batch type apparatus that processes substrates by moving multiple substrates placed on a rotating table inside a vacuum chamber through multiple processing areas in sequence by the rotation of the rotating table. However, this disclosure is not limited to this. For example, the substrate processing apparatus may be a single-wafer type apparatus that processes substrates one at a time. [Explanation of Symbols]

[0078] 90 Gas heating section 92 Quartz Box 94 Lid 97 Light source 502 Silicone film W board

Claims

1. Prepare a substrate having a silicon film on its surface, The process involves supplying chlorine gas to the substrate and etching the silicon film, It has, Etching the aforementioned silicon film is The chlorine gas is allowed to remain in the retention section before being supplied to the substrate, The chlorine gas in the stagnant section is irradiated with ultraviolet light to generate chlorine radicals from the chlorine gas, including, Substrate processing method.

2. The etching of the aforementioned silicon film is performed without the use of plasma. The substrate processing method according to claim 1.

3. Etching the silicon film includes heating the chlorine gas with a heater provided in the retention area. The substrate processing method according to claim 1.

4. Etching the silicon film includes heating the chlorine gas with a plurality of heaters provided at different locations within the retention area. The substrate processing method according to claim 3.

5. The aforementioned silicon film is formed along the surface of the recess, Etching the silicon film includes adjusting the flow rate of the chlorine gas so that there is a difference in the amount of chlorine radicals in the depth direction within the recess. The substrate processing method according to claim 1.

6. Preparing the substrate includes forming the silicon film on the surface of the substrate. The temperature of the substrate when etching the silicon film is the same as the temperature of the substrate when forming the silicon film. A substrate processing method according to any one of claims 1 to 5.

7. A vacuum container for housing the circuit board, A chlorine gas supply unit that supplies chlorine gas to the substrate inside the vacuum container, Control unit and Equipped with, The aforementioned chlorine gas supply unit is A retention section for retaining the chlorine gas before it is supplied to the substrate in the vacuum container, A light source that irradiates the chlorine gas with ultraviolet light within the aforementioned retention area, It has, The control unit, The substrate having a silicon film on its surface is prepared, The chlorine gas is supplied to the substrate and the silicon film is etched, It is configured to perform, Etching the aforementioned silicon film is The chlorine gas is allowed to remain in the retention section before being supplied to the substrate, The chlorine gas in the stagnant section is irradiated with ultraviolet light to generate chlorine radicals from the chlorine gas, including, Circuit board processing equipment.

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