Wafer processing device

Abstract

A wafer processing device according to the present invention is characterized by comprising: a processing chamber 104 which is disposed inside a vacuum container and into which a processing gas is supplied; a sample table 201 that is disposed in the processing chamber and that has a cylindrical shape for supporting a wafer to be processed; a step part that surrounds, in a ring-like manner, a placing surface which is above the sample table and on which a wafer 204 is placed; a gas dispersion plate 208 that is placed on the bottom surface of the step part and has a ring shape surrounding the placing surface; a susceptor ring 205 that is placed on the upper surface of the gas dispersion plate and that surrounds the placing surface; and recessed parts 401 that extend in the vertical direction at a plurality of positions on an inner circumferential-side wall of the susceptor ring, and that have flow paths through which an inert gas flows and which are formed by a gap between the bottom surface of the gas dispersion plate and the bottom surface of the step part, a gap between an inner circumferential-side wall of the gas dispersion plate and an outer circumferential-side wall of the step part, and a gap between the inner circumferential-side wall of the susceptor ring and the outer circumferential-side wall of the step part.

Description

Wafer Processing Equipment

[0001] The present invention relates to a wafer processing apparatus that processes a film layer to be processed on a substrate-like sample, such as a semiconductor wafer, placed on the top surface of a sample stage arranged in a processing chamber inside a vacuum vessel by supplying gas toward the back surface of the outer edge of the wafer along the inner surface of a ring-shaped member arranged around the outer periphery of the top surface of the sample stage.

[0002] Japanese Patent Laid-Open Publication No. 2017-143186 (Patent Document 1) discloses an atomic layer-level etching process for a layer on a semiconductor wafer. Specifically, a process is first performed in which activated species (radicals) of a processing gas formed using plasma are supplied to and attached to the top surface of a semiconductor wafer sample, thereby generating a product layer on the surface. Subsequently, a process is performed in which electromagnetic waves having a wavelength including infrared rays are irradiated onto the wafer from lamps arranged in a ring shape surrounding the area above the wafer, thereby desorbing and volatilizing the product layer. This etching process is performed by removing the product layer, which has a thickness equivalent to that of an atomic layer.

[0003] In this technique, a wafer placed on a sample stage (stage) located in a processing chamber inside a vacuum vessel undergoes (1) a process of forming a layer of reaction products using radicals and (2) a process of removing the reaction layer by heating using irradiation of electromagnetic waves including infrared rays. In the reaction layer generation process (1), a process gas is first supplied to a radical generation space in the upper part of the processing chamber, where radicals are formed by activating the gas. The formed radical particles are then supplied to the upper surface of the wafer placed in the processing chamber through a gas inlet pipe connecting the processing chamber to the lower processing chamber, forming a reaction layer. In the reaction layer removal process (2), which is performed after (1), infrared light is irradiated from a lamp located above the wafer, vaporizing the products on the upper surface of the wafer and removing the reaction layer. These processes are alternately repeated to remove the film to be processed on the wafer surface.

[0004] On the other hand, during etching processes, reaction products are generated in various steps, some of which adhere or deposit on the wall surfaces of the processing chamber. If these deposits are dislodged from the surface inside the processing chamber and re-adhere to the wafer surface, pattern defects may occur, potentially impairing the performance of semiconductor devices manufactured from the wafer. In particular, products adhering to the sidewall surfaces of the stage adhere to the vicinity of the wafer, and are therefore likely to fly onto the wafer, which can easily reduce the processing yield.

[0005] To address these problems, chemical or physical cleaning methods are used. One such method is disclosed in Japanese Patent Laid-Open Publication No. 2022-152246 (Patent Document 2). This technology involves introducing an inert gas from the bottom of the stage and passing it upward through the gap between the susceptor ring placed on a dispersion plate and the side wall of the stage, diffusing it into the processing chamber. The gas flow prevents reaction products from getting around to the side wall and back surface of the stage, and removes any remaining foreign matter with heated gas.

[0006] JP 2017-143186 A JP 2022-152246 A

[0007] In the above-mentioned conventional technology, particles formed in the plasma or products formed during wafer processing adhere to the surface of the coating covering the outer wall surface of the stage's wafer-mounting surface, or interact with the outer edge of the coating covering the surface on which the wafer is mounted, causing localized wear and resulting in the generation of foreign matter. This is suppressed by supplying inert gas upward through a uniform gap in the circumferential direction between the susceptor ring or dispersion plate and the stage. Furthermore, the dispersion plate, which is processed at high pressure, is made of metal such as stainless steel because the inert gas flow path requires high processing precision, and the dispersion plate is positioned so that the circumferential variation in the gap between the plate and the stage is within an acceptable range in order to reduce unevenness in the supply of inert gas, and is then fixed to the stage with screws or bolts.

[0008] The dielectric susceptor ring placed above this metal dispersion plate must be positioned by an operator to minimize circumferential variation in the gap between its inner periphery and the outer wall of the stage. This can lead to human error. Furthermore, due to differences in thermal expansion, the dielectric susceptor ring is not fixed in position relative to the dispersion plate placed below, and as multiple wafers are processed, the circumferential variation in the gap between the dielectric susceptor ring and the outer wall of the stage increases.

[0009] Such eccentricity of the susceptor ring and misalignment leads to significant variations in the circumferential flow rate of the gas supplied through the gap between the susceptor ring and the stage, ultimately impeding the gas supply. Furthermore, when processing at high pressures, a deposition atmosphere tends to stagnate near the stage at the bottom of the processing chamber, leading to the deposition of particles from the processing gas on the stage surface, and the adsorbed film (especially the edges) reacts with the plasma and wears away, resulting in the generation of foreign matter. In particular, when polyimide is used as the material for the dielectric film placed on the stage top surface to electrostatically adsorb the wafer to the stage top surface, it is prone to react with halogen radicals, which are often used as a gas supplied to remove (clean) the deposited material. In such cases, the amount of deposition and wear on the stage surface increases, resulting in the generation of foreign matter from the stage, which was not considered in prior art.

[0010] As described above, in the conventional technology, the eccentricity of the susceptor ring causes the edge gas flow path to become non-uniform in the circumferential direction, resulting in problems such as localized wear of the stage surface material and deterioration of the wafer in-plane uniformity.

[0011] An object of the present invention is to provide a wafer processing apparatus that can achieve long-term stable operation of the stage and improve processing efficiency even when the susceptor ring is eccentric.

[0012] A wafer processing apparatus according to one embodiment of the present invention comprises a processing chamber disposed within a vacuum vessel and into which a processing gas is supplied; a cylindrical sample stage disposed within the processing chamber and supporting a wafer to be processed; a stepped portion that surrounds a mounting surface on top of the sample stage on which the wafer is placed in a ring shape; a ring-shaped gas distribution plate that is placed on the bottom surface of the stepped portion and surrounds the mounting surface; a susceptor ring that is placed on the upper surface of the gas distribution plate and surrounds the mounting surface; and a flow path through which an inert gas flows, the flow path being formed by a gap between the bottom surface of the gas distribution plate and the bottom surface of the stepped portion, a gap between an inner peripheral side wall of the gas distribution plate and an outer peripheral side wall of the stepped portion, and a gap between the inner peripheral side wall of the susceptor ring and the outer peripheral side wall of the stepped portion, and is characterized in that the inner peripheral side wall of the susceptor ring is provided with recesses extending in the vertical direction at multiple locations.

[0013] According to the present invention, it is possible to provide a wafer processing apparatus that can achieve long-term stable operation of the stage and improve processing efficiency.

[0014] FIG. 1 is a longitudinal sectional view schematically showing an outline of the configuration of a wafer processing apparatus according to an embodiment of the present invention; FIG. 2 is a longitudinal sectional view schematically showing an outline of the configuration of a stage gas supply mechanism used in an embodiment; FIG. 3 is a cross sectional view schematically showing the configuration of a dispersion plate provided in a stage gas introduction mechanism of an embodiment; FIG. 4 is a diagram schematically showing the relationship between a susceptor ring and slits in a dispersion plate that constitute a gas flow path provided in a stage gas introduction mechanism of Example 1; FIG. 5 is a schematic diagram showing the relationship between a modified susceptor ring and slits in a dispersion plate that constitute a gas flow path provided in a stage gas introduction mechanism of Example 1; FIG. 6 is a cross sectional view showing a sample stage substrate that constitutes a gas flow path provided in a stage gas introduction mechanism of Example 2;

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0016] An embodiment of the present invention will be described below with reference to Figures 1 to 5. Figure 1 is a vertical cross-sectional view that schematically shows the configuration of a wafer processing apparatus according to an embodiment of the present invention.

[0017] 1, a wafer processing apparatus 100 according to this embodiment includes a vacuum vessel 101, a discharge unit 102 that forms the upper part of the vacuum vessel 101 and generates plasma therein, and a processing chamber 104 that forms the lower part of the vacuum vessel and includes a sample stage 103 on which a semiconductor wafer (hereinafter referred to as a wafer) is placed. In other words, the sample stage 103 is a stage on whose upper mounting surface a semiconductor wafer to be processed is placed, and is disposed in the processing chamber 104 inside the vacuum vessel 101. The wafer processing apparatus 100 also includes an IR lamp unit 105 that heats the wafer on the sample stage 103, and an inner processing chamber passage 1030 that connects the discharge unit 102 and the processing chamber 104 and includes a dielectric dispersion plate 106 with through holes that allow radical particles generated by the plasma to pass through.

[0018] In the wafer processing apparatus 100 of this embodiment, the processing chamber 104 and the discharge unit 102 are cylindrical spaces whose central axes are coaxial or approximately coaxial. The processing chamber 104 and the discharge unit 102 disposed above it are connected by a cylindrical processing chamber passage 1030 whose central axes are similarly aligned with those of the processing chamber 104 and the discharge unit 102 or approximately coaxial, and are separated by a circular dispersion plate 106 disposed within the processing chamber passage 1030. The discharge unit 102 and the processing chamber 104 are connected through a plurality of through-holes concentrically arranged in the dispersion plate 106, and gas supplied into the discharge unit 102 is excited as described below and flows down the processing chamber passage 1030 toward the processing chamber 104, where it is supplied into the processing chamber 104 through the through-holes in the dispersion plate 106.

[0019] The discharge unit 102 is configured so that the process gas 1013 flows in to form plasma 1011, and the plasma state can be observed optically. As described above, the process gas supply path including the discharge unit 102, which supplies the process gas 1013 for processing the wafer into the process chamber 104, is disposed above the sample stage 103.

[0020] The discharge unit 102 comprises a cylindrical quartz chamber (dielectric chamber) 107 that forms the upper part of the vacuum vessel 101 and whose interior is communicated with the processing chamber 104 and depressurized, and an ICP coil 108 that is disposed outside the outer peripheral sidewall of the quartz chamber 107 and is wound multiple times with gaps around the sidewall. A high-frequency power source for plasma generation is connected to the ICP coil 108 via a matching box, and plasma 1011 is generated in the quartz chamber 107 by an ICP (Inductively Coupled Plasma) discharge method using high-frequency power supplied from the high-frequency power source. The frequency of the high-frequency power used is in the frequency band of several tens of megahertz, such as 13.56 MHz.

[0021] A top plate 1014 is installed above the discharge unit 102. A dispersion plate 106 and a shower plate are installed below the discharge unit 102, and the process gas 1013 is introduced into the vacuum chamber 101 via the dispersion plate 106 and the shower plate. As described above, the supply flow rate of the introduced process gas 1013 is adjusted by mass flow controllers installed for each gas type. The process gas 1013 may be a flammable gas, a combustion-supporting gas, a mixed gas thereof, or a mixed gas thereof diluted with an inert gas. The top plate 1014 is mounted on the quartz chamber 107 and attached to the discharge unit 102, with a sealing member such as an O-ring sandwiched between the rear surface of its outer periphery and the upper surface of the upper end of the quartz chamber 107. This provides an airtight seal between the interior of the discharge unit 102 and the exterior of the vacuum chamber 101.

[0022] An exhaust opening is provided at the bottom of the processing chamber 104 to reduce the pressure inside the vacuum vessel 101, and the vacuum vessel 101 is connected to a vacuum pump through an exhaust pipe from the opening. A pressure adjustment valve is provided on the path between the opening and the vacuum pump, and adjusts the flow rate or speed of the exhaust 1017 by increasing or decreasing the flow cross-sectional area of ​​the path or opening.

[0023] The processing chamber 104 has a sample stage 103 on which a wafer 204 is placed, at a position that coincides with the central axis of the discharge unit 102 and the processing chamber 104 or that can be considered to be approximately the same.

[0024] The IR lamp unit 105 for heating the wafer 204 is disposed above the processing chamber 104 and above the outer peripheral region of the sample stage 103. It is also disposed in a position surrounding the outer periphery of the processing chamber passage 1030. A flow path for radicals is provided in the center of the IR lamp unit 105. A dielectric dispersion plate 106 is provided in this flow path, with multiple concentric through-holes (passages) that shield ions and electrons generated by the plasma and allow neutral or radical particles of gas to pass through. The IR lamp unit 105 mainly comprises an IR lamp 1020, a reflector 1021 for reflecting IR light, and a light-transmitting window 1022 for transmitting IR light. The IR lamp 1020 for heating the wafer is disposed in the atmospheric atmosphere, and a light-transmitting window 1022 is disposed from the bottom surface of the IR lamp unit 105 to the outer peripheral wall surface of the processing chamber passage 1030, separating the reduced-pressure atmosphere in the processing chamber 104 from the atmospheric atmosphere.

[0025] The IR lamps 1020 are circular (circular) lamps. Specifically, the IR lamps 1020, which irradiate the wafer 204 with electromagnetic waves to heat it, are arranged in a ring shape above the sample stage 103 around the processing gas supply path. The light emitted from the IR lamps 1020 is primarily light ranging from visible light to infrared light (herein referred to as IR light). The IR lamps 1020 are connected to a lamp power supply that supplies power. In this embodiment, the near-infrared region from 500 nm to 3000 nm is used for wafer temperature control, and the far-infrared region above 3000 nm is used for IR absorption of the cleaning gas. This configuration allows the wafer-heating IR lamps 1020 to heat not only the wafer 204 but also the dispersion plate 106. As a result, the ion-blocking slit plate is also heated by the light used to heat the wafer, reducing the amount of radicals from the deposited film adhering to the slit plate and suppressing the generation of foreign particles caused by the formation of the deposited film.

[0026] Although not shown in the figure, the amount of power supplied to each arc-shaped portion of the IR lamps 1020 (three in the figure) located at each radius of the concentric circles is configured to be independently adjustable, making it possible to adjust the radial distribution of the heating amount of the wafer 204.

[0027] In the wafer processing apparatus 100 of this embodiment, the following steps are performed on the wafer 204. That is, first, (1) a step of forming a reaction product layer by radicals on the surface of the wafer 204, and (2) a step of irradiating the surface of the wafer 204 with electromagnetic waves including infrared rays, thereby heating the surface of the wafer 204 and removing the reaction product layer are performed.

[0028] In the reaction product layer generation process (1), first, a process gas 1013 is supplied into the discharge unit 102 and activated to generate plasma 1011. Ions and electrons are blocked from the formed plasma 1011 by the dispersion plate 106, and only radical particles or neutral particles are passed to the lower process chamber 104 and supplied to the upper surface of a wafer 204 placed in the lower process chamber 104, forming a reaction product layer. Specifically, radical particles or neutral particles of the process gas 1013 are introduced onto the wafer 204 placed on the mounting surface of the sample stage 103, forming a reaction product layer on the surface of a film layer to be processed that has been previously formed on the upper surface of the wafer 204. In the reaction product layer removal process (2), which is performed after the process (1), infrared light (electromagnetic waves) is irradiated from the IR lamp unit 105 disposed above the wafer 204, vaporizing the products on the upper surface of the wafer 204 and removing the reaction product layer. These processes are alternately repeated to remove the film to be processed on the surface of the wafer 204.

[0029] 2 is a longitudinal cross-sectional view showing a schematic outline of the configuration of the stage gas supply mechanism of the present embodiment shown in FIG. The sample stage 103 shown in this figure has a cylindrical structure coaxial with the central axis of the processing chamber 104, and includes an internal sample stage substrate 201 and a sample adsorption film 202 on its upper surface. The sample stage substrate 201 also has a ring-shaped stepped portion surrounding the outer periphery of the upper sample adsorption film 202 surface. A gas dispersion plate 208 is placed on the bottom surface of the ring-shaped stepped portion, and a susceptor ring 205 is placed on the upper surface of the gas dispersion plate 208.

[0030] The sample stage substrate 201 has a coolant flow path 216 formed therein for cooling the sample stage 103, and a coolant is circulated and supplied by a chiller 215. Furthermore, in order to fix the wafer 204 by electrostatic attraction, plate-shaped electrodes (electrodes for electrostatic attraction) 203 are embedded in the stage, each of which is connected to a DC power supply (power supply for electrostatic attraction). Furthermore, in order to efficiently cool the wafer 204, He gas can be supplied between the backside of the wafer 204 and the sample stage 103. In other words, the stage is provided with the functions of both fixing and cooling the wafer 204.

[0031] A resin sheet such as polyimide is attached to the sample adsorption film 202 to prevent scratches on the backside of the wafer 204 even when heating and cooling cycles are performed while the wafer 204 is adsorbed. A plate-shaped electrode plate 203 is embedded in the sample adsorption film 202 to fix the wafer 204 by electrostatic adsorption, and the electrode plate 203 is connected to a DC power source. A groove is provided in the sample adsorption film 202, which serves as a path for supplying He gas between the wafer 204 and the sample adsorption film 202. This allows the sample stage 103, whose temperature is controlled by the refrigerant path, and the wafer 204 to be in thermal contact through the He gas, thereby efficiently cooling the wafer 204, which has been heated by the IR lamp unit 105.

[0032] A quartz susceptor ring 205 is disposed on the outer periphery of the sample stage 103 to protect the sample stage 103 from corrosion caused by etching gas. The susceptor ring 205 is cylindrical and shares the same central axis as the sample stage. The inner diameter is designed to match the diameters of the side walls of the sample stage substrate 201 and the sample adsorption film 202, and covers the sample stage 103 except for the portion on which the wafer 204 is placed. The susceptor ring 205 is made of a light-transmitting material (e.g., quartz). In other words, the dielectric susceptor ring 205 is disposed on the sample stage 103, surrounding the periphery of the mounting surface of the sample stage 103.

[0033] A gas dispersion plate 208 is positioned on the upper surface of a ring-shaped step that surrounds the outer periphery of the surface of the sample adsorption film 202 on the upper part of the sample stage substrate 201, and a susceptor ring 205 is placed on this upper surface. The susceptor ring 205 is cylindrical and shares the same central axis as the sample stage. Its inner diameter is designed to match the diameters of the convex-shaped stage outer peripheral sidewall 209 created by the ring-shaped step of the sample stage substrate 201 and the sidewall of the sample adsorption film 202, and covers from the upper surface of the gas dispersion plate 208 to the outer peripheral sidewall surface of the sample stage substrate 201. The upper surface of the susceptor ring 205 is designed to be lower than the mounting surface of the sample stage 103 (the upper surface of the sample adsorption film 202) and is designed so that the lower surface of the wafer 204 does not come into contact with the upper surface of the susceptor ring 205. The susceptor ring 205 is made of a light-transmitting material (e.g., quartz). That is, the dielectric susceptor ring 205 is disposed on the sample stage 103 so as to surround the periphery of the mounting surface of the sample stage 103 .

[0034] A stage gas introduction mechanism 206 is provided below the susceptor ring 205 to remove foreign matter deposited on the side surface of the sample stage 103 and to prevent the intrusion of foreign matter. The stage gas introduction mechanism 206 includes a stage internal pipe 207 and a gas dispersion plate 208. The gas supplied through the stage internal pipe 207 is a non-volatile gas such as Ar (argon), or a molecular gas containing C-H, O-H, N-H, C=O, C=C, or C-O bonds (referred to here as an IR absorbing gas). Ar gas is used to prevent the intrusion of reaction products onto the side surface of the stage during processing. The IR absorbing gas can be used to heat and remove foreign matter because the molecular stretching and bending vibrations resonate with the wavelength of IR light, efficiently absorbing energy.

[0035] The IR light emitted from the IR lamp unit 105 has a wavelength in the wavelength band absorbed by the gas. For example, when the gas is carbon dioxide, the IR light is preferably in the far-infrared region. Specifically, the wavelength of the IR light is preferably 10.1 to 14.9 μm or 3.2 to 3.7 μm when the gas has a C-H bond, 2.7 to 3.1 μm when the gas has an O-H bond, and 2.9 μm when the gas has an N-H bond. Furthermore, the wavelength of the IR light is preferably 5.5 to 6.5 μm when the gas has a C=O bond, 6.1 to 6.3 μm when the gas has a C=C bond, and 7.7 to 9.6 μm when the gas has a C-O bond. An IR lamp for irradiating IR light of such wavelengths may be further provided within the IR lamp unit 105. That is, the IR lamp 1020 shown in FIG. 1 is a lamp for controlling wafer temperature that irradiates IR light in the near-infrared region (wavelength 0.4 to 3 μm), and an additional IR lamp for irradiating IR light of the above wavelength (4 μm or more) may be provided so as to be arranged outside the triple IR lamp 1020.

[0036] Eight internal stage pipes 207 are located inside the sample stage substrate 201, spaced equally apart in the circumferential direction, and are disposed directly below a ring-shaped downstream gas reservoir 212 formed on the back surface of a gas dispersion plate 208. The stage gas introduction mechanism 206 diffuses gas supplied from the eight internal stage pipes 207 of the mechanism in the circumferential direction of the sample stage 103 in the ring-shaped downstream gas reservoir 212, passes through 16 slits (inlet ports) 213 evenly spaced at 22.5° intervals, and diffuses it again in a subsequent ring-shaped upstream gas reservoir 214. The gas then passes through a minute gap 210 (up to 0.2 mm) between the inner peripheral wall of a susceptor ring 205 placed on the upper surface of the gas dispersion plate 208 and the outer peripheral stage side wall 209, and flows into the processing chamber 104 from near the back surface of the wafer 204, thereby suppressing adhesion of particles caused by the processing gas to the stage surface and consumption of an adsorbed film (particularly at the edge) due to reaction with plasma.

[0037] 3 is a cross-sectional view schematically illustrating the relationship between the configuration of the gas dispersion plate 208 provided in the stage gas introduction mechanism 206 of the present embodiment shown in FIG. 2 and the D-cut 404 of the sample stage substrate 201. This figure shows the structure of a quarter circumference (a range of a 90-degree angle around the center of the ring) of the ring-shaped gas dispersion plate 208 shown in FIG.

[0038] Gas supplied from eight internal stage pipes 207 of the stage gas introduction mechanism 206 is diffused in the circumferential direction of the sample stage 103 in a downstream gas reservoir 212, which is a ring-shaped space, passes through 16 slits (inlet ports) 213 installed at equal intervals of 22.5°, and is diffused again in a subsequent ring-shaped space, the upstream gas reservoir 214. In this way, in the stage gas introduction mechanism 206, a gas flow path (path) is formed so that the non-volatile gas or IR absorbing gas is sprayed from the outer periphery of the sample stage 103 toward the side of the central convex portion of the sample stage 103.

[0039] The gas dispersion plate 208, which is processed at high pressure, is made of a metal such as stainless steel because high processing precision is required for the inert gas flow path. To reduce unevenness in the supply of inert gas, the position of the minute gap 210 between the stage outer periphery sidewall 209 and the gas dispersion plate 208 is determined by a D-cut 301 on the gas dispersion plate 208 side and a D-cut 404 on the sample stage substrate 201 side, which have the same shape, so that the circumferential variation of the minute gap 210 is within an allowable range. The position is then fixed to the sample stage substrate 201 with screws or bolts, thereby controlling the minute gap 210 between the stage outer periphery sidewall 209 of the sample stage substrate 201 and the gas dispersion plate 208.

[0040] FIG. 4 is a diagram schematically illustrating the relationship between the recess 401 of the susceptor ring 205, which constitutes the gas flow path provided in the stage gas introduction mechanism 206 of this embodiment shown in FIG. 2, and the slit (inlet) 213 of the gas distribution plate 208.

[0041] The susceptor ring 205 is placed on the upper surface of a gas dispersion plate 208, which is bolted to a stage that forms a flow path of the stage gas introduction mechanism 206. The susceptor ring 205 and the sample stage substrate 201 have a D-shaped cut 403 on the susceptor ring 205 side and a D-shaped cut 404 on the sample stage substrate 201 side, which are provided for alignment purposes, and each of these has the same shape. Using these, the D-shaped cut 403 on the inner peripheral wall of the susceptor ring 205 is aligned with the D-shaped cut 404 on the periphery of the wafer mounting surface of the sample stage substrate 201, thereby aligning the susceptor ring 205 in the circumferential direction, and then the susceptor ring 205 is placed. After placement, the operator performs centering using a feeler gauge, thereby ensuring a uniform micro-gap 210 between the susceptor ring 205 and the sample stage substrate 201 in the circumferential direction.

[0042] Furthermore, four D-shaped protrusions 402 for preventing wafer misalignment, each having a convex shape with a D-cut on the inner periphery, are provided at equal intervals around the circumferential direction on the upper surface of the susceptor ring 205 for the purpose of supporting the peripheral edge of the wafer in the event of misalignment of the wafer 204. Furthermore, three or more equally spaced recesses 401 are arranged at equal intervals on the inner periphery of the susceptor ring 205, and are positioned directly above the midpoints of 16 slits (inlet ports) 213 of the stage gas introduction mechanism 206, which are arranged at equal intervals of 22.5° on the gas dispersion plate 208 on the bottom surface.

[0043] The metal gas dispersion plate 208 is fixed in position to the sample stage substrate 201 with screws and bolts, and the dielectric susceptor ring 205 placed above it is simply positioned by an operator so that there is little variation in the circumferential direction of the minute gap 210 between the inner peripheral wall of the susceptor ring 208 and the stage outer peripheral side wall 209; the susceptor ring 205 is not fixed in position to the gas dispersion plate 208. This can lead to human error.

[0044] Furthermore, during heat treatment, the susceptor ring 205 and gas dispersion plate 208 constituting the stage gas introduction mechanism 206 are both expected to reach approximately 200°C due to heat input, causing the quartz susceptor ring 205 to linearly expand 0.01 mm in the outer diameter direction, and the SUS gas dispersion plate 208 to linearly expand 0.5 mm in the outer diameter direction. In other words, as multiple wafers are processed, the difference in the amount of thermal expansion between the susceptor ring 205 and the gas dispersion plate 208 is expected to cause eccentricity, making the micro gap 210 non-uniform in the circumferential direction and resulting in a bias in the flow rate of the stage gas in the circumferential direction. However, even if the susceptor ring 205 becomes eccentric in the Cartesian coordinate system in the X and Y directions, or even if it locally contacts the stage outer peripheral sidewall 209, the recesses 401 provided at three or more equally spaced locations on the inner peripheral edge of the susceptor ring 205 can prevent local stagnation of the inert gas flowing from the minute gap 210 to the processing chamber 104, thereby suppressing circumferential non-uniformity of the stage gas. Figure 5 is a diagram schematically illustrating the relationship between a modified example of the recesses 401 of the susceptor ring 205 shown in Figure 4 and the slits (inlet ports) 213 of the gas dispersion plate 208. 4, recesses 401 are arranged at equal intervals on the inner peripheral edge of the susceptor ring 205 at three of the intermediate positions of the slits (inlet ports) 213 of the stage gas introduction mechanisms 206 arranged at 16 locations, whereas in Fig. 5, recesses 401 are arranged at equal intervals on the inner peripheral edge of the susceptor ring 205 at all 16 of the intermediate positions of the slits (inlet ports) 213 of the stage gas introduction mechanisms 206 arranged at 16 locations. In the modified example of Fig. 5, the effect of suppressing circumferential non-uniformity of the stage gas can be more pronounced than in the example of Fig. 4.

[0045] 6 and 7 are cross-sectional views showing modified examples of the sample stage substrate 201 that constitutes the gas flow path provided in the stage gas introduction mechanism 206 of the present embodiment shown in FIG.

[0046] 5 , three or more vertically extending recesses 601 are provided at equal circumferential intervals on the stage outer peripheral sidewall 209 of the sample stage substrate 201, which constitute the micro-gap 210 of the stage gas introduction mechanism 206. To reduce uneven supply of stage gas to the upper surface of the sample stage substrate 201, the positions are determined by the D-cut 301 on the gas dispersion plate 208 side and the D-cut 404 on the sample stage substrate 201 side, which have the same shape, and then the positions are fixed to the sample stage substrate 201 with screws or bolts, thereby managing the micro-gap 210 between the stage outer peripheral sidewall 209 of the sample stage substrate 201 and the gas dispersion plate 208. Furthermore, the recesses 601 provided on the stage outer peripheral sidewall 209 of the sample stage substrate 201 are located at the center positions of 16 slits (inlet ports) 213 for stage gas (inert gas) that are evenly spaced at 22.5° intervals on the gas dispersion plate 208. This prevents local stagnation of the stage gas flow and suppresses non-uniformity in the circumferential flow rate even if the susceptor ring 205 is eccentric in the X-direction or Y-direction of the Cartesian coordinate system. In addition, in this second embodiment, the upper surface of the inner peripheral edge of the susceptor ring 205 has a D-cut 403 for alignment, and the upper surface of the inner peripheral edge also has a smooth inner wall in the circumferential direction.

[0047] As shown in a modified example in FIG. 7 , three or more vertically extending convex portions 701 may be provided at equal circumferential intervals on the stage outer peripheral sidewall 209 of the sample stage substrate 201, which defines the micro-gap 210 of the stage gas introduction mechanism 206. The convex portions 701 are also located at positions including the middles of 16 adjacent slits (inlet ports) 213 for inert gas, which are evenly spaced at 22.5° intervals on the gas dispersion plate 208 fixed to the sample stage substrate 201 with four or more bolts at equal intervals. This prevents localized stagnation of the gas flow and suppresses circumferential flow rate nonuniformity even when the susceptor ring 205 is eccentric in the X and Y directions of the Cartesian coordinate system. In this second embodiment, the upper surface of the inner peripheral edge of the susceptor ring 205 has a D-shaped alignment cut 403 and a smooth inner peripheral wall.

[0048] The invention made by the present inventors has been specifically described above based on the embodiments thereof, but the present invention is not limited to the above-described embodiments and can be modified in various ways without departing from the spirit of the invention.

[0049] 100...wafer processing apparatus, 101...vacuum vessel, 102...discharge unit, 103...sample stage, 104...processing chamber, 105...IR lamp unit, 106...dispersion plate, 107...quartz chamber, 108...ICP coil, 201...sample stage substrate, 202...sample adsorption film, 203...electrode plate, 204...wafer, 205...susceptor ring, 206...stage gas introduction mechanism, 207...stage internal piping, 208...gas dispersion plate, 209...stage outer peripheral side wall, 210...micro gap, 212...downstream gas reservoir, 213...slit (inlet) , 214...upstream gas reservoir, 215...chiller, 216...refrigerant flow path, 301...D cut, 401...recess, 402...D-shaped protrusion to prevent wafer misalignment, 403...D cut, 404...D cut, 601...recess, 701...protrusion, 1011...plasma, 1013...processing gas, 1014...top plate, 1017...exhaust, 1020...IR lamp, 1021...reflector, 1022...light-transmitting window, 1030...passageway inside the processing chamber.

Claims

a gas dispersion plate having a ring-shaped configuration and placed on a bottom surface of the step portion and surrounding said placement surface; a susceptor ring placed on an upper surface of the gas dispersion plate and surrounding said placement surface; a flow path through which an inert gas flows, the flow path being constituted by a gap between the bottom surface of the gas dispersion plate and the bottom surface of the step portion, a gap between an inner peripheral side wall of the gas dispersion plate and an outer peripheral side wall of the step portion, and a gap between the inner peripheral side wall of the susceptor ring and the outer peripheral side wall of the step portion; and a wafer processing apparatus comprising: a processing chamber disposed within a vacuum vessel and into which a processing gas is supplied; 2. The wafer processing apparatus according to claim 1, wherein said recesses are provided at least in three locations at equal intervals along the inner circumference.

3. A wafer processing apparatus as described in claim 1, characterized in that the gap between the bottom surface of the gas distribution plate and the bottom surface of the step portion is composed of a ring-shaped downstream gas reservoir, a ring-shaped upstream gas reservoir, and a plurality of slits connecting the downstream gas reservoir and the upstream gas reservoir, and the recess is located at a midpoint of the plurality of slits in the circumferential direction.

4. A wafer processing apparatus comprising: a processing chamber disposed within a vacuum vessel and into which a processing gas is supplied; a cylindrical sample stage disposed within the processing chamber and supporting a wafer to be processed; a stepped portion surrounding in a ring shape a mounting surface on an upper portion of the sample stage on which the wafer is placed; a ring-shaped gas distribution plate placed on a bottom surface of the stepped portion and surrounding said mounting surface; a susceptor ring placed on the upper surface of the gas distribution plate and surrounding said mounting surface; and a flow path through which an inert gas flows, the flow path being constituted by a gap between the bottom surface of the gas distribution plate and the bottom surface of the stepped portion, a gap between an inner peripheral side wall of the gas distribution plate and an outer peripheral side wall of the stepped portion, and a gap between the inner peripheral side wall of the susceptor ring and the outer peripheral side wall of the stepped portion, and the outer peripheral side wall of the stepped portion is provided with recesses extending in the vertical direction at multiple locations on the outer peripheral side wall of the stepped portion.

5. The wafer processing apparatus according to claim 4, wherein said recesses are provided at least in three or more places at equal intervals along the outer periphery.

6. A wafer processing apparatus as described in claim 4, characterized in that the gap between the bottom surface of the gas distribution plate and the bottom surface of the step portion is composed of a ring-shaped downstream gas reservoir, a ring-shaped upstream gas reservoir, and a plurality of slits connecting the downstream gas reservoir and the upstream gas reservoir, and the recess is located at a midpoint of the plurality of slits in the circumferential direction.

7. A wafer processing apparatus comprising: a processing chamber disposed within a vacuum vessel and into which a processing gas is supplied; a cylindrical sample stage disposed within the processing chamber and supporting a wafer to be processed; a stepped portion surrounding in a ring shape a mounting surface on an upper portion of the sample stage on which the wafer is placed; a ring-shaped gas distribution plate placed on a bottom surface of the stepped portion and surrounding said mounting surface; a susceptor ring placed on an upper surface of the gas distribution plate and surrounding said mounting surface; and a flow path through which an inert gas flows, the flow path being constituted by a gap between the bottom surface of the gas distribution plate and the bottom surface of the stepped portion, a gap between an inner peripheral side wall of the gas distribution plate and an outer peripheral side wall of the stepped portion, and a gap between the inner peripheral side wall of the susceptor ring and the outer peripheral side wall of the stepped portion, and comprising protrusions extending in the vertical direction at multiple locations on the outer peripheral side wall of the stepped portion.

8. The wafer processing apparatus according to claim 7, wherein said protrusions are provided at least in three places at equal intervals along the outer periphery.

9. A wafer processing apparatus as described in claim 7, characterized in that the gap between the bottom surface of the gas distribution plate and the bottom surface of the step portion is composed of a ring-shaped downstream gas reservoir, a ring-shaped upstream gas reservoir, and a plurality of slits connecting the downstream gas reservoir and the upstream gas reservoir, and the convex portion is positioned at a midpoint of the plurality of slits in the circumferential direction.

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