Epitaxial wafer

Abstract

To provide an epitaxial wafer that has a low-defect heteroepitaxial film without depending on the dopant concentration and the kind of a silicon wafer.SOLUTION: An epitaxial wafer has a silicon substrate, and an epitaxial film of semiconductor material different from silicon formed on the substrate. When the film thickness in a wafer center part of the epitaxial film is defined as 1, the film thickness in a wafer outer peripheral part is less than 1.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an epitaxial wafer in which an epitaxial film of a semiconductor material different from silicon is formed on a silicon substrate. [Background technology]

[0002] For wafers used in cutting-edge devices, semiconductor materials other than silicon, such as silicon germanium, silicon carbide, and gallium nitride, are now being considered as candidates. However, when heteroepitaxial growth is performed on silicon wafers, stress is applied due to the difference in lattice constants between silicon and the epitaxial film, and excessive stress can cause stacking faults and threading dislocations.

[0003] In conventional heteroepitaxial growth, a method has been proposed to suppress stress by using low-resistance silicon wafers containing high-concentration dopants (Patent Document 1). However, this also leads to other problems such as autodoping due to outward diffusion of dopants from the wafer. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Patent No. 4972330 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The present invention has been made in view of the above circumstances, and aims to provide an epitaxial wafer having a low-defect heteroepitaxial film, regardless of the dopant concentration or type of silicon substrate. [Means for solving the problem]

[0006] To achieve the above objective, the present invention provides an epitaxial wafer in which an epitaxial film of a semiconductor material different from silicon is formed on a silicon substrate, The present invention provides an epitaxial wafer characterized in that the epitaxial film has a film thickness of less than 1 at the outer periphery of the wafer, when the film thickness at the center of the wafer is taken as 1.

[0007] With such an epitaxial wafer according to the present invention, a low-defect heteroepitaxial wafer with low stacking fault density and through-dislocation density is obtained, regardless of the dopant concentration or type of silicon substrate.

[0008] In this case, the outer periphery of the wafer can be in the range up to 5 mm inward from the outer periphery, preferably in the range up to 10 mm inward from the outer periphery, and even more preferably in the range up to 20 mm inward from the outer periphery.

[0009] Such a design would more reliably result in a low-defect epitaxial wafer. Furthermore, the wider the area around the wafer's outer edge where the film thickness is less than 1mm, the lower the defect rate will be.

[0010] Furthermore, the epitaxial film may have a film thickness of 0.95 or more and less than 1 at the outer edge of the wafer, preferably 0.9 or more and less than 1, and even more preferably 0.8 or more and less than 1.

[0011] Such a design would more reliably result in a low-defect epitaxial wafer. Furthermore, the thinner the film thickness at the outer edge of the wafer compared to the film thickness at the center, the lower the defect rate.

[0012] Furthermore, the epitaxial film may be any of the following: a silicon germanium film, a germanium film, a silicon carbide film, and a gallium nitride film.

[0013] These semiconductor materials are suitable for use in state-of-the-art devices.

[0014] Further, the epitaxial wafer may have a diameter of 300 mm or more.

[0015] In recent years, an increase in the size (large diameter) of wafers has been desired, and a wafer with a diameter of 300 mm or more can meet such needs.

Advantages of the Invention

[0016] The epitaxial wafer of the present invention has extremely reduced defects such as stacking defects and threading dislocations caused by stress due to the lattice constant difference in heteroepitaxial growth, and has excellent quality.

Brief Description of the Drawings

[0017] [Figure 1] FIG. 1 is an explanatory diagram showing an example of the epitaxial wafer of the present invention. [Figure 2] FIG. 2 is an explanatory diagram showing an example of an epitaxial growth apparatus. [Figure 3] FIG. 3 is an explanatory diagram showing an example of the arrangement of lamp arrays in a plan view. [Figure 4] FIG. 4 is an explanatory diagram showing an example of the epitaxial wafer of the present invention.

Best Mode for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto. FIG. 1 is an example of the epitaxial wafer of the present invention. As shown in FIG. 1, the epitaxial wafer 1 of the present invention has an epitaxial film 3 formed on a silicon substrate (single crystal substrate) 2.

[0019] The silicon substrate 2 is not particularly limited and can be, for example, a wafer cut from a silicon single crystal ingot manufactured by the Czochralski method or the floating zone method, and subjected to lapping, grinding, etching, polishing, etc. Furthermore, there are no particular limitations on the type, concentration, or variety of dopant (resistivity, diameter, thickness, oxygen concentration, etc.), and these can be determined as appropriate. The present invention provides high quality with reduced defect density without relying on the control of these dopants. Furthermore, the diameter of the silicon substrate 2 (the diameter of the epitaxial wafer 1) can be, for example, 300 mm or larger, and even 450 mm or larger. To meet the recent demand for larger diameters, the larger the better, and there is no particular upper limit on the diameter. Conversely, a relatively small diameter size, for example 200 mm or less, is also possible.

[0020] The epitaxial film 3 can be made of a semiconductor material other than silicon (heteroepitaxial film). For example, it can be any of the following: silicon germanium film, germanium film, silicon carbide film, and gallium nitride film. Such films are suitable as epitaxial wafers for state-of-the-art devices.

[0021] Furthermore, this epitaxial film 3 has a film thickness distribution in which the film thickness at the wafer's outer edge (hereinafter also simply referred to as the outer edge) is less than 1 when the film thickness at the wafer's center (hereinafter also simply referred to as the center) (film thickness A) is set to 1. Because the film thickness at the outer edge is thinner than at the center, lattice relaxation is less likely to occur at the outer edge, resulting in an epitaxial film 3 with excellent quality, having a low density of defects such as stacking faults and through-dislocations. The epitaxial layer 3 only needs to satisfy the above relationship in terms of film thickness distribution between the center and the outer periphery; the film thickness distribution of the inner periphery of the wafer (hereinafter simply referred to as the inner periphery), which is located between the center and the outer periphery, can be anything. For example, as shown in Figure 1, when viewed from the side, the film thickness is constant in the inner periphery including the center, the film thickness decreases towards the outer periphery near the boundary between the inner and outer periphery, and the film thickness remains constant at that thinness in the outer periphery. Alternatively, as shown in Figure 4, when viewed from the side, the film thickness is thickest in the center and gradually decreases towards the outer periphery, that is, it can have a shape that slopes gently towards the outer periphery.

[0022] The area of ​​the wafer periphery is not particularly limited, but it can be defined as, for example, the area from the outer edge of the wafer to 5 mm inward. If the outer edge, which has a thinner film thickness than the center, is maintained within this range, it is possible to more reliably produce an epitaxial wafer with fewer defects. Furthermore, it is more preferable that the outer perimeter extends 10 mm inward from the outer perimeter, and even more preferable that it extends 20 mm inward from the outer perimeter. The wider the outer perimeter, the lower the defect density can be. The size of the outer periphery can be appropriately determined depending on the diameter of the epitaxial wafer 1, but if the purpose is to reduce stress-induced defects due to lattice constant differences, then defining the outer periphery as the area from the outer edge to 50 mm inward is generally sufficient.

[0023] Furthermore, as mentioned above, when the film thickness in the center is set to 1, the film thickness in the outer periphery only needs to be less than 1, but it can be set to 0.95 or more and less than 1, in which case it is possible to more reliably achieve a low defect rate. Furthermore, it is more preferable that the film thickness on the outer periphery is 0.9 or more and less than 1, and even more preferable that it is 0.8 or more and less than 1. The smaller the film thickness on the outer periphery, the lower the defect density can be. The ratio of the film thickness at the outer periphery to the film thickness at the center can be determined depending on the diameter of the epitaxial wafer 1 and the absolute value of the desired epitaxial film thickness 3 (however, as mentioned above, it must be less than 1). However, if the purpose is to reduce stress-induced defects due to lattice constant differences, a ratio of 0.6 or more and less than 1 is generally sufficient. Furthermore, although it was stated that the film thickness of the outer periphery relative to the film thickness of the central part is less than 1, a value of 0.99 or less is preferable, and a value of 0.98 or less is even preferable, in order to ensure a lower defect rate.

[0024] Incidentally, in the case of a typical epitaxial wafer, since uniformity of film thickness is generally required for the epitaxial film, the film thickness at the center and the film thickness at the outer edge are basically the same. Also, abnormal growth of the epitaxial layer is more likely to occur at the outer edge of the wafer, and it is common for the outer edge to be thicker than the center.

[0025] Next, an epitaxial growth apparatus (RP-CVD apparatus) that can be used when manufacturing the epitaxial wafer 1 of the present invention will be described with reference to Figure 2. The single-wafer epitaxial growth apparatus 11 in Figure 2 is an apparatus for vapor-phase growth of an epitaxial film 3 of a semiconductor material other than silicon on the surface of a single silicon substrate 2.

[0026] The epitaxial growth apparatus 11 includes a chamber 12 made of a transparent quartz material or the like. Inside the chamber 12, a susceptor 13 is arranged for placing the silicon substrate 2 to be epitaxially grown. The susceptor 13 can be made of, for example, SiC, or a graphite substrate coated with SiC. The susceptor 13 is formed in a disc shape and arranged so that its upper and lower surfaces are horizontal.

[0027] A recessed counterbore 14 is formed on the upper surface of the susceptor 13, and the silicon substrate 2 is placed inside this counterbore 14. In addition, the susceptor 13 has multiple through-holes 15 that penetrate to the back surface. These through-holes 15 are, for example, holes into which lift pins 16 used to insert and remove the silicon substrate 2 into and out of the counterbore 14 are inserted, or for other purposes (for example, holes to suppress the occurrence of halo-like clouding and surface roughness on the back surface of the epitaxial wafer). Note that a type of susceptor 13 without through-holes 15 may also be used.

[0028] The back surface of the susceptor 13 is supported by a shaft 17. The shaft 17 is positioned so that its axis L coincides with the center of the susceptor 13. A drive unit 18 is connected to the shaft 17, via the shaft 17, which rotates the susceptor 13 around axis L.

[0029] Lamps 41 and 42 are positioned above and below the chamber 12 to heat the silicon substrate 2 to the epitaxial reaction temperature (e.g., 400-1200°C) during epitaxial growth. In the example shown in Figure 2, when viewed from above, the rows of lamps are arranged in a circular pattern, with three rows arranged concentrically. Specifically, the upper section has the inner row 41a, the middle row 41b, and the outer row 41c, while the lower section has the inner row 42a, the middle row 42b, and the outer row 42c. Although an example with three rows is shown here, the arrangement is not limited to this; it can also consist of only two rows, or four or more rows. For example, unlike in Figure 2, the lamps may be arranged in two rows on the silicon substrate 2, as shown in the plan view in Figure 3, with 12 lamps in the inner row and 12 lamps in the outer row, each arranged in a circular pattern. Although only the upper lamps are shown, the lower lamps are arranged in a similar manner. Naturally, the placement and number of lamps for the upper and lower, as well as the inner and outer lamps, are not limited to the patterns in Figures 2 and 3, but can be determined as appropriate. The power (output) of these lamps can be controlled individually. Therefore, for example, the power ratio (output ratio) between the upper and lower lamps can be changed, and the power ratio between each row, both inner and outer, can also be changed.

[0030] A gas supply port 19 is provided at one end of the chamber 12 in the horizontal direction, and a gas outlet 20 is provided on the opposite side from the gas supply port 19. A processing gas G containing a raw material gas for the epitaxial film 3, a carrier gas (e.g., hydrogen), and a dopant gas (e.g., a gas containing boron or phosphorus) for adjusting the conductivity type and conductivity of the epitaxial film 2 is introduced through the gas supply port 19. Examples of raw material gases include SiH4 or SiH2Cl2 and GeH4 for silicon germanium films, GeH4 for germanium films, SiH4 or SiH2Cl2 and C3H8 for silicon carbide films, and GaCl and NH3 for gallium nitride films. These are some examples. The processing gas G supplied from the gas supply port 19 flows along the surface of the silicon substrate 2, which is rotated and held almost horizontally within the internal space of the chamber 12. Subsequently, the processing gas G is discharged outside the chamber 12 from the gas outlet 20.

[0031] When performing epitaxial growth, hydrogen gas is first introduced into the chamber 12 from the gas supply port 19, and then the silicon substrate 2 is placed into the chamber 12 and mounted on the counterbore 14 of the susceptor 13. Next, the silicon substrate 2 mounted on the susceptor 13 is heated to a heat treatment temperature (for example, 1050 to 1200°C) using lamps 41a to 41c and 42a to 42c, and vapor-phase etching is performed using hydrogen gas to remove the native oxide film formed on the surface of the silicon substrate 2.

[0032] Next, the drive unit 18 rotates the susceptor 13 and the silicon substrate 2 placed thereon, and while controlling the power of the lamps 41 and 42 so that the temperature of the silicon substrate 2 reaches a predetermined reaction temperature (for example, 1050 to 1180°C), a processing gas G is supplied from the gas supply port 19 to grow an epitaxial film 3 of a predetermined thickness in the vapor phase to obtain an epitaxial wafer 1.

[0033] Furthermore, a film thickness distribution in which the film thickness at the outer periphery is thinner than the film thickness A at the center, such as the epitaxial film 3 of the epitaxial wafer 1 of the present invention, can be obtained, for example, by adjusting the output of the lamps 41 and 42 of the epitaxial growth apparatus 11. For simplicity, here we will describe the case where the rows of lamps are arranged in two concentric rows, inner and outer, as shown in Figure 3. In other words, regarding the power ratio of lamp heating, "When the thin film thickness is consistent across the outer periphery, and you want to further reduce the film thickness in the outer periphery to less than 1 (with the film thickness in the center being 1)." Upper lamp 41: inside > outside, and, Lower lamp 42: Inside < Outside year, Upper lamp 41: The inner proportion is increased, Lower lamp 42: Increase the proportion of the inner part. This method allows for a thinner film thickness on the outer periphery.

[0034] "When the film thickness at the outer periphery is constant within a range of less than 1 (film thickness at the center = 1), and you want to make the outer periphery range even wider." Upper lamp 41: inside > outside, and, Lower lamp 42: Inside < Outside year, Upper lamp 41: The inner proportion is larger, and Lower lamp 42: Increases the proportion of the inner part. This allows for a wider area of ​​thin film thickness in the outer periphery.

[0035] Furthermore, even in the case of three rows (inner rows: 41a, 42a, middle row: 41b, 42b, outer rows: 41c, 42c) as shown in Figure 2, it is possible to treat only 41a and 42a as inner lamps and 41b, 42b, 41c, and 42c as outer lamps. The same settings can be applied appropriately for four or more rows.

[0036] As described above, by adjusting the relative magnitudes of the inner and outer lamp outputs, the film thickness ratio of the outer periphery to the center and the extent of the outer periphery can be adjusted. However, the specific output ratio will vary depending on the size of the device 11 and the silicon substrate 2 used. Furthermore, as can be seen from the correlation above, both the degree of thinness of the outer periphery film thickness and the degree of the extent of the outer periphery area change with the lamp output ratio. Therefore, when actually manufacturing the epitaxial wafer 1 of the present invention, the lamp output ratio should be appropriately set according to the desired conditions of the epitaxial film, while referring to the correlation above.

[0037] As an example, consider the case of vapor-phase growth of an epitaxial film 3 (silicon germanium film) on a 300 mm diameter silicon substrate 2 at 650°C using a CENTURA lamp manufactured by APPLIED MATERIALS (with two rows of lamps, an inner row and an outer row). When the outer perimeter is fixed within a range of 10 mm inward from the outer perimeter, To make the outer film thickness 0.95-0.98 when the central film thickness is 1, Upper lamp 41: Inner (51-60%) > Outer (49-40%), and, Lower lamp 42: Inner (26-30%) < Outer (75-70%) It is possible to do so, To make the film thickness on the outer edge 0.90 to 0.98, Upper lamp 41: Inner (61-75%) > Outer (39-25%), and, Lower lamp 42: Inner (31-34%) < Outer (71-66%) It is possible to do so, To make the film thickness on the outer edge 0.80 to 0.98, Upper lamp 41: Inner (76-80%) > Outer (24-20%), and, Lower lamp 42: Inner (35-38%) < Outer (65-60%) It can be done this way. [Examples]

[0038] The present invention will be described more specifically below with reference to examples and comparative examples, but the present invention is not limited to these examples. (Example 1) A silicon germanium epitaxial film was formed on a 300 mm diameter silicon substrate using an epitaxial growth apparatus (RP-CVD apparatus: CENTURA, manufactured by APPLIED MATERIALS) (with two rows of lamps, an inner row and an outer row) in a mixed gas atmosphere containing SiH2Cl2 and GeH4 as source gases. The film was deposited so that the thickness of the epitaxial film in the center was 30 nm and the thickness of the outer periphery (from the outer periphery to 10 mm inward) was 28.5-29.5 nm (ratio of outer periphery thickness to central thickness: 0.95-0.98). The defect density was 0.06 / cm³. 2 That's what happened. The thickness of the epitaxial film was measured using a spectroscopic ellipsometer (JAWoolam M2000). Defect density was measured using a Surfscan SP3 from KLA-Tencor.

[0039] (Example 2) For the epitaxial wafer to be evaluated, an epitaxial wafer was deposited under the same conditions as in Example 1, except that the film thickness in the center of the epitaxial film was 30 nm and the film thickness in the outer periphery (from the outer periphery to 10 mm inward) was 27.0-29.5 nm (film thickness ratio: 0.90-0.98). The defect density was 0.06 / cm³. 2 That's what happened.

[0040] (Example 3) For the epitaxial wafer to be evaluated, an epitaxial wafer was deposited under the same conditions as in Example 1, except that the film thickness in the center of the epitaxial film was 30 nm and the film thickness in the outer periphery (from the outer periphery to 10 mm inward) was 24.0-29.5 nm (film thickness ratio: 0.80-0.98). The defect density was 0.04 / cm³. 2 That's what happened.

[0041] (Example 4) For the epitaxial wafer to be evaluated, an epitaxial wafer was deposited under the same conditions as in Example 1, except that the film thickness in the center of the epitaxial film was 30 nm and the film thickness in the outer periphery (from the outer periphery to 20 mm inward) was 28.5-29.5 nm (film thickness ratio: 0.95-0.98). The defect density was 0.05 / cm³. 2 That's what happened.

[0042] (Example 5) For the epitaxial wafer to be evaluated, an epitaxial wafer was deposited under the same conditions as in Example 1, except that the film thickness in the center of the epitaxial film was 30 nm and the film thickness in the outer periphery (from the outer periphery to 5 mm inward) was 28.5-29.5 nm (film thickness ratio: 0.95-0.98). The defect density was 0.12 / cm³. 2 That's what happened.

[0043] (Comparative Example 1) For the epitaxial wafer to be evaluated, an epitaxial wafer was deposited under the same conditions as in Example 1, except that the film thickness in the center of the epitaxial film was 30 nm and the film thickness in the outer periphery (from the outer periphery to 5 mm inward) was 30.0-31.5 nm (film thickness ratio: 1-1.05). The defect density was 2.52 / cm³. 2 That's what happened.

[0044] (Comparative Example 2) For the epitaxial wafer to be evaluated, an epitaxial wafer was deposited under the same conditions as in Example 1, except that the film thickness in the center of the epitaxial film was 30 nm and the film thickness in the outer periphery (from the outer periphery to 10 mm inward) was 30.0-31.5 nm (film thickness ratio: 1-1.05). The defect density was 5.32 / cm³. 2 That's what happened.

[0045] (Comparative Example 3) For the epitaxial wafer to be evaluated, an epitaxial wafer was deposited under the same conditions as in Example 1, except that the film thickness in the center of the epitaxial film was 30 nm and the film thickness in the outer periphery (from the outer periphery to 20 mm inward) was 30.0-31.5 nm (film thickness ratio: 1-1.05). The defect density was 7.37 / cm³. 2 That's what happened.

[0046] Table 1 shows the film deposition conditions and measurement results for each example. That is, for each example, (1) Output ratio of inner lamp (Inner Power) and outer lamp (Outer Power) at the top side (2) Output ratio of inner lamp and outer lamp at the bottom (Bottom Side) (3) The ratio of the thickness of the outer periphery to the thickness of the central part (outer periphery thickness / central part thickness) (4) Outer periphery (5) Defect density This is shown. Note that Example 1 is described twice. Also, for (1) and (2), equality and inequality signs are included to make the relationship between the inner and outer lamps easier to understand.

[0047] Furthermore, Table 2 shows a different summary of (3) to (5). For (3), the film thickness value of the outer periphery itself is also shown. The values ​​enclosed in the thick border are the defect density for (5).

[0048] [Table 1]

[0049] [Table 2]

[0050] From Tables 1 and 2, the following relationships were confirmed, particularly regarding film thickness ratio, outer edge area, and defect density. First, we compared each example with each comparative example. Regarding the magnitude relationship of the output ratios between the inner lamp and the outer lamp, in each of the examples and comparative examples, in the lower lamp, all were "inner < outer", while in the upper lamp, in each of the examples, it was "inner > outer", whereas in Comparative Example 1, it was "inner = outer", and in Comparative Examples 2 and 3, it was "inner < outer". And the defect density was 0.04 to 0.12 / cm 2 whereas in each of the comparative examples, it was 2.52 to 7.37 / cm 2 It can be seen that adjusting the output ratio between the inner lamp and the outer lamp is effective in reducing the defect density.

[0051] Also, the examples were compared with each other. In Examples 5, 1, and 4 where the film thickness ratios were all the same (0.95 to 0.98) and the range of the outer peripheral part was 5 mm, 10 mm, and 20 mm, the defect densities were 0.12 / cm 2 , 0.06 / cm 2 , 0.05 / cm 2 respectively. A tendency was observed that the defect density decreased as the range of the outer peripheral part became wider. Note that in Examples 5, 1, and 4, where the upper lamp had "inner > outer" for the output ratio and the lower lamp had "inner < outer", a tendency was observed that as the output ratio of the inner lamp in the upper or lower part increased, the range of the outer peripheral part became wider.

[0052] In Examples 1, 2, and 3 where the range of the outer peripheral part was all the same (10 mm) and the film thickness ratios were 0.95 to 0.98, 0.90 to 0.98, and 0.80 to 0.98, the defect densities were 0.06 / cm 2 , 0.06 / cm 2 , 0.04 / cm 2 respectively. A tendency was observed that the defect density decreased as the film thickness ratio became smaller, that is, as the film thickness of the outer peripheral part became thinner compared to the film thickness of the central part. Note that in Examples 1, 2, and 3, where the upper lamp had "inner > outer" for the output ratio and the lower lamp had "inner < outer", a tendency was observed that as the output ratio of the inner lamp in the upper or lower part increased, the film thickness ratio became lower.

[0053] This specification includes the following aspects. [1]: An epitaxial wafer having an epitaxial film of a semiconductor material different from silicon formed on a silicon substrate, The epitaxial film is an epitaxial wafer in which the film thickness at the outer edge of the wafer is less than 1 when the film thickness at the center of the wafer is set to 1. [2]: The epitaxial wafer of [1], wherein the outer periphery of the wafer extends 5 mm inward from the outer periphery. [3]: The epitaxial wafer of [1], wherein the outer periphery of the wafer extends 10 mm inward from the outer periphery. [4]: The epitaxial wafer of [1], wherein the outer periphery of the wafer extends 20 mm inward from the outer periphery. [5]: The epitaxial film is an epitaxial wafer according to any of the above [1] to [4], wherein the film thickness at the outer periphery of the wafer is 0.95 or more and less than 1. [6]: The epitaxial film is an epitaxial wafer according to any of the above [1] to [4], wherein the film thickness at the outer periphery of the wafer is 0.9 or more and less than 1. [7]: The epitaxial film is an epitaxial wafer according to any of the above [1] to [4], wherein the film thickness at the outer edge of the wafer is 0.8 or more and less than 1. [8]: The epitaxial wafer according to any of [1] to [7] above, wherein the epitaxial film is one of a silicon germanium film, a germanium film, a silicon carbide film, and a gallium nitride film. [9]: The epitaxial wafer is any of the epitaxial wafers described in [1] to [8] above, having a diameter of 300 mm or more.

[0054] It should be noted that the present invention is not limited to the embodiments described above. The embodiments described above are illustrative, and any configuration that is substantially identical to the technical idea described in the claims of the present invention and achieves similar effects is included within the technical scope of the present invention. [Explanation of symbols]

[0055] 1...Epitaxial wafer of the present invention, 2...Silicon substrate, 3…Epitaxial film, 11…Epitaxial growth apparatus, 12…Chamber, 13…Susceptor 14... Counterbore, 15... Through hole, 16... Lift pin, 17... Shaft 18...Drive unit, 19...Gas supply port, 20...Gas outlet, 41 (41a~41c), 42 (42a~42c)... Lamp, A: Film thickness in the center, B: Film thickness in the outer periphery, L: Shaft axis, G: Processing gas.

Claims

1. An epitaxial wafer having an epitaxial film of a semiconductor material different from silicon formed on a silicon substrate, The epitaxial film has a thickness of 0.6 or more and less than 1 in the area from the outer edge of the wafer to 10 mm inward, when the thickness of the film at the center of the wafer is set to 1, and the thickness is thickest at the center of the wafer, with the thickness gradually decreasing towards the outer edge. The epitaxial wafer is characterized in that the epitaxial film is one of a silicon germanium film, a germanium film, or a silicon carbide film.

2. The epitaxial wafer according to Claim 1, characterized in that the epitaxial film has a film thickness of 0.6 or more and less than 1 in the area of ​​the outer edge of the wafer, from the outer edge to 20 mm inward.

3. The epitaxial wafer according to claim 1 or 2, characterized in that the epitaxial film has a film thickness of 0.95 or more and less than 1 at the outer periphery of the wafer.

4. The epitaxial wafer according to claim 1 or 2, characterized in that the epitaxial film has a film thickness of 0.9 or more and less than 1 at the outer periphery of the wafer.

5. The epitaxial wafer according to claim 1 or 2, characterized in that the epitaxial film has a film thickness of 0.8 or more and less than 1 at the outer periphery of the wafer.

6. The epitaxial wafer according to claim 1 or 2, characterized in that the epitaxial wafer has a diameter of 300 mm or more.

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