Base and its manufacturing method

Abstract

The present invention relates to a base, which has a substrate containing a carbon material, and has a main surface for carrying a silicon wafer and another main surface opposite to the one main surface, the entire surface of the substrate is covered with a thin film containing silicon carbide, the emissivity deviation of the one main surface is within 3%, and the ratio of the average emissivity of the one main surface and the other main surface opposite to the one main surface is 1:1 to 1:0.8.

Description

Technical Field

[0001] The present invention relates to a susceptor and a method for manufacturing the same, and more particularly to a susceptor for holding a wafer in an epitaxial film forming apparatus and a method for manufacturing the same. Background Art

[0002] In an epitaxial film forming apparatus, which is one of the apparatuses for semiconductor manufacturing, a carbon composite material formed by covering a carbon material (called a carbon substrate) with silicon carbide (SiC) is used as a component, i.e., a susceptor, for holding a silicon wafer. The susceptor has a flat type, a cylindrical type, a monolithic type, etc., according to its shape, and various types can be used according to the apparatus and the processing method.

[0003] When manufacturing the above-mentioned susceptor, regardless of the type, a carbon substrate is placed in a predetermined coating furnace, and a silicon carbide (SiC) film is formed on the surface of the carbon substrate by a CVD method or the like, thereby obtaining a susceptor including a carbon composite material.

[0004] However, when a thin film of silicon carbide (SiC) is formed on the surface of a carbon substrate by a CVD method, the silicon carbide film does not adhere to the contact portion between a tool supporting the carbon substrate and the carbon substrate.

[0005] In order to solve such a problem, Patent Document 1 discloses that after the first film forming process, the carbon substrate is taken out from the primary furnace, and the position where the carbon substrate contacts the tool is changed to perform the second and subsequent film forming processes. In this way, a carbon composite material whose entire surface is covered with silicon carbide (SiC) can be obtained.

[0006] As described above, staggering the contact position and performing multiple film forming processes is an effective means for eliminating the contact marks of the tool, but once the carbon composite material is taken out of the furnace, the carbon composite material will be exposed to the air outside the furnace. Therefore, there is a problem that the surface of the silicon carbide film may be contaminated. In the case where the surface of the silicon carbide film is contaminated, if a new silicon carbide film is stacked on the contaminated layer and the carbon composite material is used as a base, it will become a cause of contamination of the silicon wafer in the epitaxial process.

[0007] Therefore, in the invention described in Patent Document 1, after the initial film formation of silicon carbide is carried out, the carbon composite material is taken out once to change the support position in order to eliminate the support marks, and the surface of the carbon composite material is purified (blowing halogen gas) to reduce surface contamination, and silicon carbide film formation is carried out again in the furnace.

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Application Publication No. 2008-174841 Summary of the invention

[0011] Technical problem that the invention aims to solve

[0012] However, in the method disclosed in Patent Document 1, the possibility of contamination does not disappear because the carbon substrate is taken out of the primary furnace. In addition, since a plurality of film-forming processes need to be performed at intervals, there is an undesirable problem of increased man-hours and costs.

[0013] Furthermore, the film thickness of silicon carbide is thinner than other parts in the area where the jig holding the carbon substrate contacts, and when the film is formed twice, the thickness is about half of other parts. Therefore, in the epitaxial film forming process, the carbon as the substrate may be exposed due to the consumption of the silicon carbide film.

[0014] In addition, the non-uniformity of the thickness of the silicon carbide film is also a major factor causing the film thickness variation in the epitaxial film forming process on the silicon wafer. When the film thickness of the silicon carbide film varies greatly, there is a problem that it is difficult to obtain a uniform epitaxial film due to different thermal conductivity.

[0015] In addition, if the silicon carbide film covering the carbon substrate is not uniform, the emissivity in the temperature range of the susceptor will vary. If the emissivity varies greatly, the temperature of the susceptor will vary, resulting in a variation in the wafer temperature and a variation in the thickness of the epitaxial film.

[0016] The present invention has been completed in view of the above situation, and its purpose is to provide a base and a manufacturing method thereof that can suppress contamination. The base includes a carbon composite material formed by covering the surface of a substrate of a carbon-containing material with a thin film of silicon carbide (SiC), which can improve the uniformity of the film thickness of the silicon carbide film formed on the substrate and suppress the deviation of thermal conductivity.

[0017] Technical solutions to the problem

[0018] The base of the present invention, which is completed to solve the above-mentioned problem, is characterized in that the base has a substrate containing a carbon material, and has a main surface for carrying a silicon wafer and another main surface opposite to the one main surface, the entire surface of the substrate is covered with a thin film containing silicon carbide, the deviation of the emissivity of the one main surface is within 3%, and the ratio of the average emissivity of the one main surface and the other main surface opposite to the one main surface is 1:1 to 1:0.8.

[0019] In addition, it is preferable that the emissivity deviation of the other main surface facing the one main surface is within 3%.

[0020] In addition, it is preferred that the ratio of the film thickness of the thin film formed on the other main surface to the film thickness of the thin film formed on the one main surface is greater than 0.7 and less than 1.2, and in the one main surface, the difference in film thickness between the center portion and the outer edge portion is less than 40% of the average value of the film thickness of the thin film formed on the one main surface, and the difference in film thickness between the maximum film thickness and the minimum film thickness at the outer edge portion of the one main surface is less than 40% of the average value of the film thickness of the thin film formed on the one main surface.

[0021] In addition, it is preferred that the film thickness of the thin film made of silicon carbide formed on the entire surface of the substrate is at least 60 μm.

[0022] According to such a configuration, the uniformity of the thin film formed on the surface of the substrate is improved, and the uniformity of heat conduction of one main surface becomes good. As a result, in the epitaxial film forming process on a silicon wafer using the susceptor, a uniform epitaxial film can be obtained.

[0023] In addition, the manufacturing method of the susceptor involved in the present invention completed to solve the above-mentioned problems is the manufacturing method of the above-mentioned susceptor, which is characterized by comprising the following steps: in a chamber, while moving the supporting position of a substrate containing carbon material, the substrate is supported, and the raw material gas is supplied in a direction parallel to the one main surface of the substrate, thereby forming a thin film containing silicon carbide on the entire surface of the substrate.

[0024] According to such a method, the susceptor in which contamination can be suppressed can be obtained.

[0025] Effects of the Invention

[0026] According to the present invention, a base capable of suppressing contamination and a method for manufacturing the same can be provided. The base comprises a carbon composite material formed by covering the surface of a substrate of a carbon-containing material with a thin film of silicon carbide (SiC), which can improve the uniformity of the film thickness of the silicon carbide film formed on the substrate and suppress deviations in thermal conductivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a cross-sectional view of the base involved in the present invention.

[0028] Figure 2 Yes Figure 1 An enlarged cross-sectional view of a portion of the base.

[0029] Figure 3 It is a schematic representation of the manufacturing Figure 1 A cross-sectional view of a CVD apparatus used when using a susceptor.

[0030] Figure 4 yes Figure 3 Top view of the CVD device.

[0031] Explanation of symbols

[0032] 1 Base

[0033] 2 Carbon substrate

[0034] 3 films

[0035] 4 Countersinking

[0036] 5 CVD device

[0037] 10 Chamber

[0038] 11 Gas inlet

[0039] 12 Gas outlet

[0040] 20 Supporting part DETAILED DESCRIPTION

[0041] The following is based on Figures 1 to 4 An embodiment of the susceptor and the method for manufacturing the susceptor according to the present invention will be described. The drawings are schematic or conceptual diagrams, and the relationship between the thickness and width of each part, the size ratio between the parts, etc. are not accurately shown.

[0042] like Figure 1 As shown, the susceptor 1 has a disk-shaped carbon substrate 2 made of a carbon material. The entire surface of the carbon substrate 2 is covered with a thin film 3 of a predetermined thickness (for example, 60 μm or more) made of silicon carbide.

[0043] That is, the film 3 is composed of a film 3F containing silicon carbide that covers a main surface F1 that serves as a chip mounting surface of the base 1, a film 3B containing silicon carbide that covers another main surface F2 that serves as the back surface opposite to the main surface F1, and a film 3S containing silicon carbide that covers the outer peripheral surface of the carbon substrate 2.

[0044] The susceptor 1 is a so-called one-piece type susceptor, and a concave countersunk portion 4 for mounting a semiconductor substrate is formed on one main surface F1 of the susceptor 1 .

[0045] The countersunk portion 4 is formed in a circular shape in a plan view, and a cylindrical recess 4a is formed in the center. In addition, the base 1 has circular symmetry with respect to the rotation axis L passing through the center O. At this time, if the depth of the deepest part (center O) of the countersunk portion 4 is set to To, the average depth Td is To / 2.

[0046] Furthermore, the ratio (T / Td) of the thickness T of the base 1 to the average depth Td is preferably 6≤T / Td≤30. The ratio (T / To) of the thickness T of the base 1 to the depth To is preferably 3≤T / To≤13.

[0047] In this way, since the countersunk portion 4 is formed so that the ratio (T / Td) of the thickness T of the base 1 to the average depth Td satisfies preferably 6≤T / Td≤30, the effect of suppressing warping can be obtained.

[0048] Here, when the ratio (T / Td) of the thickness T of the susceptor 1 to the average depth Td is less than 6, the countersink is too deep for the thickness of the susceptor 1, so the film formation on the periphery of the wafer may become poor, which is not preferred. In addition, when the ratio (T / Td) of the thickness T of the susceptor 1 to the average depth Td exceeds 30, the susceptor becomes thick, the influence of the rigidity of the carbon substrate 2 cannot be ignored, and it is difficult to control the warpage of the film, which is not preferred.

[0049] As described above, a carbon material that can be used as a semiconductor base is used as the carbon substrate 2, and silicon carbide is used as the thin film 3. The thin film 3 is formed on the entire surface of the carbon substrate 2, and has the function of preventing dust from the carbon substrate 2, outward diffusion of impurities, or protecting the entire surface of the carbon substrate 2, and suppressing the warping of the carbon substrate 2.

[0050] Here, in Figure 2 The ratio of the average value of the film thickness t2 of the thin film 3B formed on the other main surface F2 of the susceptor 1 to the average value of the film thickness t1 of the thin film 3F formed on the main surface F1 of the susceptor 1 is preferably set between 0.7 and 1.2.

[0051] If the ratio is less than 0.7, a difference in thermal conductivity will occur in an epitaxial film formation process using the susceptor, making it difficult to obtain a uniform epitaxial film.

[0052] On the other hand, if the ratio is larger than 1.2, in addition to the difference in thermal conductivity due to the variation in the film thickness of the thin film 3, warping of the susceptor is likely to occur, and the epitaxial film becomes non-uniform.

[0053] In addition, in the main surface F1 of the susceptor 1 , the film thickness difference d1 between the central portion O and the outer edge portion F1a is preferably formed to be 40% or less of the average value of the film thickness t1 of the thin film 3F formed on the main surface F1 .

[0054] In the main surface F1 of the susceptor 1 , the film thickness difference d2 between the maximum film thickness and the minimum film thickness of the outer edge portion F1a is preferably formed to be 40% or less of the average film thickness t1 of the thin film 3F formed on the main surface F1 .

[0055] When the film thickness difference d1 or d2 is 40% or less of the average value of the film thickness t1, the uniformity of heat conduction of the main surface F1 becomes good, and a uniform epitaxial film can be obtained in an epitaxial film forming process using the susceptor.

[0056] On the other hand, if the film thickness difference is larger than 40% of the average value of the film thickness t1, unevenness tends to occur, and the heat conduction of the main surface F1 becomes uneven, which may make it difficult to obtain a uniform epitaxial film.

[0057] In addition, the base 1 is formed so that, within the temperature range (900°C to 1300°C) in the epitaxial film forming process, the deviation of the emissivity of the chip mounting surface (main surface F1) is within 3%, and the ratio of the average emissivity of the chip mounting surface to its back side (the other main surface F2) is 1:1 to 1:0.8.

[0058] In addition, it is preferable that the back surface (the other main surface F2 ) of the wafer placement surface is formed so that the variation of the emissivity within the same surface is within 3%.

[0059] By setting the emissivity of the susceptor 1 to be such, the variation in the thermal conductivity of the susceptor is suppressed and the temperature non-uniformity is not generated. Therefore, the temperature of the mounted wafer can be made uniform and the film thickness variation of the epitaxial film can be prevented.

[0060] The base 1 as described above can be used, for example, Figure 3 The CVD device 5 shown is used for manufacturing.

[0061] Figure 3 The CVD device 5 shown has: a chamber 10 forming a processing space; a gas inlet 11, which is arranged on the side of the chamber 10 for supplying a carrier gas (hydrogen gas) into the chamber 10; and a gas outlet 12, which is arranged on the side of the chamber 10 opposite to the inlet 11.

[0062] The CVD device 5 also includes: a support portion 20, which is used to support the lower surface side of the carbon substrate 2 of the base 1 in the chamber 10; and a columnar protective component 13, which is arranged in plurality around the carbon substrate 2 to support the side circumference (outer periphery) of the carbon substrate 2 in a manner that allows sliding contact.

[0063] The support portion 20 has a plurality of support legs 20a to 20d, and the plurality of support legs 20a to 20d are configured such that a roller 22 provided in a manner that can be rotated at a constant speed by a motor 21 rotates along the circumferential direction of the carbon substrate 2. Figure 3 In the figure, the support leg 20c is blocked by the support leg 20a and is not shown. The rollers 22 of each support leg 20a to 20d are configured to abut against the peripheral edge of the back side of the carbon substrate 2, and each roller 22 rotates in one direction, thereby supporting the carbon substrate 2 and rotating around the center O. In addition, the rotational action (rotation start, stop, rotation direction, rotation speed) of the rollers 22 of each support leg 20a to 20d is controlled in a synchronous manner by a control unit not shown.

[0064] In addition, if Figure 3As shown, heater units 15 are provided above and below the chamber 10 , and are configured to be able to raise the temperature inside the furnace to a predetermined temperature.

[0065] When the susceptor 1 is manufactured using the CVD apparatus 5 , the carbon substrate 2 made of a carbon material and having a circular countersunk portion formed in advance is disposed on the supporting legs 20 a to 20 d in the chamber 10 .

[0066] Next, the rollers 22 of the supporting legs 20a to 20d start rotating at a predetermined rotation speed by a control unit (not shown). As a result, the carbon substrate 2 rotates around the center portion O at a predetermined speed (eg, 0.1 rpm).

[0067] Furthermore, the heater unit 15 is driven to raise the temperature in the chamber 10 to, for example, 500° C., and suction is performed from the gas outlet 12 to bring the chamber 10 into a vacuum state.

[0068] Next, a carrier gas (H2) is introduced into the chamber 10 at a predetermined flow rate from the gas inlet 11. After that, the temperature in the chamber 10 is raised to, for example, 1300°C, and the raw material gas (SiCl4, C3H8) is introduced together with the carrier gas for a predetermined time. The raw material gas concentration in the chamber 10 at the start of the introduction is set to, for example, 15% to 20%.

[0069] Here, the raw material gas flows along the upper and lower surfaces of the carbon substrate 2 via the carrier gas and is discharged from the gas outlet 12 .

[0070] In addition, the carbon substrate 2 is rotated about the center portion O by a plurality of rotationally driven rollers 22 arranged in a manner to support the peripheral portion of the lower surface side of the carbon substrate 2, so that the supporting position of the peripheral portion of the lower surface side of the carbon substrate 2 will not become the same position (it is not fixed but changes), thereby improving the uniformity of the film thickness of the formed film.

[0071] The source gas is supplied into the chamber 10 for a predetermined time (eg, 14 hours) so that the formed film reaches a predetermined thickness (eg, 60 μm or more).

[0072] Then, at the final stage of the raw material gas supply process (for example, a stage 5 to 60 minutes before the end), the raw material gas is diluted stepwise to 1 / 2 to 1 / 4 of the normal concentration.

[0073] As a result, the raw material gas becomes thinner than usual, the film formation rate is lower than usual, and the film is formed in a state where the size of the grains is uniform. As a result, the film formation amount in the surface is easy to become uniform, and the emissivity in the same surface can be made closer to constant. Specifically, the deviation of the emissivity of the wafer mounting surface (and its back side) is adjusted to within 3%, and the ratio of the average emissivity of the wafer mounting surface and its back side is adjusted to 1:1 to 1:0.8.

[0074] When the preset supply time of the raw material gas has elapsed, the supply of the raw material gas is stopped, and further, after a predetermined time has elapsed (for example, after one hour), the rotation of the roller 22 is stopped.

[0075] By these treatments, a thin film 3 containing silicon carbide is formed on the carbon substrate 2, thereby manufacturing the susceptor 1 of the present invention. During the period when the carbon substrate 2 is exposed to the raw material gas, the position of the carbon substrate 2 supported in the chamber 10 is always changed, so the uniformity of the film thickness of the thin film 3 is formed. That is, in the obtained susceptor 1, the ratio of the average value of the film thickness t2 of the thin film 3B formed on its other main surface F2 to the average value of the film thickness t1 of the thin film 3F formed on its main surface F1 is preferably formed in the range of 0.7 to 1.2. In addition, in the main surface F1 of the susceptor 1, the film thickness difference d1 between the center portion O and the outer edge portion F1a, and the film thickness difference d2 between the maximum film thickness and the minimum film thickness of the outer edge portion F1a are preferably formed to be less than 40% of the average value of the film thickness t1 of the thin film 3F formed on the main surface F1.

[0076] As described above, according to the embodiment of the present invention, in the base 1, the film thickness uniformity of the thin film 3 formed on the carbon substrate 2 is formed to be high, thereby, the deviation of the emissivity of the chip mounting surface is within 3%, and the ratio of the average emissivity of the chip mounting surface and its back side is 1:1 to 1:0.8.

[0077] In addition, it is preferred that the ratio of the average value of the film thickness t2 of the thin film 3B formed on the other main surface F2 of the base 1 to the average value of the film thickness t1 of the thin film 3F formed on the main surface F1 is formed to be between 0.7 and 1.2, and on the main surface F1 of the base 1, the film thickness difference d1 between the center portion O and the outer edge portion F1a or the film thickness difference d2 between the maximum film thickness and the minimum film thickness of the outer edge portion F1a is formed to be less than 40% of the average value of the film thickness t1 of the thin film 3F formed on the main surface F1.

[0078] This improves the uniformity of the thin film 3 formed on the surface of the carbon substrate 2 , prevents temperature non-uniformity from occurring in the susceptor 1 , and improves the uniformity of heat conduction in the main surface F1 .

[0079] As a result, in the epitaxial film forming process on a silicon wafer using the susceptor, a uniform epitaxial film can be obtained.

[0080] Furthermore, when a thin film including silicon carbide is formed on a carbon substrate 2 including a carbon material by CVD, by making the support position of the carbon substrate 2 unfixed, a uniform thin film can be formed with respect to the entire carbon substrate 2. In addition, there is no need to remove the carbon substrate 2 from the chamber in the middle of thin film formation as in the past, and a single-layer thin film that can suppress contamination can be formed.

[0081] In the above-described embodiment, as a method of suppressing the variation in emissivity within the same surface of the wafer mounting surface (and the back surface), the raw material gas is diluted at the final stage of the raw material gas supply process, but the present invention is not limited to this example.

[0082] Furthermore, in the above-described embodiment, the base having the countersunk portion is described as an example, but the present invention is not limited to this embodiment and can also be applied to a base having no countersunk portion.

[0083] In addition, when a counterbore portion is provided, the present invention is not limited to a cylindrical counterbore portion as shown in the figure, and for example, the present invention can also be applied to a base having a counterbore portion curved in a concave shape.

[0084] [Example]

[0085] The base and the manufacturing method thereof according to the present invention will be further described based on embodiments.

[0086] [Experiment 1]

[0087] In Experiment 1, isotropic graphite was used as the material of the base material of the susceptor, and a plurality of carbon base materials with countersunk portions formed thereon were prepared. Figure 3 The CVD apparatus shown forms a silicon carbide film on the surface of a substrate under a plurality of film thickness formation conditions.

[0088] In the above CVD device, a carbon substrate is placed in a chamber, and after evacuation, the temperature in the chamber is raised to 500°C, and a carrier gas (H2) is introduced into the chamber. Next, the temperature in the chamber is raised to 1300°C, and the substrate is rotated at a rotation speed of 0.1 rpm without fixing the supporting position of the carbon substrate, and raw material gas (SiCl4, C3H8) is supplied along the front and back sides of the carbon substrate. After a predetermined time (14 hours), the supply of raw material gas is stopped, and after 1 hour, the rotation of the carbon substrate is stopped, and a silicon carbide film with a thickness of 70 μm is formed on the surface of the substrate.

[0089] Here, in the above-mentioned raw material gas supply process (14 hours), the concentration of the raw material gas is diluted and thinned in the final stage (0.2 hours before the end) to suppress the deviation of the emissivity of the wafer mounting surface and the back surface of the formed susceptor.

[0090] In addition, as the conditions of Examples 1 to 4 and Comparative Examples 1 to 3, the deviation of the emissivity is set, and the deviation of the emissivity is adjusted by the raw material gas concentration. It should be noted that the emissivity of the wafer mounting surface and its back side is measured by using FTIR (Fourier transform infrared spectroscopy) and integrating sphere method manufactured by Thermo Fisher at 4 points in total at 120° intervals at the center of the wafer mounting surface of the carbon substrate and at a position of 50% of the radius of the mounting surface from the center to the outer peripheral side. The average emissivity is calculated by the average value of the above 4 points, and the emissivity deviation is calculated by (maximum value - minimum value) ÷ average value of the above 4 points. In addition, the back side of the wafer mounting surface is also measured and calculated at the same measurement position as the wafer mounting surface.

[0091] In Example 1, the emissivity deviation of the wafer mounting surface of the carbon substrate was 1%, the emissivity deviation of the back surface of the wafer mounting surface was 1%, and the average emissivity ratio of the wafer mounting surface and the back surface was 1:1.

[0092] In Example 2, the emissivity deviation of the wafer mounting surface of the carbon substrate was 2%, the emissivity deviation of the back surface of the wafer mounting surface was 1%, and the average emissivity ratio of the wafer mounting surface to the back surface was 1:0.9.

[0093] In Example 3, the emissivity deviation of the wafer mounting surface of the carbon substrate was 3%, the emissivity deviation of the back surface of the wafer mounting surface was 1%, and the average emissivity ratio of the wafer mounting surface to the back surface was 1:0.8.

[0094] In Example 4, the emissivity deviation of the wafer mounting surface of the carbon substrate was 1%, the emissivity deviation of the back surface of the wafer mounting surface was 3%, and the average emissivity ratio of the wafer mounting surface to the back surface was 1:0.8.

[0095] In Example 5, the emissivity deviation of the wafer mounting surface of the carbon substrate was 2%, the emissivity deviation of the back surface of the wafer mounting surface was 4%, and the average emissivity ratio of the wafer mounting surface to the back surface was 1:0.8.

[0096] In Comparative Example 1, the emissivity variation of the wafer mounting surface of the carbon substrate was 4%, the emissivity variation of the back surface of the wafer mounting surface was 3%, and the average emissivity ratio of the wafer mounting surface to the back surface was 1:0.9.

[0097] In Comparative Example 2, the emissivity variation of the wafer mounting surface of the carbon substrate was 3%, the emissivity variation of the back surface of the wafer mounting surface was 3%, and the average emissivity ratio of the wafer mounting surface to the back surface was 1:0.7.

[0098] Using the susceptors manufactured in Examples 1 to 5 and Comparative Examples 1 and 2, a process of forming an epitaxial film was performed on a silicon wafer.

[0099] The results of Experiment 1 are shown in Table 1. The conditions shown in Table 1 were evaluated by the uniformity of the epitaxial film formed on the silicon wafer. For the in-plane distribution of the film thickness of the epitaxial film, the case of ±5% or less was marked as ○, the case of more than ±5% and less than 7% was marked as △, and the case of more than ±7% was marked as ×.

[0100] [Table 1]

[0101]

[0102] Based on the results of Experiment 1 above, it was confirmed that when a silicon carbide thin film with a thickness of 70 μm was formed on the surface of the substrate, the deviation of the emissivity of the chip mounting surface (front side) was within 3%, and the ratio of the average emissivity of the chip mounting surface to its back side was 1:1 to 1:0.8, thereby improving the uniformity of the epitaxial film formed on the silicon wafer.

[0103] [Experiment 2]

[0104] In Experiment 2, the thickness of the silicon carbide thin film on the surface of the substrate was changed to 30 μm, and the other conditions were the same as those in Experiment 1, and evaluation was performed.

[0105] In Example 6, the emissivity deviation of the wafer mounting surface of the carbon substrate was 1%, the emissivity deviation of the back surface of the wafer mounting surface was 1%, and the average emissivity ratio of the wafer mounting surface and the back surface was 1:1.

[0106] In Example 7, the emissivity deviation of the wafer mounting surface of the carbon substrate was 2%, the emissivity deviation of the back surface of the wafer mounting surface was 1%, and the average emissivity ratio of the wafer mounting surface to the back surface was 1:0.9.

[0107] In Example 8, the emissivity deviation of the wafer mounting surface of the carbon substrate was 3%, the emissivity deviation of the back surface of the wafer mounting surface was 1%, and the average emissivity ratio of the wafer mounting surface to the back surface was 1:0.8.

[0108] In Example 9, the emissivity deviation of the wafer mounting surface of the carbon substrate was 1%, the emissivity deviation of the back surface of the wafer mounting surface was 3%, and the average emissivity ratio of the wafer mounting surface to the back surface was 1:0.8.

[0109] In Example 10, the emissivity deviation of the wafer mounting surface of the carbon substrate was 2%, the emissivity deviation of the back surface of the wafer mounting surface was 4%, and the average emissivity ratio of the wafer mounting surface to the back surface was 1:0.8.

[0110] In Comparative Example 3, the emissivity variation of the wafer mounting surface of the carbon substrate was 4%, the emissivity variation of the back surface of the wafer mounting surface was 3%, and the average emissivity ratio of the wafer mounting surface to the back surface was 1:0.9.

[0111] In Comparative Example 4, the emissivity variation of the wafer mounting surface of the carbon substrate was 3%, the emissivity variation of the back surface of the wafer mounting surface was 3%, and the average emissivity ratio of the wafer mounting surface to the back surface was 1:0.7.

[0112] Using the susceptors manufactured in Examples 6 to 10 and Comparative Examples 3 and 4, a process of forming an epitaxial film was performed on a silicon wafer.

[0113] The results of Experiment 2 are shown in Table 2. The conditions shown in Table 2 were evaluated by the uniformity of the epitaxial film formed on the silicon wafer. For the in-plane distribution of the film thickness of the epitaxial film, the case of ±5% or less was marked as ○, the case of more than ±5% and less than 7% was marked as △, and the case of more than ±7% was marked as ×.

[0114] [Table 2]

[0115]

[0116] According to the results of Experiment 2 shown in Table 2, it was confirmed that when a silicon carbide thin film with a thickness of 30 μm was formed on the surface of the substrate, the deviation of the emissivity of the chip mounting surface (front side) was within 3%, and the ratio of the average emissivity of the chip mounting surface to its back side was 1:1 to 1:0.8, thereby improving the uniformity of the epitaxial film formed on the silicon wafer.

[0117] [Experiment 3]

[0118] In Experiment 3, the thickness of the silicon carbide thin film on the surface of the substrate was changed to 60 μm, and the other conditions were the same as those in Experiment 1, and evaluation was performed.

[0119] In Example 11, the emissivity deviation of the wafer mounting surface of the carbon substrate was 1%, the emissivity deviation of the back surface of the wafer mounting surface was 1%, and the average emissivity ratio between the wafer mounting surface and the back surface was 1:1.

[0120] In Example 12, the emissivity deviation of the wafer mounting surface of the carbon substrate was 2%, the emissivity deviation of the back surface of the wafer mounting surface was 1%, and the average emissivity ratio of the wafer mounting surface to the back surface was 1:0.9.

[0121] In Example 13, the emissivity deviation of the wafer mounting surface of the carbon substrate was 3%, the emissivity deviation of the back surface of the wafer mounting surface was 1%, and the average emissivity ratio of the wafer mounting surface to the back surface was 1:0.8.

[0122] In Example 14, the emissivity deviation of the wafer mounting surface of the carbon substrate was 1%, the emissivity deviation of the back surface of the wafer mounting surface was 3%, and the average emissivity ratio of the wafer mounting surface to the back surface was 1:0.8.

[0123] In Example 15, the emissivity deviation of the wafer mounting surface of the carbon substrate was 2%, the emissivity deviation of the back surface of the wafer mounting surface was 4%, and the average emissivity ratio of the wafer mounting surface to the back surface was 1:0.8.

[0124] In Comparative Example 5, the emissivity variation of the wafer mounting surface of the carbon substrate was 4%, the emissivity variation of the back surface of the wafer mounting surface was 3%, and the average emissivity ratio of the wafer mounting surface to the back surface was 1:0.9.

[0125] In Comparative Example 6, the emissivity variation of the wafer mounting surface of the carbon substrate was 3%, the emissivity variation of the back surface of the wafer mounting surface was 3%, and the average emissivity ratio of the wafer mounting surface to the back surface was 1:0.7.

[0126] Using the susceptors manufactured in Examples 11 to 15 and Comparative Examples 5 and 6, a process of forming an epitaxial film was performed on a silicon wafer.

[0127] The results of Experiment 3 are shown in Table 3. The conditions shown in Table 3 were evaluated by the uniformity of the epitaxial film formed on the silicon wafer. For the in-plane distribution of the film thickness of the epitaxial film, the case of ±5% or less was marked as ○, the case of more than ±5% and less than 7% was marked as △, and the case of more than ±7% was marked as ×.

[0128] [Table 3]

[0129]

[0130] According to the results of Experiment 3 shown in Table 3, it was confirmed that when a silicon carbide thin film with a thickness of 60 μm was formed on the surface of the substrate, the deviation of the emissivity of the chip mounting surface (front side) was within 3%, and the ratio of the average emissivity of the chip mounting surface to its back side was 1:1 to 1:0.8, thereby improving the uniformity of the epitaxial film formed on the silicon wafer.

[0131] [Experiment 4]

[0132] In Experiment 4, the thickness of the silicon carbide thin film on the surface of the substrate was changed to 140 μm, and the other conditions were evaluated in the same manner as in Experiment 1.

[0133] In Example 16, the emissivity deviation of the wafer mounting surface of the carbon substrate was 1%, the emissivity deviation of the back surface of the wafer mounting surface was 1%, and the average emissivity ratio between the wafer mounting surface and the back surface was 1:1.

[0134] In Example 17, the emissivity deviation of the wafer mounting surface of the carbon substrate was 2%, the emissivity deviation of the back surface of the wafer mounting surface was 1%, and the average emissivity ratio of the wafer mounting surface and the back surface was 1:0.9.

[0135] In Example 18, the emissivity deviation of the wafer mounting surface of the carbon substrate was 3%, the emissivity deviation of the back surface of the wafer mounting surface was 1%, and the average emissivity ratio of the wafer mounting surface to the back surface was 1:0.8.

[0136] In Example 19, the emissivity deviation of the wafer mounting surface of the carbon substrate was 1%, the emissivity deviation of the back surface of the wafer mounting surface was 3%, and the average emissivity ratio of the wafer mounting surface to the back surface was 1:0.8.

[0137] In Example 20, the emissivity deviation of the wafer mounting surface of the carbon substrate was 2%, the emissivity deviation of the back surface of the wafer mounting surface was 4%, and the average emissivity ratio of the wafer mounting surface to the back surface was 1:0.8.

[0138] In Comparative Example 7, the emissivity variation of the wafer mounting surface of the carbon substrate was 4%, the emissivity variation of the back surface of the wafer mounting surface was 3%, and the average emissivity ratio of the wafer mounting surface to the back surface was 1:0.9.

[0139] In Comparative Example 8, the emissivity variation of the wafer mounting surface of the carbon substrate was 3%, the emissivity variation of the back surface of the wafer mounting surface was 3%, and the average emissivity ratio of the wafer mounting surface to the back surface was 1:0.7.

[0140] Using the susceptors manufactured in Examples 16 to 20 and Comparative Examples 7 and 8, a process of forming an epitaxial film was performed on a silicon wafer.

[0141] The results of Experiment 4 are shown in Table 4. The conditions shown in Table 4 were evaluated by the uniformity of the epitaxial film formed on the silicon wafer. For the in-plane distribution of the film thickness of the epitaxial film, the case of ±5% or less was marked as ○, the case of more than ±5% and less than 7% was marked as △, and the case of more than ±7% was marked as ×.

[0142] [Table 4]

[0143]

[0144] According to the results of Experiment 4 shown in Table 4, it was confirmed that when a silicon carbide thin film with a thickness of 140 μm was formed on the surface of the substrate, the deviation of the emissivity of the chip mounting surface (front side) was within 3%, and the ratio of the average emissivity of the chip mounting surface to its back side was 1:1 to 1:0.8, thereby improving the uniformity of the epitaxial film formed on the silicon wafer.

[0145] [Experiment 5]

[0146] In Experiment 5, the thickness of the silicon carbide thin film on the surface of the substrate was changed to 200 μm, and the other conditions were the same as those in Experiment 1, and evaluation was performed.

[0147] In Example 21, the emissivity deviation of the wafer mounting surface of the carbon substrate was 1%, the emissivity deviation of the back surface of the wafer mounting surface was 1%, and the average emissivity ratio between the wafer mounting surface and the back surface was 1:1.

[0148] In Example 22, the emissivity deviation of the wafer mounting surface of the carbon substrate was 2%, the emissivity deviation of the back surface of the wafer mounting surface was 1%, and the average emissivity ratio of the wafer mounting surface to the back surface was 1:0.9.

[0149] In Example 23, the emissivity deviation of the wafer mounting surface of the carbon substrate was 3%, the emissivity deviation of the back surface of the wafer mounting surface was 1%, and the average emissivity ratio of the wafer mounting surface to the back surface was 1:0.8.

[0150] In Example 24, the emissivity deviation of the wafer mounting surface of the carbon substrate was 1%, the emissivity deviation of the back surface of the wafer mounting surface was 3%, and the average emissivity ratio of the wafer mounting surface to the back surface was 1:0.8.

[0151] In Example 25, the emissivity deviation of the wafer mounting surface of the carbon substrate was 2%, the emissivity deviation of the back surface of the wafer mounting surface was 4%, and the average emissivity ratio of the wafer mounting surface to the back surface was 1:0.8.

[0152] In Comparative Example 9, the emissivity variation of the wafer mounting surface of the carbon substrate was 4%, the emissivity variation of the back surface of the wafer mounting surface was 3%, and the average emissivity ratio of the wafer mounting surface to the back surface was 1:0.9.

[0153] In Comparative Example 10, the emissivity variation of the wafer mounting surface of the carbon substrate was 3%, the emissivity variation of the back surface of the wafer mounting surface was 3%, and the average emissivity ratio of the wafer mounting surface to the back surface was 1:0.7.

[0154] Using the susceptors manufactured in Examples 21 to 25 and Comparative Examples 9 and 10, a process of forming an epitaxial film was performed on a silicon wafer.

[0155] The results of Experiment 5 are shown in Table 5. The conditions shown in Table 5 were evaluated by the uniformity of the epitaxial film formed on the silicon wafer. The in-plane distribution of the film thickness of the epitaxial film was evaluated as ○ when it was less than ±5%, △ when it was more than ±5% and less than 7%, and × when it was more than ±7%.

[0156] [Table 5]

[0157]

[0158] According to the results of Experiment 5 shown in Table 5, it was confirmed that when a silicon carbide thin film with a thickness of 200 μm was formed on the surface of the substrate, the deviation of the emissivity of the chip mounting surface (front surface) was within 3%, and the ratio of the average emissivity of the chip mounting surface to its back surface was 1:1 to 1:0.8, thereby improving the uniformity of the epitaxial film formed on the silicon wafer.

[0159] Based on the results of the above experiments 1 to 5, it was confirmed that when the thickness of the silicon carbide film formed on the surface of the substrate is any condition, by setting the deviation of the emissivity of the chip mounting surface (front side) to within 3%, and setting the ratio of the average emissivity of the chip mounting surface to its back side to 1:1 to 1:0.8, the uniformity of the epitaxial film formed on the silicon wafer becomes good.

[0160] Furthermore, it was confirmed that more preferably, by setting the variation in the emissivity of the back surface of the susceptor to within 3%, the uniformity of the epitaxial film formed on the silicon wafer can be further improved.

[0161] [Experiment 6]

[0162] In Experiment 6, the preferred film thickness of the silicon carbide film formed on the surface of the carbon substrate was studied. In Examples 26 to 33, the film thickness was adjusted by the supply time of the raw material gas. Furthermore, in Experiment 6, at the final stage of the raw material gas supply process, the raw material gas was diluted so that the deviation of the emissivity of the wafer mounting surface and the back surface of the obtained susceptor was set to within 3%, and the ratio of the average emissivity of the wafer mounting surface and its back surface was adjusted to a range of 1:1 to 1:0.8.

[0163] Then, using the obtained susceptor, epitaxial film formation and cleaning were repeatedly performed to verify whether a predetermined lifespan (continuous operation for 4000 hours) could be achieved.

[0164] In Example 29, the film thickness of the silicon carbide film on the main surface (wafer mounting surface) was 61 μm. In Example 30, the film thickness was 66 μm, in Example 31, it was 70 μm, in Example 32, it was 80 μm, and in Example 33, it was 100 μm.

[0165] In addition, the above-mentioned film thickness is 42 μm in Example 26, 55 μm in Example 27, and 58 μm in Example 28.

[0166] The evaluation of Experiment 6 is shown in Table 6.

[0167] [Table 6]

[0168]

[0169] As shown in Table 6, the desired life cannot be obtained in a susceptor having a silicon carbide film thickness of less than 60 μm. Therefore, it was confirmed that the silicon carbide film thickness is preferably 60 μm or more.

[0170] [Experiment 7]

[0171] In Experiment 7, isotropic graphite was used as the material of the base substrate, and a carbon substrate with a countersunk portion was prepared. Figure 3 The CVD apparatus shown forms a silicon carbide film on the surface of a substrate under a plurality of film thickness formation conditions.

[0172] Next, using the susceptor formed under the various conditions, a process of forming an epitaxial film is performed on the silicon wafer.

[0173] In the manufacture of the base, use Figure 3 The CVD apparatus shown in the figure adjusts the film thickness by increasing or decreasing the processing time when forming a silicon carbide film on the surface of the substrate of the susceptor. Furthermore, in Experiment 7, the raw material gas was diluted at the final stage of the raw material gas supply process, and the deviation of the emissivity of the wafer mounting surface and the back surface of the susceptor was set to within 3%, and the ratio of the average emissivity of the wafer mounting surface and its back surface was adjusted to a range of 1:1 to 1:0.8.

[0174] After forming the susceptor, the ratio of the average film thickness of the silicon carbide film formed on the other main surface (wafer non-mounting surface) to the average film thickness of the silicon carbide film formed on the main surface (wafer mounting surface) is calculated. It should be noted that the average film thickness of the silicon carbide film formed on the main surface (wafer mounting surface) and the average film thickness of the silicon carbide film formed on the other main surface (wafer non-mounting surface) are measured using an optical microscope at the same position as the emissivity measurement site, and their average is calculated.

[0175] As shown in Table 7, the above ratio was 0.7 in Example 36, 0.8 in Example 37, 0.9 in Example 38, 1.0 in Example 39, 1.1 in Example 40, and 1.2 in Example 41.

[0176] In addition, in Example 34, the above ratio was 0.5, in Example 35, it was 0.6, in Example 42, it was 1.3, and in Example 43, it was 1.4.

[0177] It should be noted that in Examples 34 to 43, the ratio (%) of the difference in film thickness between the center and the outer edge of the main surface (wafer mounting surface) of the susceptor to the average film thickness of the thin film formed on the main surface was set to 30%. Furthermore, the ratio (%) of the difference in film thickness between the maximum film thickness and the minimum film thickness of the outer edge of the main surface (wafer mounting surface) of the susceptor to the average film thickness of the thin film formed on the main surface was set to 30%.

[0178] The results of Experiment 7 are shown in Table 7. The conditions shown in Table 7 were evaluated by the uniformity of the epitaxial film formed on the silicon wafer. For the in-plane distribution of the film thickness of the epitaxial film, the case of ±5% or less was marked as ○, the case of more than ±5% and less than 7% was marked as △, and the case of more than ±7% was marked as ×.

[0179] [Table 7]

[0180] Film thickness ratio evaluate Embodiment 34 0.5 △ Embodiment 35 0.6 △ Embodiment 36 0.7 ○ Embodiment 37 0.8 ○ Embodiment 38 0.9 ○ Embodiment 39 1.0 ○ Embodiment 40 1.1 ○ Embodiment 41 1.2 ○ Embodiment 42 1.3 △ Embodiment 43 1.4 △

[0181] Based on the results of Experiment 7, it was confirmed that if the ratio of the average film thickness of the silicon carbide film formed on the other main surface of the base (the non-wafer loading surface) to the average film thickness of the silicon carbide film formed on the main surface of the base (the chip loading surface) is in the range of 0.7 to 1.2, the uniformity of the film thickness of the epitaxial film becomes good.

[0182] [Experiment 8]

[0183] In Experiment 8, we used the same Figure 3 The CVD apparatus shown forms a silicon carbide film on the surface of a substrate under a plurality of film thickness formation conditions.

[0184] Next, using the susceptor formed under the various conditions, a process of forming an epitaxial film is performed on the silicon wafer.

[0185] In the manufacture of the base, use Figure 3 The CVD apparatus shown in the figure adjusts the film thickness by increasing or decreasing the processing time when forming a silicon carbide film on the surface of the substrate of the susceptor. Then, in the final stage of the raw material gas supply process, the raw material gas is diluted, and the deviation of the emissivity of the wafer mounting surface and the back surface of the susceptor is set to within 3%, and the ratio of the average emissivity of the wafer mounting surface and its back surface is adjusted to a range of 1:1 to 1:0.8.

[0186] After the thin film formation was completed, the ratio (%) of the difference in film thickness between the center and the outer edge of the main surface (wafer mounting surface) of the susceptor taken out from the CVD apparatus to the average film thickness of the thin film formed on the main surface was calculated.

[0187] The above ratio is 0% in Example 44, 10% in Example 45, 20% in Example 46, 30% in Example 47, and 40% in Example 48.

[0188] In addition, the above ratio is 50% in Example 49 and 60% in Example 50.

[0189] It should be noted that in Examples 44 to 50, the ratio of the average film thickness of the silicon carbide film formed on the other main surface (wafer non-mounting surface) of the susceptor to the average film thickness of the silicon carbide film formed on the main surface (wafer mounting surface) of the susceptor was set to 1.0. Furthermore, on the main surface (wafer mounting surface) of the susceptor, the ratio (%) of the film thickness difference between the maximum film thickness and the minimum film thickness at the outer edge portion to the average film thickness of the thin film formed on the main surface was set to 30%.

[0190] The results of Experiment 8 are shown in Table 8. The conditions shown in Table 8 were evaluated by the uniformity of the epitaxial film formed on the silicon wafer in the same manner as Experiment 7. For the in-plane distribution of the film thickness of the epitaxial film, the case of ±5% or less was marked as ○, the case of more than ±5% and less than 7% was marked as △, and the case of more than ±7% was marked as ×.

[0191] [Table 8]

[0192] Proportion(%) evaluate Embodiment 44 0 ○ Embodiment 45 10 ○ Embodiment 46 20 ○ Embodiment 47 30 ○ Embodiment 48 40 ○ Embodiment 49 50 △ Embodiment 50 60 △

[0193] According to the results of Experiment 8, it was confirmed that on the main surface of the susceptor (wafer mounting surface), if the difference in film thickness between the center and the outer edge is in the range of 0% to 40% of the average film thickness of the thin film formed on the main surface, the film thickness uniformity of the epitaxial film becomes good.

[0194] [Experiment 9]

[0195] In Experiment 9, we used the same Figure 3 The CVD apparatus shown forms a silicon carbide film on the surface of a substrate under a plurality of film thickness formation conditions.

[0196] Next, using the susceptor formed under the various conditions, a process of forming an epitaxial film is performed on the silicon wafer.

[0197] In the manufacture of the base, use Figure 3 The CVD apparatus shown in the figure adjusts the film thickness by increasing or decreasing the processing time when forming a silicon carbide film on the surface of the substrate of the susceptor. Then, in the final stage of the raw material gas supply process, the raw material gas is diluted, and the deviation of the emissivity of the wafer mounting surface and the back surface of the susceptor is set to within 3%, and the ratio of the average emissivity of the wafer mounting surface and its back surface is adjusted to a range of 1:1 to 1:0.8.

[0198] After the thin film formation is completed, on the main surface (wafer mounting surface) of the susceptor taken out from the CVD device, the ratio (%) of the film thickness difference between the maximum film thickness and the minimum film thickness at the outer edge portion to the average film thickness of the formed thin film on the main surface is calculated.

[0199] The above ratio is 0% in Example 51, 10% in Example 52, 20% in Example 53, 30% in Example 54, and 40% in Example 55.

[0200] In addition, the above ratio is 50% in Example 56 and 60% in Example 57.

[0201] It should be noted that in Examples 51 to 57, the ratio of the average film thickness of the silicon carbide film formed on the other main surface (wafer non-mounting surface) of the susceptor to the average film thickness of the silicon carbide film formed on the main surface (wafer mounting surface) of the susceptor was set to 1.0. Furthermore, in the main surface (wafer mounting surface) of the susceptor, the ratio (%) of the film thickness difference between the center and the outer edge to the average film thickness of the thin film formed on the main surface was set to 30%.

[0202] The results of Experiment 9 are shown in Table 9. As in Experiments 7 and 8, the conditions shown in Table 9 were evaluated by the uniformity of the epitaxial film formed on the silicon wafer. For the in-plane distribution of the film thickness of the epitaxial film, the case of ±5% or less was marked as ○, the case of more than ±5% and less than 7% was marked as △, and the case of more than ±7% was marked as ×.

[0203] [Table 9]

[0204] Proportion(%) evaluate Embodiment 51 0 ○ Embodiment 52 10 ○ Embodiment 53 20 ○ Embodiment 54 30 ○ Embodiment 55 40 ○ Embodiment 56 50 △ Embodiment 57 60 △

[0205] According to the results of Experiment 9, it was confirmed that on the main surface of the base (chip mounting surface), if the difference between the maximum film thickness and the minimum film thickness in the outer edge portion is in the range of 0% to 40% of the average film thickness of the thin film formed on the main surface, the film thickness uniformity of the epitaxial film becomes good.

[0206] This application is based on Japanese Patent Application No. 2021-105175 filed on June 24, 2021 and Japanese Patent Application No. 2022-071844 filed on April 25, 2022, the contents of which are incorporated herein by reference.

Claims

1. A base, characterized in that: The base has a disc-shaped substrate having no through-holes and made of a carbon material, and has one main surface on which a silicon wafer is mounted and another main surface facing the one main surface. The entire surface of the substrate is covered with a thin film comprising silicon carbide, The deviation of the emissivity of the one main surface is within 3%, and the ratio of the average emissivity of the one main surface and the other main surface facing the one main surface is 1:1 to 1:0.

8.

2. The base according to claim 1, characterized in that: The variation in emissivity of the other main surface facing the one main surface is within 3%.

3. The base according to claim 1, characterized in that: The ratio of the film thickness of the thin film formed on the other main surface to the film thickness of the thin film formed on the one main surface is greater than 0.7 and less than 1.2, and in the one main surface, the difference in film thickness between the central portion and the outer edge portion is less than 40% of the average film thickness of the thin film formed on the one main surface, and the difference in film thickness between the maximum film thickness and the minimum film thickness at the outer edge portion of the one main surface is less than 40% of the average film thickness of the thin film formed on the one main surface.

4. The base according to any one of claims 1 to 3, characterized in that A countersunk portion is formed on the one main surface.

5. A method for manufacturing a base, characterized in that: A method for manufacturing a susceptor according to any one of claims 1 to 4, The manufacturing method comprises the following steps: In the chamber, a disc-shaped substrate having no through-holes and containing a carbon material is supported while a supporting position thereof is moved. The raw material gas is supplied in a direction parallel to the one main surface of the substrate, and a thin film including silicon carbide is formed on the entire surface of the substrate.

Images