Substrate for electronic device and method for producing same

Abstract

To provide an electronic device substrate including a nitride semiconductor formed on a silicon single crystal, capable of suppressing the occurrence of a slip, a crack and the like and high in breaking strength, and a method for manufacturing the same.SOLUTION: An electronic device substrate includes a nitride semiconductor film formed on a silicon single crystal bonded substrate. The bonded substrate is obtained by bonding a first silicon single crystal substrate having a crystal plane orientation of {111} and a second silicon single crystal substrate having a crystal plane orientation of {100} through an oxide film; the first substrate has a notch in a<110>direction; the second substrate has a notch in a<011>or<001>direction; the<110>direction of the first substrate and the<011>direction of the second substrate are connected in an angle range of -15° to 15°; and the nitride semiconductor film is formed on the surface of the first substrate of the bonded substrate.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a substrate for an electronic device and a manufacturing method thereof, and more particularly to a substrate for an electronic device in which a nitride semiconductor is formed on a silicon substrate and a manufacturing method thereof. [Background technology]

[0002] Nitride semiconductors such as GaN and AlN can be used to fabricate high electron mobility transistors (HEMTs) and high-voltage electronic devices that use two-dimensional electron gas.

[0003] It is difficult to produce nitride semiconductor wafers by growing these nitride semiconductors on a substrate, and sapphire and SiC substrates have been used as growth substrates in the past. However, epitaxial growth of nitride semiconductors by vapor growth on silicon single crystal substrates has also been performed to increase the diameter of the substrate (larger aperture) and to reduce the cost of the substrate. The fabrication of epitaxially grown films of nitride semiconductors by vapor growth on silicon single crystal substrates is advantageous in that larger diameter substrates can be used than sapphire and SiC substrates, and therefore device productivity is high and processing is easy. However, in the vapor growth of nitride semiconductors on silicon single crystal substrates, stress due to differences in lattice constants and thermal expansion coefficients is likely to increase warping, slippage, cracking, etc., and therefore stress reduction is being performed by adjusting growth conditions and using a relaxation layer.

[0004] In particular, in order to make the epitaxial substrate for power devices high voltage resistant, it is necessary to produce GaN on Si (GaN on silicon single crystal) with a thicker epitaxial layer of GaN. To thicken the epitaxial layer, the silicon single crystal substrate, which is the growth substrate, may be thickened and epitaxial growth may be performed. As a method for thickening the silicon single crystal substrate, two silicon single crystal substrates are bonded together. Patent Document 1 discloses that the thickness of the bonded substrate is 2 mm or more. Patent Document 2 discloses a combination of two substrates to be bonded together, in which the bond wafer has a {111} orientation and a resistivity of 1 kΩcm or more, and the base wafer has a {100} orientation and a resistivity of 0.1 Ωcm or less. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2021-014376 A [Patent Document 2] Patent Publication No. 2021-027186 Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, it is known to use bonded substrates as growth substrates, as disclosed in Patent Documents 1 and 2. However, even when these bonded substrates are used, it is not possible to completely prevent the increase in warping and the occurrence of slips, cracks, etc. Furthermore, slips, cracks, etc. often occur mainly at the notch portion of the {111} silicon single crystal substrate that is epitaxially grown. Generally, {111} silicon single crystal substrates have <110> The {100} silicon single crystal substrate has a notch in the direction <011> Direction or <001> It is formed in the direction.

[0007] The present invention has been made to solve the above-mentioned problems, and has an object to provide a substrate for an electronic device in which a nitride semiconductor is formed on a silicon single crystal, the substrate having high fracture strength in which the occurrence of slippage, cracking, etc. is suppressed, and a method for manufacturing the same. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides a substrate for an electronic device in which a nitride semiconductor film is formed on a bonded substrate of silicon single crystal, the bonded substrate being a substrate in which a first silicon single crystal substrate having a crystal plane orientation of {111} and a second silicon single crystal substrate having a crystal plane orientation of {100} are bonded together via an oxide film, the first silicon single crystal substrate being: <110> The second silicon single crystal substrate has a notch formed in the direction of the <011> Direction or <001> A notch is formed in the first silicon single crystal substrate in the direction <110> and the second silicon single crystal substrate. <011> The present invention provides a substrate for electronic devices, characterized in that the nitride semiconductor film is formed on a surface of the first silicon single crystal substrate of the bonded substrate, the first silicon single crystal substrate being bonded at an angle ranging from -15° to 15°.

[0009] With such an electronic device substrate, the positional relationship between the cleavage planes of the first silicon single crystal substrate and the second silicon single crystal substrate can provide an electronic device substrate with high fracture strength in which the occurrence of slippage, cracking, and the like is suppressed.

[0010] In this case, the diameter of the bonded substrate may be 300 mm or more.

[0011] Thus, the substrate with high fracture strength of the present invention is particularly effective as a substrate for large-diameter electronic devices, such as a substrate having a diameter of 300 mm or more.

[0012] The present invention also provides a method for manufacturing a substrate for an electronic device, comprising forming a nitride semiconductor film on a bonded substrate of silicon single crystal, the method comprising the steps of: <110> a first silicon single crystal substrate having a crystal plane orientation of {111} and a notch formed in the {111} direction; <011> Direction or <001> The present invention includes a step of preparing a second silicon single crystal substrate having a crystal plane orientation of {100} and a notch formed in the {100} direction; a step of thermally oxidizing at least one of the first silicon single crystal substrate and the second silicon single crystal substrate to form an oxide film on the surface; <110> and the second silicon single crystal substrate. <011> The present invention provides a method for manufacturing a substrate for an electronic device, comprising the steps of: bonding the first silicon single crystal substrate and the second silicon single crystal substrate to each other by overlapping them via the oxide film so that the direction is in an angle range of -15° to 15° and performing a heat treatment to produce the bonded substrate; and epitaxially growing the nitride semiconductor film on a surface of the first silicon single crystal substrate of the bonded substrate.

[0013] With such a method for manufacturing a substrate for an electronic device, it is possible to manufacture a substrate for an electronic device having high fracture strength in which the occurrence of slippage, cracking, and the like is suppressed due to the positional relationship of the cleavage planes of the first and second single crystal silicon substrates to be bonded together.

[0014] In this case, the first silicon single crystal substrate and the second silicon single crystal substrate to be prepared may have a diameter of 300 mm or more.

[0015] Substrates with high breaking strength such as electronic device substrates manufactured by the manufacturing method of the present invention are particularly effective for manufacturing large-diameter electronic device substrates, such as those having a diameter of 300 mm or more. Effect of the Invention

[0016] With the electronic device substrate and the manufacturing method thereof of the present invention, it is possible to provide an electronic device substrate having high fracture strength in which the occurrence of cracks and the like is suppressed due to the positional relationship of the cleavage planes of the first silicon single crystal substrate and the second silicon single crystal substrate. [Brief description of the drawings]

[0017] [Figure 1] 1 is a schematic diagram showing an example of a cleavage plane of a first silicon single crystal substrate and a second silicon single crystal substrate in a substrate for an electronic device of the present invention. FIG. [Diagram 2] 4 is a schematic diagram showing an example of cleavage planes of a first silicon single crystal substrate and a second silicon single crystal substrate in a comparative example. FIG. [Diagram 3] 1 is a schematic cross-sectional view showing an example of a substrate for an electronic device of the present invention. [Figure 4] FIG. 1 is a flow chart showing an outline of an example of a method for producing a substrate for an electronic device according to the present invention. [Diagram 5] 1 is a photograph showing a state in which two silicon single crystal substrates are superimposed and heat-treated in an example and a comparative example. [Figure 6] FIG. 2 is a schematic diagram showing a breaking load and bending strength test. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The present invention will be described in detail below, but the present invention is not limited thereto.

[0019] As described above, in order to increase the withstand voltage of epitaxial substrates for power devices, it is necessary to fabricate substrates for electronic devices in which a nitride semiconductor film is formed thick on a silicon single crystal substrate (for example, GaN on Si in which the thickness of the GaN epitaxial layer is increased). To increase the thickness of the epitaxial layer, the silicon single crystal substrate can be made thicker and epitaxially grown. As a method for thickening the silicon substrate, two silicon single crystal substrates are bonded together, but even when bonded substrates are used, it has not been possible to completely prevent the occurrence of slippage, cracking, and the like.

[0020] The present inventors have conducted extensive research into substrates for electronic devices having high fracture strength and suppressed occurrence of slips, cracks, and the like, and have found that in a substrate for electronic devices having a nitride semiconductor film formed on a bonded substrate of silicon single crystals, by using two bonded silicon single crystal substrates as a base substrate (seed crystal) and further misaligning not only the crystal plane orientations of the main surfaces of the two silicon single crystal substrates but also the cleavage planes of each substrate, it is possible to obtain a substrate for electronic devices having high fracture strength and suppressed occurrence of slips, cracks, and the like, and have completed the present invention.

[0021] [Substrates for electronic devices] The present invention provides a substrate for an electronic device in which a nitride semiconductor film is formed on a bonded substrate of silicon single crystal, the bonded substrate being a substrate in which a first silicon single crystal substrate having a crystal plane orientation of {111} and a second silicon single crystal substrate having a crystal plane orientation of {100} are bonded together via an oxide film, the first silicon single crystal substrate being: <110> The second silicon single crystal substrate has a notch formed in the direction of the <011> Direction or <001> A notch is formed in the first silicon single crystal substrate in the direction <110> and the second silicon single crystal substrate. <011> The substrate for electronic devices is characterized in that the nitride semiconductor film is formed on a surface of the first silicon single crystal substrate of the bonded substrate, the first silicon single crystal substrate being bonded at an angle ranging from -15° to 15°.

[0022] The present invention will now be described in further detail with reference to the accompanying drawings.

[0023] As shown in FIG. 3, an electronic device substrate 20 of the present invention has a nitride semiconductor film 21 formed on a bonded substrate 10 of silicon single crystals. In the explanation of the present invention, the bonded substrate 10 of silicon single crystals is also simply referred to as a "bonded substrate." In this case, the bonded substrate 10 is a substrate in which a first silicon single crystal substrate 11 having a crystal plane orientation of {111} and a second silicon single crystal substrate 12 having a crystal plane orientation of {100} are bonded via an oxide film 13. Furthermore, the first silicon single crystal substrate 11 is <110> The second silicon single crystal substrate 12 has a notch formed in the direction. <011> Direction or <001> The bonded substrate 10 has a notch formed in the direction of the first silicon single crystal substrate 11. <110> direction and the second silicon single crystal substrate 12 <011> The directions are bounded by an angle range of -15° to 15°.

[0024] In this specification, the line above the number in the usual Miller index notation is replaced with a "-" before the number. For example, the notation [1-10] is

number

[0025] The notation of Miller indices is as usual. That is, {} is the general term for equivalent crystal plane orientations, () means each crystal plane orientation, <> is the general term for equivalent crystal axis directions, and [] means each crystal axis direction.

[0026] The bonding state of the first silicon single crystal substrate 11 and the second silicon single crystal substrate 12 will be described with reference to Fig. 1 as a view from the main surface side of each substrate. Here, the first silicon single crystal substrate 11 will be described as having a crystal plane orientation of {111} and a notch at the position of [1-10], and the second silicon single crystal substrate 12 will be described as having a crystal plane orientation of {100} and a notch at the position of [0-11].

[0027] In FIG. 1, the cleavage plane of the first silicon single crystal substrate 11 is shown by a dotted line, and the cleavage plane of the second silicon single crystal substrate 12 is shown by a dashed line. As shown in FIG. 1, when the first silicon single crystal substrate 11 and the second silicon single crystal substrate 12 are superimposed, it can be seen that the cleavage planes in the vertical direction in the figure are shifted. Although the cleavage planes in the horizontal direction in the figure are superimposed, the substrate strength of the bonded substrate 10 as a whole is improved due to the effect of the cleavage planes in the vertical direction in the figure being shifted. As a result, even if the nitride semiconductor film 21 formed on the surface of the first silicon single crystal substrate 11 of the bonded substrate 10 exists, it is possible to provide a substrate 20 for electronic devices having high fracture strength in which the occurrence of slips, cracks, etc. is suppressed.

[0028] In the electronic device substrate 20 of the present invention, the surface of the first silicon single crystal substrate 11 has a crystal plane orientation of {111}. above Since the nitride semiconductor film 21 is formed on the nitride semiconductor film 21, a good nitride semiconductor film 21 is formed.

[0029] FIG. 2 shows an example of a bonded substrate that is not the present invention. In FIG. 2, the first silicon single crystal substrate has a crystal plane orientation of {111} and a notch at the position of [1-10], and the second silicon single crystal substrate has a crystal plane orientation of {100} and a notch at the position of

[0001] . In this case, the crystal axis direction in which the notch of the second silicon single crystal substrate is formed is different from that in FIG. 1, but the other aspects are the same as in FIG. 1. As can be seen from FIG. 2, when the first silicon single crystal substrate 11 and the second silicon single crystal substrate 12 are superimposed, all of the cleavage planes are in a positional relationship close to each other. Even in the case of FIG. 2, two silicon single crystal substrates with crystal plane orientations of {111} and {100} are bonded together, so that the strength of the bonded substrate and the substrate for electronic devices is high, but the strength is inferior to that of the case of FIG. 1 showing the present invention.

[0030] The present inventors further carried out the following experiment to examine the breaking load and bending strength in the angle range between FIG. 1 and FIG.

[0031] <110> a silicon single crystal substrate having a crystal plane orientation of {111} and a notch formed in the {111} direction; <011> The state where the notch of the silicon single crystal substrate with the crystal plane orientation of {100} is aligned with the notch of the silicon single crystal substrate with the crystal plane orientation of {111} <110> orientation and {100} of silicon single crystal substrate <011> The breaking load was investigated by shifting the direction angle from 0° to 5°, 10°, 15°, 20°, 30°, 40°, and 45°.

[0032] In measuring the strength of this bonded substrate, the breaking load and bending strength were examined using an Instron precision universal testing machine, as shown in Figure 6. Figure 6(b) is a side view of Figure 6(a) as seen from above in the vertical direction.

[0033] As shown in Figures 6(a) and (b), three fulcrum jigs J (the radius of curvature R of the bonding point is 15 mm) were placed above and below the bonded substrate. In the bonded substrate, the notch position of the {111} silicon single crystal substrate is weak in strength, so the notch position N of the {111} silicon single crystal substrate was set directly below the central fulcrum jig J (see Figures 6(a) and (b)). The bending strength was calculated as follows:

[0034] Bending strength = 3PL / 2WT 2 (calculation formula) P: breaking load, L=distance between fulcrums (150mm) W: Width 300mm T: Thickness 1.55mm

[0035] The investigation yielded the results shown in Table 1. [Table 1]

[0036] In this way, the {111} silicon single crystal substrate <110> orientation and {100} of silicon single crystal substrate <011> It is clear that substrates bonded in an angle range of -15° to 15° (0° to 15° and 15° to 0° are equivalent due to crystal symmetry) have large breaking loads and bending strengths, indicating that the substrate strength is high.

[0037] In the electronic device substrate 20 of the present invention, since the substrate strength is high as described above, the diameter of the combined substrate 10 (and the electronic device substrate 20) can be as large as 300 mm or more. Conventionally, substrates with such a large diameter have sometimes not had sufficient substrate strength, resulting in the occurrence of slips, cracks, etc., but the present invention can provide an electronic device substrate with high fracture strength in which these problems are suppressed. There is no particular upper limit on the diameter of the combined substrate 10 (and the electronic device substrate 20), but it can be, for example, 450 mm or less.

[0038] When the diameter of the bonded substrate 10 (and the electronic device substrate 20) is 300 mm or more, the diameters of the first silicon single crystal substrate 11 and the second silicon single crystal substrate 12 are also 300 mm or more. The thicknesses of the first silicon single crystal substrate 11 and the second silicon single crystal substrate 12 are not particularly limited, but substrates conforming to the standards can be suitably used. In particular, when the diameter is 300 mm, the thickness can be 775 μm. Such silicon single crystal substrates are used as ordinary device substrates, are inexpensive, and can be used without any particular problems. The thicknesses of the first silicon single crystal substrate 11 and the second silicon single crystal substrate 12 can be, for example, 500 μm to 1500 μm.

[0039] [Method of manufacturing substrates for electronic devices] A method for producing the above-described electronic device substrate 20 of the present invention will now be described with reference to FIG.

[0040] First, as shown in S11 of FIG. 4, a first silicon single crystal substrate 11 and a second silicon single crystal substrate 12 are prepared (step S11). At this time, the first silicon single crystal substrate 11 has a crystal plane orientation of {111}, <110> A silicon single crystal substrate having a notch formed in the direction is prepared. A second silicon single crystal substrate 12 having a crystal plane orientation of {100} and <011> Direction or <001> In the present invention, a silicon single crystal substrate having a notch formed in the first direction is prepared. At this time, the diameter of the first silicon single crystal substrate and the second silicon single crystal substrate to be prepared may be 300 mm or more.

[0041] In addition, since the first silicon single crystal substrate 11 and the second silicon single crystal substrate 12 are bonded together to form a bonded substrate 20 of one silicon single crystal substrate, the first silicon single crystal substrate 11 can also be called a bond wafer, and the second silicon single crystal substrate 12 can also be called a base wafer.

[0042] The thickness of each of the first silicon single crystal substrate 11 and the second silicon single crystal substrate 12 is not particularly limited, but a substrate having a thickness according to a standard can be suitably used. The resistivity and impurity concentration of each of the first silicon single crystal substrate 11 and the second silicon single crystal substrate 12 can be set appropriately.

[0043] Next, as shown in S12 of FIG. 4, at least one of the first silicon single crystal substrate 11 and the second silicon single crystal substrate 12 is thermally oxidized to form an oxide film on the surface (step S12). The oxide film formed here will become the oxide film 13 shown in FIG. 3 after the two silicon single crystal substrates are bonded. The method of forming this oxide film is not particularly limited, but for example, an oxide film with a thickness of about 100 nm can be formed on the surface by performing an oxidation heat treatment. The thickness of the oxide film is not particularly limited, but can be, for example, 10 nm or more and 1000 nm or less. An oxide film may be formed on each of the two silicon single crystal substrates, or an oxide film may be formed on one of the silicon single crystal substrates.

[0044] Next, as shown in S13 of FIG. 4, the first silicon single crystal substrate 11 and the second silicon single crystal substrate 12 are bonded together (step S13). <110> direction and the second silicon single crystal substrate 12 <011> The first silicon single crystal substrate 11 and the second silicon single crystal substrate 12 are overlapped with each other so that the direction is in the angle range of -15° to 15°. At this time, the two silicon single crystal substrates are overlapped via the oxide film formed in step S12. By performing a heat treatment in this state, the first silicon single crystal substrate 11 and the second silicon single crystal substrate 12 are bonded to each other, and a bonded substrate 10 (see FIG. 3) is produced.

[0045] The conditions (atmosphere, temperature, time, etc.) of the heat treatment (bonding heat treatment) are not particularly limited as long as they are sufficient to bond the first silicon single crystal substrate 11 and the second silicon single crystal substrate 12. The temperature of this bonding heat treatment can be, for example, 400° C. or higher and 1200° C. or lower in a nitrogen atmosphere for 1 to 12 hours.

[0046] After this bonding heat treatment, it is preferable to clean the surface of the bonded substrate 10 before epitaxial growth of the nitride semiconductor film described below. In particular, it is preferable to remove an oxide film formed on the surface of the bonded substrate 10 (particularly the surface of the first silicon single crystal substrate 11) by hydrofluoric acid spin cleaning or the like.

[0047] In this way, the first silicon single crystal substrate 11 and the second silicon single crystal substrate 12 are bonded to produce the bonded substrate 10, and then, as shown in S14 of FIG. 4, a nitride semiconductor film 21 (see FIG. 3) is epitaxially grown on the surface of the first silicon single crystal substrate 11 of the bonded substrate 10 (step S14). The nitride semiconductor film 21 may be an AlN layer, a GaN layer, an AlGaN layer, or the like. This nitride semiconductor film 21 may be formed by a normal method. In addition, an intermediate layer (buffer layer) may be formed as appropriate. In this way, the electronic device substrate 20 shown in FIG. 3 may be manufactured. EXAMPLES

[0048] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0049] (Example) According to the method for producing a substrate for an electronic device of the present invention shown in FIG. 4, the substrate for an electronic device 20 shown in FIG. 3 was produced.

[0050] First, a double-sided polished silicon single crystal substrate 11 having a diameter of 300 mm, a thickness of 775 μm, a crystal plane orientation of {111}, a resistivity of 5500 Ωcm, and a notch formed in the [1-10] direction was prepared as the first silicon single crystal substrate 11, and a double-sided polished silicon single crystal substrate 12 having a diameter of 300 mm, a thickness of 775 μm, a crystal plane orientation of {100}, a resistivity of 10 Ωcm, and a notch formed in the [0-11] direction was prepared (step S11). Such a second silicon single crystal substrate 12 is sometimes referred to as a "0° notch substrate". Each of these first silicon single crystal substrate 11 and second silicon single crystal substrate 12 has a cleavage plane as shown in the conceptual diagram of FIG. 1.

[0051] The two prepared silicon single crystal substrates were subjected to an oxidation heat treatment to form an oxide film having a thickness of 100 nm on each substrate (step S12).

[0052] Next, the two silicon single crystal substrates were bonded together with their notches aligned, and a bonding heat treatment was performed at 500° C. in a nitrogen atmosphere (see FIG. 5) to produce a bonded substrate 10 (step S13). After that, the bonded substrate 10 was spin-cleaned with hydrofluoric acid to remove the oxide film on the surface.

[0053] Next, on the surface of the first silicon single crystal substrate 11 of the bonded substrate 10, a nitride semiconductor film 21 was epitaxially grown to a total thickness of 1.8 μm, comprising a 150 nm AlN layer, a 160 nm AlGaN layer, a superlattice structure in which 50 pairs of GaN layers and AlN layers were alternately stacked, a 1000 nm GaN layer, a 20 nm AlGaN layer, and a 3 nm GaN layer (step S14).

[0054] As a result, GaN could be formed without the occurrence of cracks or slippage. In this manner, the electronic device substrate 20 was manufactured.

[0055] (Comparative Example) As described below, a substrate for an electronic device was manufactured in the same manner as in the example, except that a second silicon single crystal substrate in which a notch was formed had a crystal axis direction different from that of the example.

[0056] First, a double-sided polished silicon single crystal substrate with a diameter of 300 mm, a thickness of 775 μm, a crystal plane orientation of {111}, a resistivity of 5500 Ωcm, and a notch formed in the [1-10] direction was prepared as the first silicon single crystal substrate, and a double-sided polished silicon single crystal substrate with a diameter of 300 mm, a thickness of 775 μm, a crystal plane orientation of {100}, a resistivity of 21 Ωcm, and a notch formed in the

[0001] direction was prepared as the second silicon single crystal substrate 12. Such a second silicon single crystal substrate is sometimes called a "45° notch substrate." Each of these first silicon single crystal substrate and second silicon single crystal substrate has a cleavage plane as shown in the conceptual diagram of FIG. 2.

[0057] The two silicon single crystal substrates thus prepared were subjected to an oxidation heat treatment to form an oxide film of 100 nm in thickness on each of them.

[0058] Next, the two silicon single crystal substrates were bonded together with their notches aligned, and a bonding heat treatment was performed at 500°C in a nitrogen atmosphere (see Fig. 5) to produce a bonded substrate. This heat treatment process was performed simultaneously with the bonding heat treatment process in the embodiment, as shown in Fig. 5. Thereafter, the bonded substrate 10 was spin-cleaned with hydrofluoric acid to remove the oxide film on the surface.

[0059] Next, a GaN film was epitaxially grown as a nitride semiconductor film on the surface of the first silicon single crystal substrate of the bonded substrate under the same conditions as in the example.

[0060] As a result, GaN was successfully formed, but slippage occurred at the notch.

[0061] The present invention is not limited to the above-described embodiment. The above-described embodiment is merely an example, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and exhibits similar effects is included in the technical scope of the present invention. [Explanation of symbols]

[0062] 10...Silicon single crystal bonded substrate, 11...first silicon single crystal substrate, 12...second silicon single crystal substrate, 13...Oxide film, 20...Substrates for electronic devices, 21...Nitride semiconductor film.

Claims

1. A substrate for an electronic device in which a nitride semiconductor film is formed on a silicon single crystal bonded substrate, The bonded substrate is a substrate in which a first silicon single crystal substrate having a crystal plane orientation of {111} and a second silicon single crystal substrate having a crystal plane orientation of {100} are bonded together via an oxide film; the first silicon single crystal substrate has a notch formed in a <110> direction; the second silicon single crystal substrate has a notch formed in a <011> direction or a <001> direction; the <110> direction of the first silicon single crystal substrate and the <011> direction of the second silicon single crystal substrate are bonded at an angle in the range of −15° to 15°; A substrate for electronic devices, characterized in that the nitride semiconductor film is formed on a surface of the first silicon single crystal substrate of the bonded substrate.

2. 2. The substrate for electronic devices according to claim 1, wherein the diameter of the bonded substrate is 300 mm or more.

3. A method for manufacturing a substrate for an electronic device, comprising forming a nitride semiconductor film on a bonded substrate of silicon single crystal, preparing a first silicon single crystal substrate having a notch formed in a <110> direction and a crystal plane orientation of {111}, and a second silicon single crystal substrate having a notch formed in a <011> direction or a <001> direction and a crystal plane orientation of {100}; a step of thermally oxidizing at least one of the first silicon single crystal substrate and the second silicon single crystal substrate to form an oxide film on a surface thereof; a step of bonding the first silicon single crystal substrate and the second silicon single crystal substrate together via the oxide film so that the angle between the <110> direction of the first silicon single crystal substrate and the <011> direction of the second silicon single crystal substrate is within the range of −15° to 15°, and performing a heat treatment to bond the first silicon single crystal substrate and the second silicon single crystal substrate to produce the bonded substrate; epitaxially growing the nitride semiconductor film on a surface of the first silicon single crystal substrate of the bonded substrate; 2. A method for producing a substrate for an electronic device, comprising:

4. 4. The method for manufacturing a substrate for an electronic device according to claim 3, wherein the first silicon single crystal substrate and the second silicon single crystal substrate each have a diameter of 300 mm or more.

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