Bonded substrate, method for manufacturing bonded substrate, and method for manufacturing semiconductor device

Abstract

The present invention provides a technology that can prevent moisture from penetrating into a gap between the ends of two substrates. The bonded substrate includes an upper substrate having a first end, a lower substrate having a second end, and a deposit. The lower substrate is bonded to the upper substrate with a gap between the first end and the second end, and the deposit is connected to the first end and the second end. The surface roughness of the deposit is greater than the surface roughness of at least one of the upper surface of the upper substrate and the lower surface of the lower substrate.

Description

[Technical Field]

[0001] The present disclosure relates to a bonded substrate, a method for manufacturing a bonded substrate, and a method for manufacturing a semiconductor device. [Background technology]

[0002] Various techniques have been proposed for bonded substrates in which two substrates are bonded together. For example, Patent Document 1 proposes a technique for filling the gap between the edges of two substrates with a reinforcing material or the like. This technique can prevent the two bonded substrates from peeling off during the semiconductor manufacturing process, thereby improving the quality of semiconductor devices. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 5-304062 Summary of the Invention [Problem to be solved by the invention]

[0004] However, while conventional techniques can prevent large particles from penetrating from the outside to the inside of the reinforcing material, i.e., from the outside to the inside of the gap between the edges of two substrates, they may not be able to sufficiently prevent moisture adhering to the reinforcing material itself or the surfaces of the bonded substrates around the reinforcing material, such as from a cleaning process, from penetrating into the reinforcing material. As a result, contaminants contained in the remaining moisture may contaminate the bonded substrates themselves or the semiconductor manufacturing equipment that processes the bonded substrates.

[0005] Therefore, the present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a technology that can prevent moisture from entering the gap between the ends of two substrates. [Means for solving the problem]

[0006] The bonded substrate according to the present disclosure includes an upper substrate having a first end, a lower substrate having a second end and bonded to the upper substrate with a gap between the first end and the second end, and a deposit connected to the first end and the second end. an epitaxially grown layer formed on the upper substrate and made of the same material as the deposit; wherein the surface roughness of the deposit is greater than the surface roughness of at least one of the upper surface of the upper substrate and the lower surface of the lower substrate. [Effects of the Invention]

[0007] According to the present disclosure, the surface roughness of the deposit is greater than the surface roughness of at least one of the upper surface of the upper substrate and the lower surface of the lower substrate, and this configuration can prevent moisture from entering the gap between the ends of the two substrates.

[0008] The objects, features, aspects and advantages of the present disclosure will become more apparent from the following detailed description and the accompanying drawings. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view showing the configuration of a bonded substrate according to a first embodiment. [Figure 2] 3 is a flowchart showing a method for manufacturing the bonded substrate and the semiconductor device according to the first embodiment. [Figure 3] 10 is a cross-sectional view showing a configuration of a bonded substrate according to a first modification of the first embodiment. FIG. [Figure 4] 10 is a cross-sectional view showing a configuration of a bonded substrate according to a first modification of the first embodiment. FIG. [Figure 5] 10 is a cross-sectional view showing a configuration of a bonded substrate according to a second modification of the first embodiment. FIG. [Figure 6] 10 is a cross-sectional view showing a configuration of a bonded substrate according to a second modification of the first embodiment. FIG. [Figure 7] 10 is a cross-sectional view showing a configuration of a bonded substrate according to a second modification of the first embodiment. FIG. [Figure 8] FIG. 10 is a cross-sectional view showing a configuration of a bonded substrate according to a third modification of the first embodiment. [Figure 9]FIG. 10 is a cross-sectional view showing a configuration of a bonded substrate according to a third modification of the first embodiment. [Figure 10] FIG. 10 is a cross-sectional view showing the configuration of a bonded substrate according to a second embodiment. [Figure 11] 10 is a flowchart showing a method for manufacturing a bonded substrate and a semiconductor device according to a second embodiment. [Figure 12] FIG. 10 is a cross-sectional view showing a configuration of a bonded substrate according to a modified example of the second embodiment. [Figure 13] FIG. 10 is a cross-sectional view showing the structure of a bonded substrate according to a third embodiment. [Figure 14] FIG. 10 is a plan view showing the configuration of a bonded substrate according to a third embodiment. [Figure 15] FIG. 11 is a cross-sectional view showing a configuration of a bonded substrate according to a modified example of the third embodiment. [Figure 16] FIG. 11 is a cross-sectional view showing a configuration of a bonded substrate according to a modified example of the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments will be described with reference to the accompanying drawings. Features described in each of the following embodiments are exemplary, and not all features are necessarily required. In addition, in the following description, similar components in multiple embodiments are denoted by the same or similar reference numerals, and different components will be mainly described. In addition, in the following description, specific positions and directions such as "upper," "lower," "left," "right," "front," or "back" may not necessarily correspond to positions and directions in actual implementation.

[0011] <First Embodiment> 1 is a cross-sectional view showing the structure of the bonded substrate according to the present embodiment 1. The bonded substrate of FIG.

[0012] The upper substrate 1 has a first end portion 1a and an upper surface 1b, and the first end portion 1a has a first upper surface 1c, a first end surface 1d, and a first lower surface 1e. For convenience, the upper surface 1b and the first upper surface 1c are distinguished below, but the upper surface 1b may include the first upper surface 1c. In a cross-sectional view, the first lower surface 1e is inclined toward the center of the first end portion 1a, and the first upper surface 1c is inclined toward the center of the first end portion 1a.

[0013] The lower substrate 2 has a second end portion 2a and a lower surface 2b, and the second end portion 2a has a second upper surface 2c, a second end surface 2d, and a second lower surface 2e. For convenience, the lower surface 2b and the second lower surface 2e are distinguished below, but the lower surface 2b may include the second lower surface 2e. In a cross-sectional view, the second lower surface 2e is inclined toward the center of the second end portion 2a, and the second upper surface 2c is not inclined toward the center of the second end portion 2a.

[0014] The upper substrate 1 and the lower substrate 2 are joined together with a gap 4 between the first end 1a and the second end 2a. In the example of Fig. 1, the gap 4 is provided between the first lower surface 1e of the first end 1a and the second upper surface 2c of the second end 2a.

[0015] The thickness of each of the upper substrate 1 and the lower substrate 2 is, for example, not less than 50 μm and not more than 500 μm. At least one of the upper substrate 1 and the lower substrate 2 is made of, for example, single-crystal silicon carbide (SiC). Note that at least one of the upper substrate 1 and the lower substrate 2 may be made of a wide bandgap semiconductor other than silicon carbide, such as gallium nitride (GaN), gallium oxide (Ga2O3), or diamond.

[0016] Generally, substrates using wide bandgap semiconductors are expensive, and using a single thin substrate in semiconductor manufacturing can result in mechanical deformation, damage, and other defects, which can significantly affect the production cost of semiconductor devices. Furthermore, the number of substrates using wide bandgap semiconductors that can be obtained is limited depending on the required specifications, which can result in a shortage of semiconductor device production compared to the planned number. The bonding technology disclosed herein can appropriately set the thickness of the bonded substrate while suppressing moisture penetration into the gap 4, thereby reducing the production cost of semiconductor devices using wide bandgap semiconductor substrates and ensuring production volume.

[0017] A semiconductor device formed by performing a semiconductor manufacturing process on a junction substrate of wide bandgap semiconductors can operate stably at high temperatures and high voltages and achieve high switching speeds. The semiconductor device includes, for example, at least one of a metal oxide semiconductor field effect transistor (MOSFET), an insulated gate bipolar transistor (IGBT), a reverse conducting IGBT (RC-IGBT), a Schottky barrier diode (SBD), and a PN junction diode (PND). In this specification, for example, "at least one of A, B, C, ..., and Z" means any one of all combinations of one or more elements selected from the group A, B, C, ..., and Z.

[0018] The deposit 3 is connected to the first end 1a and the second end 2a. In the first embodiment, the deposit 3 includes a first connection portion 3a connecting the first end surface 1d and the second end surface 2d, and a second connection portion 3b connecting the first lower surface 1e and the second upper surface 2c. The second connection portion 3b in FIG. 1 is provided except for the deepest portion of the gap 4.

[0019] The surface roughness of the deposit 3 is greater than the surface roughness of at least one of the upper surface 1b of the upper substrate 1 and the lower surface 2b of the lower substrate 2. From the viewpoint of water repellency, the surface roughness (Ra) of the deposit 3 may be greater than that of a mirror-polished surface, e.g., Ra≧2 nm. Preferably, Ra≧10 nm, and more preferably, Ra≧100 nm. This can be achieved by forming the deposit 3 in the gap 4 even when at least one of the upper substrate 1 and the lower substrate 2 is made of single-crystal silicon carbide and the material of the deposit 3 contains single-crystal silicon carbide, polycrystalline silicon carbide, or carbon. When the material of the deposit 3 contains single-crystal silicon carbide, polycrystalline silicon carbide, or carbon, the deposit 3 can easily withstand high-temperature processes of around 1000°C in semiconductor manufacturing processes. The material of the deposit 3 may also contain materials other than those mentioned above, such as oxides such as silicon oxide, or amorphous materials.

[0020] As described above, the surface roughness of the deposit 3 is greater than the surface roughness of at least one of the upper surface 1b of the upper substrate 1 and the lower surface 2b of the lower substrate 2, thereby making the water repellency of the deposit 3 higher than that of at least one of the first upper surface 1c and the second lower surface 2e. The water repellency of the deposit 3 may also be greater than that of at least one of the first end surface 1d and the second end surface 2d. When the surface roughness of the first end surface 1a or the second end surface 2a, which is the periphery of the deposit 3, is greater than the surface roughness of at least one of the upper surface 1b of the upper substrate 1 and the lower surface 2b of the lower substrate 2, adhesion of moisture to the periphery of the deposit 3 can be suppressed. This prevents moisture adhering to and remaining on the periphery of the deposit 3 from penetrating into the gap 4 via the moisture penetration path in the deposit 3, even if there are small moisture penetration paths such as micropores in the deposit 3.

[0021] <Manufacturing method> FIG. 2 is a flowchart showing a method for manufacturing a bonded substrate according to the first embodiment and a method for manufacturing a semiconductor device using the bonded substrate.

[0022] In step S1, an upper substrate 1 and a lower substrate 2 are prepared. In step S2, the upper substrate 1 and the lower substrate 2 are bonded to each other with a gap 4 between the first end 1a and the second end 2a. For bonding, room temperature bonding is used, for example. Note that, in order to increase the strength of the room temperature bonding, CMP (Chemical Mechanical Polishing) processing may be performed on the bonding surfaces of the upper substrate 1 and the lower substrate 2 before the room temperature bonding.

[0023] In step S3, a deposit 3 connected to the first end 1 a and the second end 2 a is formed. For example, a resist is formed that exposes only the area of ​​the joined upper substrate 1 and lower substrate 2 where the deposit 3 is to be formed, and the deposit 3 may be formed by performing sputtering, vapor deposition, or crystal growth on that area.

[0024] In step S4, predetermined semiconductor manufacturing processes for forming a semiconductor device are performed on the upper substrate 1. The predetermined semiconductor manufacturing processes include, for example, a process for forming an impurity region and a process for forming various layers (various films) such as by epitaxial growth.

[0025] In step S5, after the semiconductor manufacturing process of step S4, a portion is separated from the upper substrate 1 and the lower substrate 2. The separated portion may be a portion of the upper substrate 1 and the entire lower substrate 2, or may be at least a portion of the lower substrate 2, and will be used as the upper substrate 1 or the lower substrate 2 in the next manufacturing process. For example, laser slicing technology is used for the separation.

[0026] In the above description, the deposit 3 is formed on the first end 1 a and the second end 2 a using resist in step S3, but this is not limiting. For example, after the deposit 3 is formed on the entire upper substrate 1 and the lower substrate 2 after bonding in step S3, the deposit 3 on the upper surface 1 b of the upper substrate 1 and the lower surface 2 b of the lower substrate 2 may be removed by polishing.

[0027] <Summary of the First Embodiment> The bonded substrate according to the first embodiment as described above includes a deposit 3 connected to the first end 1a and the second end 2a. The surface roughness of the deposit 3 is greater than the surface roughness of at least one of the upper surface 1b of the upper substrate 1 and the lower surface 2b of the lower substrate 2, and therefore the water repellency of the deposit 3 is greater than that of at least one of the upper surface 1b of the upper substrate 1 and the lower surface 2b of the lower substrate 2. This configuration can prevent moisture, which is a foreign substance, from entering the gap 4 between the first end 1a and the second end 2a, thereby improving the quality of the semiconductor device.

[0028] In the first embodiment, the deposit 3 includes a first connection portion 3a connecting the first end face 1d and the second end face 2d and a second connection portion 3b connecting the first lower face 1e and the second upper face 2c. This configuration can more effectively prevent moisture from entering the gap 4 than a configuration in which the deposit 3 includes only one of the first connection portion 3a and the second connection portion 3b.

[0029] Furthermore, in this embodiment 1, the second connection portion 3b is provided except for the deepest portion of the gap 4, that is, except for the portion that is relatively difficult to fill in practically, so that a bonded substrate can be realized by a realistic deposit 3.

[0030] Furthermore, in the first embodiment, portions are separated from the upper substrate 1 and the lower substrate 2 after the semiconductor manufacturing process. This configuration allows the separated portions to be reused as the upper substrate 1 or the lower substrate 2 in the next manufacturing process. For example, a semiconductor device is manufactured by separating part or all of the upper substrate 1 on which semiconductor elements have been formed through the semiconductor manufacturing process, and then collecting multiple substrates whose remaining portions have been flattened by polishing or the like for reuse. These substrates are then bonded together to form the deposit 3, allowing the semiconductor manufacturing process to be restarted. This improves substrate utilization efficiency and reduces production costs. This is particularly effective in reducing production costs when using expensive substrates such as wide-gap semiconductor substrates. The separation and reuse of the substrates may be repeated multiple times.

[0031] <Variation 1> 3 and 4 are cross-sectional views showing variations of the shape of the deposit 3 in first to fourteenth examples. The shape of the deposit 3 in the first example is the same as the shape of the deposit 3 in Fig. 1. Note that some reference numerals are omitted in Fig. 3 and Fig. 4.

[0032] The deposit 3 in the first to seventh examples includes a first connection portion 3a connecting the first end surface 1d and the second end surface 2d, and a second connection portion 3b connecting the first lower surface 1e and the second upper surface 2c. In the first example, the right side surface of the first connection portion 3a in FIG. 3 is flat. In the second example, the right side surface of the first connection portion 3a in FIG. 3 is a curved surface that bulges in the center. In the third example, a recess corresponding to the gap 4 is provided on the right side surface of the first connection portion 3a in FIG. 3.

[0033] In the fourth and fifth examples, the gap 4 in the first and second examples is completely or substantially filled by the second connecting portion 3b. In the sixth example, the first connecting portion 3a is connected to the corner 2f between the second upper surface 2c and the second end surface 2d in the first example. In the seventh example, the first connecting portion 3a is connected to the corner 1f between the first lower surface 1e and the first end surface 1d in the first example.

[0034] The deposits 3 in Examples 8 to 11 in Fig. 4 include the first connection portion 3a but not the second connection portion 3b. In Examples 8, 9, 10, and 11, the second connection portion 3b is omitted from Examples 1, 2, 6, and 7.

[0035] The deposits 3 in Examples 12 to 14 do not include the first connection portion 3a but include the second connection portion 3b. In Example 12, the gap 4 is completely or substantially filled with the second connection portion 3b. In Example 13, the second connection portion 3b is provided except for the deepest portion of the gap 4. In Example 14, the second connection portion 3b is provided only in the deepest portion of the gap 4.

[0036] Even with the deposit 3 as described above, it is possible to obtain the same effects as in embodiment 1. However, the shape of the deposit 3 is not limited to the above shape.

[0037] <Variation 2> 5 to 7 are cross-sectional views showing 21st to 38th examples of variations in the shapes of the upper substrate 1 and the lower substrate 2. Note that some reference numerals are omitted in FIGS.

[0038] 1, in a cross-sectional view of the upper substrate 1, the first lower surface 1e is inclined toward the center of the first end portion 1a, and the first upper surface 1c is inclined toward the center of the first end portion 1a. In a cross-sectional view of the lower substrate 2, the second lower surface 2e is inclined toward the center of the second end portion 2a, and the second upper surface 2c is not inclined toward the center of the second end portion 2a.

[0039] In contrast, the shape of the lower substrate 2 in Examples 21 to 26 of FIG. 5 is similar to the shape of the lower substrate 2 in FIG. 1, but the shape of the upper substrate 1 in Examples 21 to 26 of FIG. 5 is different from the shape of the upper substrate 1 in FIG. 1. In a cross-sectional view of the upper substrate 1 in Examples 21 to 26, the first lower surface 1e is inclined toward the center of the first end portion 1a, and the first upper surface 1c is not inclined toward the center of the first end portion 1a. The shapes of the deposits 3 in Examples 21, 22, 23, 24, 25, and 26 of FIG. 5 are similar to the shapes of the deposits 3 in Examples 1, 4, 8, 12, 13, and 14 of FIGS. 3 and 4.

[0040] The shape of the upper substrate 1 in Examples 27 to 32 of FIG. 6 is similar to the shape of the upper substrate 1 in FIG. 1, but the shape of the lower substrate 2 in Examples 27 to 32 of FIG. 6 is different from the shape of the lower substrate 2 in FIG. 1. In a cross-sectional view of the lower substrate 2 in Examples 27 to 32, the second lower surface 2e is inclined toward the center of the second end 2a, and the second upper surface 2c is inclined toward the center of the second end 2a. The shape of the deposit 3 in Examples 27 to 32 of FIG. 6 is similar to the shape of the deposit 3 in Examples 21 to 26 of FIG. 5.

[0041] The shapes of the upper substrate 1 in the 33rd to 38th examples in Fig. 7 are similar to the shapes of the upper substrate 1 in the 21st to 26th examples in Fig. 5, and the shapes of the lower substrate 2 in the 33rd to 38th examples in Fig. 6 are similar to the shapes of the lower substrate 2 in the 27th to 32nd examples. The shapes of the deposits 3 in the 33rd to 38th examples in Fig. 7 are similar to the shapes of the deposits 3 in the 21st to 26th examples in Fig. 5.

[0042] Even with the upper substrate 1 and lower substrate 2 as described above, the same effects as in the first embodiment can be obtained. In other words, instead of substrates with a specific cross-sectional shape, substrates with various cross-sectional shapes can be used for the upper substrate 1 and the lower substrate 2, thereby improving the productivity of bonded substrates. Note that the shapes of the upper substrate 1, lower substrate 2, and deposit 3 are not limited to those described above.

[0043] <Variation 3> 8 and 9 are cross-sectional views showing 41st to 54th examples of variations in the shapes of the upper substrate 1 and the lower substrate 2. Note that some reference numerals are omitted in FIGS.

[0044] The shape of the upper substrate 1 in the 41st to 54th examples in Figures 8 and 9 is similar to the shape of the upper substrate 1 in Figure 1, but the shape of the lower substrate 2 in the 41st to 54th examples in Figures 8 and 9 is different from the shape of the lower substrate 2 in Figure 1. In a cross-sectional view of the lower substrate 2 in the 41st to 54th examples, a step 2g is provided on the second end face 2d on the gap 4 side of the second end 2a. The shape of the deposit 3 in the 41st to 54th examples is similar to the shape of the deposit 3 in the 1st to 14th examples.

[0045] With the upper substrate 1 and lower substrate 2 as described above, the gap 4 can be made larger, and therefore the deposit 3 can be easily formed inside the gap 4. The shape of the upper substrate 1 does not have to be the same as the shape of the upper substrate 1 in Fig. 1, and may be the same as the shapes of the upper substrate 1 in the 21st to 26th examples in Fig. 5, for example.

[0046] <Embodiment 2> 10 is a cross-sectional view showing the structure of a bonded substrate according to the present embodiment 2. The present embodiment 2 has the same structure as that shown in FIG.

[0047] The epitaxial growth layer 5 is provided on the upper substrate 1 and is made of the same material as the deposit 3. In the example of Fig. 10, the epitaxial growth layer 5 is integrally connected to the deposit 3, but the deposit 3 and the epitaxial growth layer 5 may be separated by etching or the like.

[0048] Fig. 11 is a flowchart showing a method for manufacturing a bonded substrate and a method for manufacturing a semiconductor device using the bonded substrate according to the second embodiment. The manufacturing method in Fig. 11 is the same as the manufacturing method in Fig. 2 except that step S3 is replaced by step S3a, so the following description will mainly focus on step S3a.

[0049] In step S3a, an epitaxial growth layer 5 is formed on the upper substrate 1 by, for example, CVD (Chemical Vapor Deposition), while a portion of the material of the epitaxial growth layer 5 that has spread between the first end 1a and the second end 2a forms a deposit 3. The outer surfaces of the upper substrate 1 and the lower substrate 2 may be RCA cleaned before being placed in the CVD apparatus, or may be H2 etched within the CVD apparatus. The process conditions for the CVD film including the deposit 3 and the epitaxial growth layer 5 are, for example, a growth temperature of 1550 to 1700°C and a carbon gas to silicon gas ratio of 1.2 to 1.8.

[0050] <Summary of the second embodiment> According to the second embodiment described above, the epitaxial growth layer 5 is provided on the upper substrate 1 and is made of the same material as the deposit 3. With this configuration, the deposit 3 can be formed while the epitaxial growth layer 5 included in the semiconductor device is being formed, thereby simplifying the process. Furthermore, the dense deposit 3 formed by epitaxial growth can block any path for moisture to penetrate, even if it is only a small amount, so that the penetration of moisture into the gap 4 can be effectively suppressed.

[0051] <Modification> 12, epitaxially grown layer 5 may include, as multiple semiconductor layers with different process conditions, a buffer layer 5a provided on upper substrate 1 and a drift layer 5b provided on buffer layer 5a. With this configuration, deposit 3 including portion 3c formed in parallel with buffer layer 5a and portion 3d formed in parallel with drift layer 5b can be easily provided in gap 4.

[0052] The process conditions for the buffer layer 5a are, for example, a growth temperature of 1550 to 1700°C and a carbon gas to silicon gas ratio of 0.8 to 1.4. Forming the buffer layer under these conditions promotes penetration of the material of the epitaxial growth layer 5 into the gap 4 between the first end 1a and the second end 2a, improving the embedding of the deposit. The process conditions for the drift layer 5b are, for example, a growth temperature of 1550 to 1700°C and a carbon gas to silicon gas ratio of 1.2 to 1.8.

[0053] <Third Embodiment> FIG. 13 is a cross-sectional view showing the structure of a bonded substrate according to the third embodiment. In this third embodiment, the lower substrate 2 protrudes outward in the in-plane direction of the lower substrate 2 relative to the upper substrate 1. The shape of the first end 1a of the upper substrate 1 is not limited to the shape shown in FIG. 13 and may be a rectangle with substantially no slopes. In this case, the gap 4 is formed in the region where the first lower surface 1e and the second upper surface 2c face each other and are not bonded. This configuration may be achieved by having the diameter of the lower substrate 2 larger than the diameter of the upper substrate 1, as shown in the plan view of FIG. 14. Alternatively, it may be achieved by having the upper substrate 1 and the lower substrate 2 be offset from the upper substrate 1 when their diameters are the same. Here, when the lower substrate 2 is bonded offset from the upper substrate 1, one end of the bonded substrate has the shape shown in FIG. 13, but the other end of the lower substrate 1 protrudes outward relative to the upper substrate 2. Even in such other end portions, the first end 1a and the second end 2a can be connected by a deposit 3, as shown in FIG. 16, which will be described later. In FIG. 14, the deposit 3 is omitted from the illustration.

[0054] <Summary of the Third Embodiment> According to the above-described third embodiment, the lower substrate 2 protrudes further outward in the in-plane direction of the lower substrate 2 than the upper substrate 1, so that the deposit 3 can be easily provided in the gap 4, and in particular, the gap 4 can be easily made smaller.

[0055] <Modification> 15 and 16 are cross-sectional views showing variations of Examples 61 to 72 regarding the positional relationship between the upper substrate 1 and the lower substrate 2. The positional relationship between the upper substrate 1 and the lower substrate 2 in Example 61 is the same as the positional relationship between the upper substrate 1 and the lower substrate 2 in Figure 13. Note that some reference numerals are omitted in Figures 15 and 16.

[0056] In the 61st to 66th examples of Fig. 15, the lower substrate 2 protrudes outward in the in-plane direction of the lower substrate 2 more than the upper substrate 1. The shapes of the deposits 3 in the 61st, 62nd, 64th, 65th, and 66th examples of Fig. 15 are similar to the shapes of the deposits 3 in the 1st, 4th, 12th, 13th, and 14th examples of Fig. 3 and Fig. 4. The deposit 3 in the 63rd example of Fig. 15 includes a second connection portion 3b provided in the back portion of the gap 4 and a portion 3e provided on the second upper surface 2c and the second end surface 2d.

[0057] In the 67th to 72nd examples of Fig. 16, the upper substrate 1 protrudes outward in the in-plane direction of the upper substrate 1 more than the lower substrate 2. The shapes of the deposits 3 in the 67th, 68th, 70th, 71st, and 72nd examples of Fig. 16 are similar to the shapes of the deposits 3 in the 61st, 62nd, 64th, 65th, and 66th examples of Fig. 15. The deposit 3 in the 69th example of Fig. 16 includes a second connection portion 3b provided in the back portion of the gap 4 and a portion 3f provided on the first end surface 1d and the first lower surface 1e.

[0058] According to the above-described modified example, either the end of the upper substrate 1 or the lower substrate 2 can be protruded outward, so that the upper substrate 1 and the lower substrate 2 can be combined and joined without limiting the diameters of the substrates used for joining, thereby improving the flexibility of production. Furthermore, even with the above-described upper substrate 1 and lower substrate 2, the same effects as those of the third embodiment can be obtained.

[0059] It should be noted that the embodiments and modifications may be freely combined, and the embodiments and modifications may be modified or omitted as appropriate.

[0060] The above description is illustrative in all respects and is not restrictive. It is understood that countless variations not illustrated can be envisioned. [Explanation of symbols]

[0061] 1 upper substrate, 1a first end, 1b upper surface, 1c first upper surface, 1d first end surface, 1e first lower surface, 2 lower substrate, 2a second end, 2b lower surface, 2c second upper surface, 2d second end surface, 2e second lower surface, 2g step, 3 deposit, 3a first connection part, 3b second connection part, 4 gap, 5 Epitaxial growth layer, 5a buffer layer, 5b drift layer.

Claims

1. an upper substrate having a first end; a lower substrate having a second end and joined to the upper substrate with a gap between the first end and the second end; a deposit connected to the first end and the second end; an epitaxially grown layer formed on the upper substrate and made of the same material as the deposit; Equipped with A bonded substrate, wherein the surface roughness of the deposit is greater than the surface roughness of at least one of the upper surface of the upper substrate and the lower surface of the lower substrate.

2. an upper substrate having a first end; a lower substrate having a second end and joined to the upper substrate with a gap between the first end and the second end; a deposit connected to the first end and the second end; Equipped with a surface roughness of the deposit is greater than a surface roughness of at least one of an upper surface of the upper substrate and a lower surface of the lower substrate; a material of at least one of the upper substrate and the lower substrate is single-crystal silicon carbide; A bonded substrate, wherein the material of the deposit contains any one of single crystal silicon carbide, polycrystalline silicon carbide, and carbon.

3. an upper substrate having a first end; a lower substrate having a second end and joined to the upper substrate with a gap between the first end and the second end; a deposit connected to the first end and the second end; Equipped with a surface roughness of the deposit is greater than a surface roughness of at least one of an upper surface of the upper substrate and a lower surface of the lower substrate; one of the upper substrate and the lower substrate protrudes outward in an in-plane direction beyond the other of the upper substrate and the lower substrate; A bonded substrate, wherein the diameter of the one of the upper substrate and the lower substrate is larger than the diameter of the other of the upper substrate and the lower substrate.

4. The bonded substrate according to any one of claims 1 to 3, The deposit is a first connection portion connecting a first end surface of the first end portion and a second end surface of the second end portion; a second connection portion connecting a first lower surface of the first end portion and a second upper surface of the second end portion.

5. The bonded substrate according to claim 4, The deposit includes the first connection portion and the second connection portion.

6. The bonded substrate according to claim 5, The second connection portion is provided in the gap except for a deep portion of the gap.

7. The bonded substrate according to any one of claims 1 to 3, In a cross-sectional view, a first lower surface of the first end portion is inclined toward a center of the first end portion, and a first upper surface of the first end portion is inclined or not inclined toward a center of the first end portion, A bonded substrate, wherein, in a cross-sectional view, a second lower surface of the second end portion is inclined toward a center of the second end portion, and a second upper surface of the second end portion is either inclined toward a center of the second end portion or not inclined.

8. The bonded substrate according to any one of claims 1 to 3, In a cross-sectional view, a first lower surface of the first end portion is inclined toward a center of the first end portion, and a first upper surface of the first end portion is inclined or not inclined toward a center of the first end portion, A bonded substrate, wherein a step is provided on a second end surface of the second end portion on the gap side in a cross-sectional view.

9. an upper substrate having a first end and a lower substrate having a second end are joined together with a gap between the first end and the second end; forming a deposit connected to the first end and the second end; forming the deposit on the upper substrate while forming an epitaxially grown layer of the same material as the deposit; The method for manufacturing a bonded substrate, wherein the surface roughness of the deposit is greater than the surface roughness of at least one of the upper surface of the upper substrate and the lower surface of the lower substrate.

10. an upper substrate having a first end and a lower substrate having a second end are joined together with a gap between the first end and the second end; forming a deposit connected to the first end and the second end; a surface roughness of the deposit is greater than a surface roughness of at least one of an upper surface of the upper substrate and a lower surface of the lower substrate; a material of at least one of the upper substrate and the lower substrate is single-crystal silicon carbide; The method for manufacturing a bonded substrate, wherein the material of the deposit contains any one of single crystal silicon carbide, polycrystalline silicon carbide, and carbon.

11. an upper substrate having a first end and a lower substrate having a second end are joined together with a gap between the first end and the second end; forming a deposit connected to the first end and the second end; a surface roughness of the deposit is greater than a surface roughness of at least one of an upper surface of the upper substrate and a lower surface of the lower substrate; one of the upper substrate and the lower substrate protrudes outward in an in-plane direction beyond the other of the upper substrate and the lower substrate; A method for manufacturing bonded substrates, wherein the diameter of one of the upper substrate and the lower substrate is larger than the diameter of the other of the upper substrate and the lower substrate.

12. The method for manufacturing a bonded substrate according to claim 9, The epitaxially grown layer includes a plurality of semiconductor layers having different process conditions.

13. A method for manufacturing a bonded substrate according to any one of claims 9 to 11, comprising: The deposit is a first connection portion connecting a first end surface of the first end portion and a second end surface of the second end portion; and a second connection portion connecting a first lower surface of the first end portion and a second upper surface of the second end portion.

14. The method for manufacturing a bonded substrate according to claim 13, The method for manufacturing a bonded substrate, wherein the deposit includes the first connection portion and the second connection portion.

15. The method for manufacturing a bonded substrate according to claim 14, The method for manufacturing a bonded substrate, wherein the second connection portion is provided excluding a deep portion of the gap.

16. A method for manufacturing a bonded substrate according to any one of claims 9 to 11, comprising: In a cross-sectional view, a first lower surface of the first end portion is inclined toward a center of the first end portion, and a first upper surface of the first end portion is inclined or not inclined toward a center of the first end portion, a second lower surface of the second end portion inclined toward a center of the second end portion, and a second upper surface of the second end portion inclined or not inclined toward a center of the second end portion, when viewed in cross section.

17. A method for manufacturing a bonded substrate according to any one of claims 9 to 11, comprising: In a cross-sectional view, a first lower surface of the first end portion is inclined toward a center of the first end portion, and a first upper surface of the first end portion is inclined or not inclined toward a center of the first end portion, A method for manufacturing a bonded substrate, wherein a step is provided on a second end surface of the second end portion on the gap side in a cross-sectional view.

18. A method for manufacturing a semiconductor device using the method for manufacturing a bonded substrate according to any one of claims 9 to 11, performing a predetermined semiconductor manufacturing process on the upper substrate after forming the deposit; A method for manufacturing a semiconductor device, wherein a portion is separated from the upper substrate and the lower substrate after the semiconductor manufacturing process.

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