Semiconductor substrate manufacturing method and semiconductor substrate manufacturing apparatus

Abstract

The present invention attempts to solve the problem of providing novel technology that makes it possible to grow high-quality semiconductor substrates.　In order to solve the abovementioned problem, the present invention provides: a method for producing semiconductor substrates that includes an installation step in which starting substrates and starting materials are installed in an alternating manner and a heating step in which the starting substrates and the starting materials are heated and a growth layer is formed on the starting substrates; and a device for producing the semiconductor substrates. Owing to this configuration, the present invention makes it possible to simultaneously achieve desired growth conditions in each of a plurality of starting substrates and thereby provide novel technology that makes it possible to grow high-quality semiconductor substrates.

Description

[Technical field]

[0001] The present invention relates to a method and an apparatus for manufacturing a semiconductor substrate. [Background technology]

[0002] Materials such as SiC (silicon carbide), GaN (gallium nitride), and Ga2O3 (gallium oxide) are attracting attention as next-generation semiconductor materials to replace Si (silicon) and GaAs (gallium arsenide).

[0003] For example, SiC has an electric breakdown field one order of magnitude larger than that of Si, a band gap three times larger, and a thermal conductivity three times higher than that of Si. Therefore, SiC is expected to be used in power devices, high-frequency devices, high-temperature operating devices, etc.

[0004] Typically, SiC substrates used in the fabrication of SiC semiconductor devices are manufactured by slicing a single crystal SiC ingot. The main method for growing this ingot is the sublimation recrystallization method (modified Lely process) (see Patent Document 1, etc.). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 3-295898 Summary of the Invention [Problem to be solved by the invention]

[0006] In the modified Lely process, the sublimation gas of the SiC raw material is recrystallized on the surface of a single crystal substrate (seed crystal), and the ingot grows. Therefore, the surface after recrystallization (growth) becomes the new growth surface, and this process is repeated to realize the long ingot.

[0007] However, this sublimation recrystallization method had the problem that the quality of the single crystal SiC varied depending on the part of the ingot because the growth conditions changed from moment to moment as the growth surface moved, making it difficult to grow high-quality single crystal SiC over the entire ingot.

[0008] Specifically, the growth surface of the ingot moves as the ingot grows, which changes the distance between the growth surface and the SiC raw material and the relative position between the growth surface and the heater, resulting in different growth conditions near the growth surface between the early and later stages of the ingot growth.

[0009] As a result, while high-quality single crystal SiC can be obtained in one part of the ingot under the desired growth conditions, in another part of the ingot, the preferred growth conditions deviate, resulting in the occurrence of dislocations, the inclusion of other polymorphs, the occurrence of subgrain boundaries, etc., and the failure to obtain high-quality single crystal SiC.

[0010] In view of the above problems, an object of the present invention is to provide a new technique capable of growing a high-quality semiconductor substrate. [Means for solving the problem]

[0011] In order to solve the above problems, the present invention provides a method for manufacturing a semiconductor substrate, including a step of alternately placing original substrates and source materials, and a step of heating the original substrates and source materials to form a growth layer on the original substrates. With this configuration, the present invention can simultaneously achieve desired growth conditions for each of a plurality of original substrates, thereby providing a new technology capable of growing high-quality semiconductor substrates.

[0012] In a preferred embodiment of the present invention, the placing step places the original substrate and the source body in a quasi-closed space. With this configuration, the present invention can realize the transport of the source material between the original substrate and the source body under a desired vapor pressure environment.

[0013] In a preferred embodiment of the present invention, the heating step heats the original substrate and the source body so as to generate a temperature difference between the original substrate and the source body. With this configuration, the present invention can realize source transport between the original substrate and the source body using the temperature gradient between the original substrate and the source body as a driving force.

[0014] In a preferred embodiment of the present invention, the method further comprises a step of separating a part of the original substrate having the growth layer. With this configuration, the present invention can separate a high-quality semiconductor substrate from a substrate including the growth layer.

[0015] In a preferred embodiment of the present invention, the separation step includes an introduction step of introducing a damage layer into the original substrate having the growth layer, and a peeling step of peeling off a part of the original substrate having the growth layer. With this configuration, the present invention can introduce a damage layer to a desired depth from the surface of the original substrate, and separate a high-quality semiconductor substrate from the original substrate having the growth layer.

[0016] In a preferred embodiment of the present invention, the source substrate and the source body are placed in close contact with each other in the placing step. The present invention can provide a novel, economical technology that can increase the number of source substrates on which a growth layer is formed and can grow a high-quality semiconductor substrate.

[0017] In a preferred embodiment of the present invention, the setting step includes setting a source material transport prevention body between unit processing bodies including the source substrate and the source material body, the source material transport prevention body preventing source material transport between the source substrate and the source material body. With this configuration, the present invention can realize crystal growth that forms a growth layer on the main surface or the back surface of the source substrate.

[0018] In a preferred embodiment of the present invention, the raw substrate and the source body contain a SiC material. With this configuration, the present invention can provide a novel technique for growing a high-quality SiC semiconductor substrate.

[0019] In order to solve the above problems, the present invention provides a substrate manufacturing apparatus having a main container in which original substrates and source materials can be alternately placed, and a heating furnace capable of heating the original substrates and source materials and forming a growth layer on the original substrates. With this configuration, the present invention can simultaneously achieve desired growth conditions for each of a plurality of original substrates, thereby providing a new technology capable of growing high-quality semiconductor substrates.

[0020] In a preferred embodiment of the present invention, the main container has a semi-closed space therein. With this configuration, the present invention can realize the transport of the raw material between the source substrate and the raw material body under a desired vapor pressure environment.

[0021] In a preferred embodiment of the present invention, the main container can be configured to stack the original substrate, the source body, the source transport prevention body, the original substrate, and the source body in this order, and to accommodate the original substrate, the source body, the source transport prevention body, the original substrate, and the source body. With this configuration, the present invention can realize crystal growth in which a growth layer is formed only on the main surface or the back surface of the original substrate.

[0022] In a preferred embodiment of the present invention, the heating furnace is capable of forming a temperature gradient between the original substrate and the source body. With such a configuration, the present invention can realize source transport between the original substrate and the source body using the temperature gradient between the original substrate and the source body as a driving force.

[0023] In a preferred embodiment of the present invention, the semiconductor device further comprises a separating means capable of separating a part of the original substrate having the growth layer. With such a configuration, the present invention can separate a high-quality semiconductor substrate from a substrate including the growth layer.

[0024] In a preferred embodiment of the present invention, the separation means includes an introduction means capable of irradiating the original substrate having the growth layer with a laser beam to introduce a damage layer into the original substrate having the growth layer, and a peeling means capable of peeling off a part of the original substrate having the growth layer. With this configuration, the present invention can introduce a damage layer to a desired depth from the surface of the original substrate, thereby manufacturing a high-quality semiconductor substrate.

[0025] In a preferred embodiment of the present invention, the raw substrate and the source body contain a SiC material. With this configuration, the present invention can provide a novel technique for growing a high-quality SiC semiconductor substrate. Effect of the Invention

[0026] The disclosed technology provides a novel technology that allows for the growth of high quality semiconductor substrates.

[0027] Other objects, features and advantages will become apparent from a reading of the following detailed description when taken in conjunction with the drawings and the claims. [Brief description of the drawings]

[0028] [Figure 1] 1A to 1C are explanatory diagrams of a method for manufacturing a semiconductor substrate according to an embodiment of the present invention. [Diagram 2] 1A to 1C are explanatory diagrams of a method for manufacturing a semiconductor substrate according to an embodiment of the present invention. [Diagram 3] 1A to 1C are explanatory diagrams of a method for manufacturing a semiconductor substrate according to an embodiment of the present invention. [Figure 4] 1 is an explanatory diagram of a semiconductor substrate manufacturing apparatus according to an embodiment of the present invention; [Diagram 5] 1 is an explanatory diagram of a semiconductor substrate manufacturing apparatus according to an embodiment of the present invention; [Figure 6] 1 is an explanatory diagram of a semiconductor substrate manufacturing apparatus according to an embodiment of the present invention; [Figure 7] 1 is an explanatory diagram of a semiconductor substrate manufacturing apparatus according to an embodiment of the present invention; [Figure 8]1 is an explanatory diagram of a semiconductor substrate manufacturing apparatus according to an embodiment of the present invention; [Figure 9] FIG. 1 is an explanatory diagram regarding the evaluation of BPD number in Reference Example 1. [Figure 10] 1 is an SEM image of a substrate surface in Reference Example 2. [Figure 11] 1 is an SEM image of a substrate surface in Reference Example 2. [Figure 12] 11 is a correlation diagram between the growth rate and the heating temperature of the semiconductor substrate in Reference Example 3. FIG.

[0029] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. The technical scope of the present invention is not limited to the embodiment shown in the attached drawings, and can be appropriately modified within the scope of the claims.

[0030] <<Method for manufacturing semiconductor substrate>> A method for manufacturing a substrate according to one embodiment of the present invention (hereinafter simply referred to as the manufacturing method) will be described in detail below. Although this specification illustrates an example in which SiC crystal growth is performed using a SiC material, the same effects can be obtained with semiconductor materials such as GaN (gallium nitride) and Ga2O3 (gallium oxide). Therefore, the original substrate 11 and the source body 12 are semiconductor materials such as SiC, GaN, and Ga2O3.

[0031] The present invention can be understood as a manufacturing method including an arrangement step S1 in which original substrates 11 and raw material bodies 12 are arranged alternately, a heating step S2 in which the original substrates 11 and raw material bodies 12 are heated to form a growth layer 111 on the original substrate 11, and a separation step S3 in which a portion of the original substrate 11 heated in the heating step S2 is separated.

[0032] <Installation process S1> In the setting step S1 according to one embodiment of the present invention, the original substrates 11 and the raw material bodies 12 are alternately set. At this time, the original substrates 11 and the raw material bodies 12 are set so as to be substantially parallel to each other. At this time, there is no limit to the respective numbers of the original substrates 11 and the raw material bodies 12 set in the setting step S1.

[0033] In the placement step S1, the original substrate 11 and the raw material body 12 are placed in a semi-closed space. In the description of this specification, the term "semi-closed space" refers to a space in which it is possible to evacuate the inside of the space, but which is capable of containing at least a portion of the steam generated inside the space.

[0034] In the placement step S1, the original substrate 11 and the raw material body 12 are placed so as to be in close contact with each other. In the description of this specification, the term "close contact" refers to different members being close to each other while maintaining a predetermined distance therebetween.

[0035] In the setting step S1, a raw material transport prevention body 28 for preventing raw material transport between the raw material substrate 11 and the raw material body 12, which will be described later, is set between the unit processing bodies 1X including the raw material substrate 11 and the raw material body 12. The "unit processing body 1X" in the description in this specification can be understood as consisting of one raw substrate 11 and one raw material body 12, for example, or as consisting of a plurality of raw substrates 11 and a plurality of raw material bodies 12, for example. The setting step S1 according to one embodiment of the present invention can be understood as setting one or more unit processing bodies 1X.

[0036] <Original substrate 11 and raw material body 12> Examples of the original substrate 11 include a SiC wafer sliced ​​into a disk shape from an ingot produced by a sublimation method or the like, and a SiC substrate processed into a thin plate shape from a SiC single crystal. Any polytype can be used as the crystal polymorph of the SiC single crystal.

[0037] The source material 12 preferably has the same material as the original substrate 11 and contains at least the atomic species constituting the original substrate 11. As with the original substrate 11, the source material 12 may be a SiC wafer sliced ​​into a disk shape from an ingot produced by a sublimation method or the like, and may be a single crystal substrate or a polycrystalline substrate. The source material 12 may also be a processed product such as a sintered body containing polycrystalline SiC.

[0038] An example of the surface of a SiC single crystal substrate according to one embodiment of the present invention is a surface having an off angle of several degrees (for example, 0.4 to 8.0°) from the (0001) or (000-1) plane (note that in this specification, in the notation of Miller indices, "-" refers to a bar attached to the index immediately following it).

[0039] A step-terrace structure can be observed on the planarized SiC single crystal substrate surface. This step-terrace structure is a staircase structure in which steps, which are step portions of one molecular layer or more, and terraces, which are flat portions where the {0001} plane is exposed, are arranged alternately. The steps on the planarized SiC single crystal substrate surface have a minimum height (minimum unit) of one molecular layer (0.25 nm), and various step heights are formed by overlapping multiple one molecular layers.

[0040] In the description of this specification, the step bunching, which is so large that it has a height exceeding one unit cell of each polytype, is called macro step bunching (MSB). That is, an MSB is a bunching step exceeding four molecular layers (five molecular layers or more) in the case of 4H-SiC, and a bunching step exceeding six molecular layers (seven molecular layers or more) in the case of 6H-SiC. It is desirable that MSBs are not formed on the substrate surface, since they are one of the factors that can cause defects on the surface during growth layer formation and can impair the reliability of oxide films in SiC semiconductor devices.

[0041] The original substrate 11 and the raw material body 12 may have a chip size of a few centimeters square to a wafer size of 6 inches or more, for example, and there is no limit to the size.

[0042] The original substrate 11 has a main surface 113 (not shown) and a back surface 114. The source body 12 has a main surface 123 and a back surface 124 (not shown).

[0043] In the description of this specification, the term "front surface" refers to both the main surface and the back surface. In addition, in the description of this specification, the term "one side" refers to either the main surface or the back surface, and the other side refers to the surface of the same substrate opposite to the one side. In the description of this specification, the growth layer 111 refers to a growth layer formed on the original substrate 11 by transporting raw materials. In the description of this specification, the growth layer 121 refers to a growth layer formed on the source body 12 by source transport.

[0044] The surface of the growth layer formed on the original substrate 11 preferably has a basal plane dislocation (BPD) density reduced as much as possible. In addition, in the formation of the growth layer 111, etc., the BPDs are preferably converted into other defects / dislocations including threading edge dislocations (TEDs).

[0045] <Heating process S2> In the heating step S2, the original substrate 11 and the source material 12 are heated so that a temperature difference is generated between the original substrate 11 and the source material 12, so that the original substrate 11 undergoes crystal growth and a growth layer 111 is formed on the surface of the original substrate 11.

[0046] As shown in FIG. 1, in the heating step S2, the original substrate 11 is placed on the low temperature side, so that the growth layer 111 is formed on the original substrate 11 (rear surface 114) and the source body 12 (main surface 123) is etched simultaneously.

[0047] In the heating step S2, the raw substrate 11 and the raw material body 12 are heated in a semi-closed space.

[0048] 2, in the original substrate 11 and the source material body 12, the transport of source material based on the following reactions 1) to 5) is continuously performed, and it can be understood that, for example, a growth layer 121 is formed on the source material body 12. This is also true in the case of forming a growth layer 111 on the original substrate 11. Incidentally, although the original substrate 11 and the source material body 12 according to one embodiment of the present invention are in close contact with each other, even in this case, it can be understood that the minute gap between the original substrate 11 and the source material body 12 serves as the source material transport space.

[0049] 1) SiC(s) → Si(v) + C(s) 2) 2C(s)+Si(v)→SiC2(v) 3) C(s)+2Si(v) → Si2C(v) 4) Si(v) + SiC2(v) → 2SiC(s) 5) Si2C(v) → Si(v) + SiC(s)

[0050] Explanation of 1): When the rear surface 114 of the original substrate 11 is thermally decomposed, Si atoms (Si(v)) are released from the rear surface 114 . Explanation of 2) and 3): When Si atoms (Si(v)) are released, the C atoms (C(s)) remaining on the back surface 114 react with the Si vapor (Si(v)) in the raw material transport space to become Si2C or SiC2, etc., and sublime into the raw material transport space. Explanation of 4) and 5): The sublimated Si2C or SiC2, etc., reaches and diffuses onto the terraces of the main surface 123 of the source material 12 due to the temperature gradient, and when it reaches the steps, the growth layer 121 grows and is formed while inheriting the polytype of the main surface 123 (step-flow growth).

[0051] The heating step S2 includes a Si atom sublimation step S21 in which Si atoms are thermally sublimated from the surface of the original substrate 11 or the raw material body 12, and a C atom sublimation step S22 in which C atoms remaining on the surface of the original substrate 11 or the raw material body 12 are sublimated by bonding with Si atoms in the raw material transport space. The heating step S2 also includes an etching step S23 in which the surface of the original substrate 11 or the source body 12 is etched based on a Si atom sublimation step S21 and a C atom sublimation step S22. The heating step S2 includes, for example, a growing step S24 in which the surface of the source body 12 is etched while a growth layer 111 is formed on the surface of the original substrate 11 based on the above-mentioned step flow growth. Each step included in the heating step S2 is performed sequentially. The growth step S24 can be understood as a step based on PVT (physical vapor transport) since the transported Si2C or SiC2, etc. become supersaturated and condense to form the growth layer 111. Moreover, the heating step S2 can be understood to include a bunching decomposition step of decomposing the MSBs on the surface of the SiC single crystal substrate.

[0052] It can be understood that the driving force for the transport of the raw material in the heating step S2 is the vapor pressure difference caused by the formed temperature gradient between the raw substrate 11 and the raw material body 12. Therefore, it can be understood that not only the temperature difference on the respective surfaces of the raw substrate 11 and the raw material body 12, but also the vapor pressure difference and chemical potential difference caused by the crystal structure between the raw substrate 11 and the raw material body 12 can be the driving force for the transport of the raw material.

[0053] In addition, the heating process S2 can be understood to form a growth layer 111 only on the main surface or back surface of the original substrate 11 when the original substrate 11, raw material body 12, raw material transport prevention body 28, original substrate 11 and raw material body 12 are stacked in this order.

[0054] The SiC material as part of the device that forms the quasi-closed space in the heating step S2 can be the source body 12 as appropriate.

[0055] In the heating step S2, the raw material is transported by supplying a dopant gas into the semi-closed space by a dopant gas supplying means, thereby adjusting the doping concentration of the growth layer 111. When the dopant gas is not supplied into the semi-closed space by the dopant gas supplying means, it can be understood that the growth layer 111 inherits the doping concentration in the semi-closed space.

[0056] The raw material transport in the heating step S2 is preferably performed in an environment having a gas phase species containing Si element and a gas phase species containing C element, more preferably in a SiC-Si equilibrium vapor pressure environment, and more preferably in a SiC-C equilibrium vapor pressure environment.

[0057] In the description of this specification, the term "SiC-Si vapor pressure environment" refers to a vapor pressure environment in which SiC (solid) and Si (liquid phase) are in phase equilibrium via the gas phase. In addition, in the description of this specification, the "SiC-C equilibrium vapor pressure environment" refers to a vapor pressure environment when SiC (solid phase) and C (solid phase) are in phase equilibrium via the gas phase.

[0058] The SiC-Si equilibrium vapor pressure environment is formed by heating a semi-closed space with an atomic ratio of Si / C exceeding 1. The SiC-C equilibrium vapor pressure environment is formed by heating a semi-closed space with an atomic ratio of Si / C of 1 or less.

[0059] The heating temperature in the heating step S2 is preferably set in the range of 1400 to 2300°C, and more preferably in the range of 1600 to 2000°C.

[0060] The heating time in the heating step S2 can be set to any time so as to obtain a desired etching amount. For example, when the etching rate is 1.0 μm / min, in order to set the etching amount to 1.0 μm, the heating time is 1 min (1 minute).

[0061] The temperature gradient in the heating step S2 is set, for example, in the range of 0.1 to 5.0° C. / mm, and is desirably uniform in the raw material transport space.

[0062] The etching amount and the growth amount in the heating step S2 are, for example, in the range of 0.1 to 20 μm, but can be changed appropriately as necessary. Also, it can be understood that the etching amount and the growth amount are equivalent.

[0063] The etching rate in the heating step S2 and the growth rate of the growth layer 111 can be controlled by the above-mentioned temperature range, and can be set, for example, in the range of 0.001 to 2.0 μm / min.

[0064] The surface layer on the SiC single crystal substrate that is etched in the heating step S2 can be understood to be, for example, a damaged layer 300 containing scratches, latent scratches, distortions, etc., introduced through mechanical processing (e.g., slicing, grinding, and polishing) or laser processing.

[0065] <Separation process S3> Examples of the method for separating the substrate 13 in the separation step S3 include a multi-wire saw cutting method in which a plurality of wires are reciprocated to cut the substrate, an electric discharge machining method in which plasma discharge is intermittently generated to cut the substrate, a method for cutting the substrate 13 using a laser beam that is irradiated and focused into a crystal to form a layer that serves as a base point for cutting, etc. When the separation step S3 employs a method for cutting the substrate 13 using a laser beam, it is possible to reduce loss of material during separation of the substrate 13.

[0066] In the separation step S3, a part of the original substrate 11 having the growth layer 111 is separated to obtain a substrate 13 having the growth layer 111. The separation step S3 includes at least an introduction step S31 of introducing a damaged layer 300 into the original substrate 11, and a peeling step S32 of peeling off the substrate 13 from the damaged layer 300 as a starting point.

[0067] As shown in FIG. 3, in the introduction process S31, the focal point of laser light having a wavelength that is transparent to the original substrate 11 is positioned inside the original substrate 11 at a depth corresponding to the thickness of the substrate 13 to be separated from the upper surface, and the laser light is irradiated onto the original substrate 11 to form a damage layer 300.

[0068] 3, in the peeling step S32, the substrate 13 having the growth layer 111 is peeled off from the original substrate 11 along the damaged layer 300. The peeling step S32 can be exemplified by a method of adsorbing the front and back surfaces of the original substrate 11 to a pedestal or the like to separate them. In the peeling step S32, a thin wire is reciprocated along the damaged layer 300, or ultrasonic vibration is generated, thereby applying a conventional mechanical vibration to the original substrate 11, and the substrate 13 is peeled off from the original substrate 11 starting from the damaged layer 300.

[0069] The introduction step S31 and the peeling step S32 can appropriately employ at least a part of known techniques such as the methods described in, for example, JP 2013-49161 A, JP 2018-207034 A, JP 2017-500725 A, and JP 2017-526161 A. In addition, the introduction process S31 and the peeling process S32 can appropriately adopt at least a portion of publicly known techniques such as the methods described in patent documents such as JP-A-2017-526161, JP-A-2017-500725, JP-A-2018-152582, JP-A-2019-500220, and JP-A-2019-511122.

[0070] As described above, the original substrate 11 undergoes the setting step S1, the heating step S2, and the separation step S3 to manufacture the substrate 13 having the growth layer 111. By repeatedly carrying out the above steps, the substrate 13 having the growth layer 111 can be repeatedly manufactured. Furthermore, the above steps can be carried out again using the manufactured substrate 13 having the growth layer 111 as the original substrate 11.

[0071] Each of the original substrate 11 and the substrate 13 obtained through the setting step S1, the heating step S2, and the separation step S3 has a remaining damaged layer 300. Therefore, in one embodiment of the present invention, the original substrate 11 and the substrate 13 after the separation step S3 may be subjected to the heating step S2 including the etching step S23 to remove the remaining damaged layer 300 in the original substrate 11 and the substrate 13.

[0072] In one embodiment of the present invention, the setting step S1, the heating step S2, the setting step S1a, the heating step S2a, and the separation step S3 may be performed in this order. At this time, the setting step S1a sets the original substrate 11 and the raw material body 12 along the thickness direction of the original substrate 11 and the raw material body 12 so as to reverse the setting order of the original substrate 11 and the raw material body 12 set in the setting step S1. At this time, the heating step S2a heats the original substrate 11 and the raw material body 12 in the same manner as the heating step S2.

[0073] In one embodiment of the present invention, the placing step S1, the heating step S2, the heating step S2a, and the separation step S3 may be performed in this order. At this time, the heating step S2b heats the original substrate 11 and the source body 12 so as to reverse the temperature gradient formed along the thickness direction of the original substrate 11 and the source body 12. At this time, the heating step S2b heats the original substrate 11 and the source body 12 under the same temperature conditions, in the same atmosphere, and based on a source transport mechanism as the heating step S2.

[0074] Semiconductor substrate manufacturing equipment Hereinafter, this specification will explain in detail a semiconductor substrate manufacturing apparatus (hereinafter, simply referred to as a manufacturing apparatus) according to one embodiment of the present invention. Note that components that are basically the same as those in the configuration shown in the previous manufacturing method will be given the same reference numerals and their explanations will be simplified.

[0075] As shown in FIG. 4, the manufacturing apparatus includes a main container 20, a heating furnace 30, a high melting point container 40, and a separating means 50.

[0076] It can be understood that the original substrate 11 and the source material body 12 are alternately placed so that the original substrate 11 and the source material body 12 are spaced apart from each other by a predetermined distance 1112 .

[0077] The separation distance 1112 is preferably 10 mm or less, more preferably 7.0 mm or less, more preferably 5.0 mm or less, more preferably 4.0 mm or less, more preferably 3.0 mm or less, more preferably 2.0 mm or less, more preferably 1.7 mm or less, more preferably 1.5 mm or less, more preferably 1.2 mm or less, more preferably 1.0 mm or less, more preferably 700 μm or less, more preferably 500 μm or less, more preferably 200 μm or less, more preferably 100 μm or less, more preferably 70 μm or less, more preferably 50 μm or less, more preferably 20 μm or less, more preferably 10 μm or less, more preferably 7.0 μm or less, more preferably 5.0 μm or less, more preferably 2.0 μm or less, more preferably 1.0 μm or less, more preferably 0.7 μm or less, more preferably 0.5 μm or less, and more preferably 0.2 μm or less.

[0078] In addition, the separation distance 1112 is preferably 0.1 μm or more, more preferably 0.2 μm or more, more preferably 0.5 μm or more, more preferably 0.7 μm or more, more preferably 1.0 μm or more, more preferably 2.0 μm or more, more preferably 5.0 μm or more, more preferably 7.0 μm or more, more preferably 10 μm or more, more preferably 20 μm or more, more preferably 50 μm or more, more preferably 70 μm or more, more preferably 100 μm or more, more preferably 200 μm or more, more preferably 500 μm or more, more preferably 700 μm or more, more preferably 1.0 mm or more, more preferably 1.2 mm or more, more preferably 1.5 mm or more, more preferably 1.7 mm or more, more preferably 2.0 mm or more, more preferably 3.0 mm or more, more preferably 4.0 mm or more, more preferably 5.0 mm or more, and more preferably 7.0 mm or more.

[0079] Main body container 20 may include a conventional distance adjusting means 27, such as a spacer, for adjusting separation distance 1112. Distance adjusting means 27 is composed of the same atomic species as original substrate 11 and source body 12.

[0080] <Main container 20> As shown in FIG. 5, the main container 20 is a container in which the original substrate 11 and the source material 12 can be placed alternately. At this time, the original substrate 11 and the source material 12 are placed so as to be in close contact with each other. At this time, the main container 20 has a semi-closed space inside. Furthermore, when the main container 20 is heated, a vapor pressure of a gaseous species including the atomic species constituting the original substrate 11 is generated inside. At this time, there is no limit to the number of the original substrate 11 and the source material 12 placed by the main container 20. Note that the original substrate 11 and the source material 12 may be placed alternately in the order of the original substrate 11, the source material 12, and the original substrate 11, or may be placed alternately in the order of the source material 12, the original substrate 11, and the source material 12.

[0081] 6, main container 20 is a container in which original substrate 11 and raw material body 12 can be placed alternately. At this time, original substrate 11 and raw material body 12 are placed alternately so as to be spaced apart by distance 1112 by distance adjustment means 27. Note that original substrate 11 and raw material body 12 may be placed alternately in the order of original substrate 11, raw material body 12 and original substrate 11, or may be placed alternately in the order of raw material body 12, original substrate 11 and raw material body 12. Furthermore, main container 20 has a semi-closed space therein. When heated, main container 20 generates vapor pressure therein of gaseous species including atomic species that constitute original substrate 11. There is no limit to the number of original substrates 11 and source bodies 12 placed by main container 20.

[0082] 7, the main container 20 is a container in which a raw material transport prevention body 28 for preventing raw material transport between the original substrate 11 and the raw material body 12 between different unit processing bodies 1X including the original substrate 11 and the raw material body 12 can be installed. In this case, there is no limit to the respective numbers of the unit processing bodies 1X and the raw material transport prevention bodies 28 installed by the main container 20. Note that the original substrate 11 and the raw material body 12 may be installed alternately in the order of the original substrate 11, the raw material body 12, and the original substrate 11, or may be installed alternately in the order of the raw material body 12, the original substrate 11, and the raw material body 12. The raw material transport prevention body 28 is preferably a high-melting point metal such as W, Re, Os, Ta, Mo, etc., which will not be a source or destination of raw material transport between the above-mentioned original substrate 11 and raw material body 12, a carbide such as Ta9C8, HfC, TaC, NbC, ZrC, Ta2C, TiC, WC, MoC, etc., or a boride such as HfB2, TaB2, ZrB2, NB2, TiB2, etc.

[0083] As shown in FIG. 8, each of the multiple main containers 20 accommodates one original substrate 11. At this time, each of the multiple main containers 20 can be fitted to one another. At this time, the main container 20 has a semi-closed space inside. At this time, when the main container 20 is heated, a vapor pressure of a gaseous species including atomic species constituting the original substrate 11 is generated inside. At this time, there is no limit to the number of main containers 20 that accommodate one original substrate 11. Note that each of the multiple main containers 20 may be configured to accommodate the original substrate 11 and the source material 12.

[0084] Main body container 20 is made of, for example, a SiC material including SiC polycrystals. Therefore, at least a part of main body container 20 can be a source or destination of raw material body 12 in raw material transportation.

[0085] In one embodiment of the present invention, a main container in which at least the original substrate 11 and the source material body 12 can be placed alternately may be realized by appropriately combining at least a portion of the configurations in each of Figs.

[0086] The environment inside the heated main body container 20 is preferably a vapor pressure environment of a mixture of gaseous species containing Si element and gaseous species containing C element, for example. Examples of the gaseous species containing Si element include Si, Si2, Si3, Si2C, SiC2, and SiC. Examples of the gaseous species containing C element include Si2C, SiC2, SiC, and C.

[0087] The dopant and doping concentration of the main vessel 20 can be selected according to the dopant and doping concentration of the desired growth layer 111 or 121. An example of the dopant is N element.

[0088] Any structure may be adopted so long as it generates vapor pressure of a gaseous species containing Si element and a gaseous species containing C element in the internal space during heat treatment of main container 20. Examples include a structure in which SiC polycrystal is exposed on a part of the inner surface, and a structure in which SiC polycrystal is separately installed inside main container 20.

[0089] The main container 20 is, for example, a fitting container having an upper container 23 and a lower container 24 that can fit together. A minute gap 25 is formed at the fitting portion between the upper container 23 and the lower container 24, and the main container 20 is configured to be able to be evacuated (vacuumed) through this gap 25.

[0090] <Si vapor source 26> The main body vessel 20 includes a Si vapor supply source 26 (not shown in FIG. 4, but shown in FIG. 5). ). The Si vapor supply source 26 is used for the purpose of adjusting the atomic ratio Si / C in the semi-closed space in the main container 20 to exceed 1. Examples of the Si vapor supply source include solid Si (Si pellets such as Si pieces or Si powder) and Si compounds.

[0091] For example, in the case where main container 20 is entirely made of SiC polycrystal as in one embodiment of the present invention, by installing Si vapor source 26, the atomic ratio Si / C in main container 20 exceeds 1. Specifically, when original substrate 11 and source material 12, which satisfy a stoichiometric ratio of 1:1, and Si vapor source 26 are installed in main container 20 made of SiC polycrystal, which satisfies a stoichiometric ratio of 1:1, the atomic ratio Si / C in main container 20 exceeds 1.

[0092] The SiC-Si equilibrium vapor pressure environment according to one embodiment of the present invention is formed by heating a semi-closed space in which the atomic ratio Si / C exceeds 1. Also, the SiC-C equilibrium vapor pressure environment according to one embodiment of the present invention is formed by heating a semi-closed space in which the atomic ratio Si / C is 1 or less. The main body container 20 according to one embodiment of the present invention may be configured to appropriately accommodate predetermined members so as to create a SiC-Si equilibrium vapor pressure environment or a SiC-C equilibrium vapor pressure environment, respectively.

[0093] <Heating furnace 30> The heating furnace 30 is configured to heat so as to form a temperature gradient such that the temperature decreases / increases from the upper container 23 to the lower container 24 of the main container 20. As a result, a temperature gradient is formed in the thickness direction of the original substrate 11.

[0094] As shown in FIG. 4, the heating furnace 30 is equipped with a main heating chamber 31 capable of heating the workpiece (such as the original substrate 11, main container 20, high-melting point container 40, etc.) to a temperature of 1000°C or more and 2300°C or less, a preliminary chamber 32 capable of preheating the workpiece to a temperature of 500°C or more, a high-melting point container 40 capable of accommodating the main container 20, and a moving means 33 (moving table) capable of moving the high-melting point container 40 from the preliminary chamber 32 to the main heating chamber 31.

[0095] The main heating chamber 31 is formed into a regular hexagon in a plan cross-sectional view, and a high melting point container 40 is placed inside the main heating chamber 31. A heater 34 (mesh heater) is provided inside the main heating chamber 31. In addition, a multi-layer heat reflecting metal plate is fixed to the side walls and ceiling of the main heating chamber 31 (not shown). The multi-layer heat reflecting metal plate is configured to reflect heat from the heater 34 toward approximately the center of the main heating chamber 31.

[0096] The heater 34 is installed in the main heating chamber 31 so as to surround the high melting point container 40 in which the object to be treated is accommodated. At this time, a multi-layer heat reflecting metal plate is installed on the outside of the heater 34, so that the temperature can be raised in the range of 1000°C to 2300°C.

[0097] The heater 34 may be, for example, a resistance heating type heater or a high-frequency induction heating type heater.

[0098] The heater 34 may be configured to be capable of forming a temperature gradient within the high-melting-point container 40 . For example, the heater 34 may be configured so that more heaters are installed on the upper side (or lower side). The heater 34 may be configured so that the width increases toward the upper side (or lower side). Alternatively, the heater 34 may be configured so that the power supplied to it can be increased toward the upper side (or lower side). The heater 34 may be capable of reversing the direction of the temperature gradient.

[0099] Connected to the main heating chamber 31 are a vacuum forming valve 35 for evacuating the inside of the main heating chamber 31, an inert gas injection valve 36 for introducing an inert gas into the main heating chamber 31, and a vacuum gauge 37 for measuring the degree of vacuum inside the main heating chamber 31.

[0100] The vacuum forming valve 35 is connected to a vacuum pump (not shown) that evacuates the inside of the main heating chamber 31 to create a vacuum. By using the vacuum forming valve 35 and the vacuum pump, the degree of vacuum in the main heating chamber 31 is preferably 10 Pa or less, more preferably 1.0 Pa or less, and most preferably 10 -3 The pressure can be adjusted to be equal to or less than Pa. An example of the vacuum pump is a turbo molecular pump.

[0101] The inert gas injection valve 36 is connected to an inert gas supply source (not shown). The inert gas is injected into the heating chamber 31 by the inert gas injection valve 36 and the inert gas supply source. -5 ~10 4 The inert gas can be introduced in the range of Pa. As the inert gas, Ar or the like can be selected.

[0102] The inert gas injection valve 36 is a dopant gas supplying means capable of supplying a dopant gas into the main body container 20. That is, by selecting a dopant gas (for example, N2 or the like) as the inert gas, the doping concentration of the growth layer 111 can be increased.

[0103] The preliminary chamber 32 is connected to the main heating chamber 31, and is configured so that the high melting point container 40 can be moved by a moving means 33. The preliminary chamber 32 in this embodiment is configured so that it can be heated by the residual heat of the heater 34 of the main heating chamber 31. For example, when the main heating chamber 31 is heated to 2000°C, the preliminary chamber 32 is heated to about 1000°C, and the degassing process of the workpiece can be performed.

[0104] The moving means 33 is configured to be capable of moving the high melting point container 40 between the main heating chamber 31 and the preliminary chamber 32 with the high melting point container 40 placed thereon.

[0105] The transfer between the main heating chamber 31 and the preliminary chamber 32 by the moving means 33 can be completed in as little as one minute, so that it is possible to realize a temperature increase / decrease rate of 1.0 to 1000°C / min. This allows for rapid temperature increase and decrease, making it possible to observe a surface shape that does not have a low-temperature growth history during temperature increase and decrease. In addition, although the preliminary chamber 32 is installed below the main heating chamber 31 in FIG. 4, the preliminary chamber 32 is not limited to this and may be installed in any direction.

[0106] The moving means 33 according to this embodiment is a moving stage on which the high melting point container 40 is placed. The contact portion between this moving stage and the high melting point container 40 serves as a heat transfer path. This allows a temperature gradient to be formed in the high melting point container 40 such that the contact portion between the moving stage and the high melting point container 40 is the low temperature side.

[0107] In the heating furnace 30 of this embodiment, since the bottom of the high melting point container 40 is in contact with the moving stage, a temperature gradient is provided such that the temperature decreases from the upper container 41 to the lower container 42 of the high melting point container 40 .

[0108] The direction of the temperature gradient can be set to any direction by changing the position of the contact part between the moving stage and the high melting point container 40. For example, if a hanging type moving stage is used and the contact part is provided on the ceiling of the high melting point container 40, heat escapes upward. Therefore, the temperature gradient is provided such that the temperature increases from the upper container 41 to the lower container 42 of the high melting point container 40. Note that this temperature gradient is preferably formed along the thickness direction of the original substrate 11 and the source material 12. Also, as described above, the temperature gradient may be formed by the configuration of the heater 34.

[0109] <High melting point container 40> The vapor pressure environment of the gaseous species containing Si element in the heating furnace 30 according to this embodiment is formed by using a high melting point container 40 and a Si vapor supply material 44. For example, any method capable of forming an environment of the vapor pressure of the gaseous species containing Si element around the main container 20 can be adopted in the semiconductor substrate manufacturing apparatus of the present invention.

[0110] The high melting point container 40 is preferably configured to include a high melting point material having a melting point equal to or higher than the melting point of the material that constitutes the main container 20 .

[0111] Examples of high-melting point container 40 include general-purpose heat-resistant material C, high-melting point metals W, Re, Os, Ta, Mo, carbides Ta9C8, HfC, TaC, NbC, ZrC, Ta2C, TiC, WC, MoC, nitrides HfN, TaN, BN, Ta2N, ZrN, TiN, borides HfB2, TaB2, ZrB2, NB2, TiB2, polycrystalline SiC, etc.

[0112] 5, the high melting point container 40, like the main container 20, is a fitting container including an upper container 41 and a lower container 42 that can fit together, and is configured to be able to accommodate the main container 20. A minute gap 43 is formed at the fitting portion between the upper container 41 and the lower container 42, and is configured so that the inside of the high melting point container 40 can be evacuated (vacuumed) through this gap 43.

[0113] The high-melting-point vessel 40 contains a Si vapor supplying material 44 capable of supplying a vapor pressure of a gaseous species containing elemental Si into the high-melting-point vessel 40 .

[0114] <Si vapor supply material 44> The Si vapor supply material 44 may be any material that generates Si vapor in the high-melting point container 40 during heat treatment, and examples thereof include solid Si (Si pellets such as Si pieces or Si powder) and Si compounds.

[0115] The Si vapor supply material 44 is illustratively a thin film that coats the inner wall of the high melting point vessel 40 .

[0116] When the high melting point vessel 40 is a metal compound such as TaC, the Si vapor supply material 44 is, for example, a silicide material of metal atoms and Si atoms that constitute the high melting point vessel 40 .

[0117] <Separation means> The separating means 50 separates a part of the original substrate 11 having the growth layer 111 to obtain a substrate 13 having the growth layer 111 . The separating means 50 includes at least an introducing means 51 for introducing a damaged layer 300 into the original substrate 11, and a peeling means 52 for peeling off the substrate 13 from the damaged layer 300 as a starting point.

[0118] As shown in FIG. 3 , the introduction means 51 positions the focal point of laser light having a wavelength that is transparent to the growth layer 111 and the original substrate 11 inside the original substrate 11 at a depth corresponding to the thickness of the substrate 13 to be separated from the upper surface, and irradiates the laser light onto the original substrate 11 to form a damaged layer 300.

[0119] The introduction means 51 includes a holding means (not shown) capable of holding the original substrate 11 and the raw material body 12 based on a conventional technique such as an adsorption chuck, an oscillation means 511 which is a light source capable of irradiating pulsed laser light, and a conventional focusing means 512 such as a lens capable of focusing the laser light, and is capable of scanning at least a portion of the oscillation means 511 and the focusing means 512. In addition, at least a part of each device constituting the introduction means 51 has a conventional adjustment means capable of aligning in any axial direction. There is no limitation on the wavelength, time width, output, spot diameter, etc. of the laser light.

[0120] As shown in FIG. 3, the peeling means 52 peels off the substrate 13 having the growth layer 111 from the original substrate 11 along the damaged layer 300 . The peeling means 52 may be, for example, a method of adsorbing the front and back surfaces of the original substrate 11 to a pedestal or the like to separate them. In addition, the peeling means 52 applies conventional mechanical vibrations to the original substrate 11 by, for example, reciprocating a thin wire along the damaged layer 300 or generating ultrasonic vibrations, and peels off the substrate 13 from the original substrate 11 starting from the damaged layer 300.

[0121] The peeling means 52 has a high melting point container for peeling capable of accommodating the original substrate 11, and holding means capable of holding the original substrate 11 by a conventional method such as an adsorption chuck. The peeling means 52 also has vibration means capable of generating conventional mechanical vibrations including ultrasonic vibrations and applying the mechanical vibrations to the original substrate 11, and liquid supply means capable of supplying liquid such as pure water based on a conventional method.

[0122] The introduction means 51 and the peeling means 52 can be appropriately made of devices and the like for realizing known techniques. The introduction means 51 and the peeling means 52 may each appropriately adopt at least a portion of the devices described in, for example, JP 2013-49161 A, JP 2018-207034 A, JP 2017-500725 A, JP 2017-526161 A, etc. Furthermore, each of the introduction means 51 and the peeling means 52 can appropriately adopt at least a portion of the devices described in patent documents such as, for example, JP-T-2017-526161, JP-T-2017-500725, JP-A-2018-152582, JP-T-2019-500220, and JP-T-2019-511122.

[0123] As described above, the substrate 13 having the growth layer 111 is manufactured by subjecting the original substrate 11 to the processes in the main container 20, the heating furnace 30, and the separating means 50. The process may be repeated to repeatedly manufacture the substrate 13 having the growth layer 111. The process may also be performed using the substrate 13 having the growth layer 111 as a new original substrate 11.

[0124] This specification will explain the effects of the present invention with reference to Reference Examples 1 to 3. 《Reference example 1》 Under the following conditions, the SiC single crystal substrate E10 is housed in a main body container 20, and the main body container 20 is housed in a high-melting point container 40.

[0125] <SiC single crystal substrate E10> Polymorphism: 4H-SiC Board size: width (10mm), length (10mm), thickness (0.3mm) Off direction and off angle: 4° off in the <11-20> direction Growth plane: (0001) plane MSB: None Damage layer: None

[0126] <Main container> Material: SiC polycrystalline Container size: diameter (60 mm), height (4.0 mm) Distance between SiC single crystal substrate E10 and SiC material: 2.0 mm Atomic ratio inside the container: Si / C: 1 or less

[0127] <High melting point container> Material: TaC Container size: diameter (160mm), height (60mm) Si vapor supply material 44 (Si compound): TaSi2

[0128] The SiC single crystal substrate E10 placed under the above conditions was heat-treated under the following conditions. Heating temperature: 1700℃ Heating time: 300min Temperature gradient: 1.0℃ / mm Growth rate: 5.0nm / min Vacuum degree of main heating chamber 31: 10 -5 Pa

[0129] FIG. 9 is an explanatory diagram of a method for determining the conversion rate of BPDs into other defects / dislocations (TEDs, etc.) in the growth layer E11.

[0130] 9(a) shows the state where the growth layer E11 is grown by a heating process. In this heating process, the BPDs present in the SiC single crystal substrate E10 are converted to TEDs with a certain probability. Therefore, unless 100% is converted, TEDs and BPDs will be mixed on the surface of the growth layer E11.

[0131] Fig. 9(b) shows the state where defects in the growth layer E11 were confirmed using the KOH dissolution etching method. This KOH dissolution etching method is a method in which the SiC single crystal substrate E10 is immersed in molten salt (KOH, etc.) heated to about 500°C, etch pits are formed at dislocations and defects, and the type of dislocation is identified based on the size and shape of the etch pits. By this method, the number of BPDs present on the surface of the growth layer E11 is evaluated.

[0132] FIG. 9(c) shows the growth layer E11 being removed after KOH dissolution etching. In this method, the surface of the SiC single crystal substrate E10 is exposed by planarizing the surface to the depth of the etch pits by mechanical polishing, CMP, or the like, and then removing the growth layer E11 by thermal etching.

[0133] 9(d) shows the state in which defects in the SiC single crystal substrate E10 from which the growth layer E11 has been removed are confirmed using a KOH dissolution etching method. By this method, the number of BPDs present on the surface of the SiC single crystal substrate E10 is evaluated.

[0134] By comparing the number of BPDs present on the surface of the growth layer E11 (see FIG. 9(b)) with the number of BPDs present on the surface of the SiC single crystal substrate E10 (see FIG. 9(d)) using the series of steps shown in FIG. 9, the BPD conversion rate of BPDs converted to other defects and dislocations during the heating step S2 can be obtained.

[0135] The number of BPDs present on the surface of the growth layer E11 in Reference Example 1 was approximately 0 / cm -2 The number of BPDs present on the surface of the SiC single crystal substrate E10 is 1000 cm -2 In other words, it can be understood that BPDs are reduced or eliminated by placing the SiC single crystal substrate E10, which does not have MSB on its surface, in a semi-closed space with an atomic ratio of Si / C of 1 or less and heating it.

[0136] In Reference Example 1, a SiC-C equilibrium vapor pressure environment is formed within main container 20 so that the atomic ratio Si / C within main container 20 is equal to or less than 1. Since the heating step S2 including the etching step S23 in the above method and the heating step S2 including the etching step according to one embodiment of the present invention are based on the same elementary reaction process, it can be understood that BPDs can also be reduced or removed in the etching step according to one embodiment of the present invention.

[0137] 《Reference example 2》 Under the following conditions, the SiC single crystal substrate E10 was housed in the main container 20, and the main container 20 was further housed in the high-melting point container 40.

[0138] <SiC single crystal substrate E10> Polymorphism: 4H-SiC Board size: width (10mm), length (10mm), thickness (0.3mm) Off direction and off angle: 4° off in the <11-20> direction Growth plane: (0001) plane MSB: Yes

[0139] <Main container> Material: SiC polycrystalline Container size: diameter (60 mm), height (4.0 mm) Distance between SiC single crystal substrate E10 and SiC material: 2.0 mm Si vapor source 26: Si piece The atomic ratio of Si / C in the container exceeds 1.

[0140] By accommodating a Si piece together with a SiC single crystal substrate in main container 20, the atomic ratio Si / C in the container exceeds 1.

[0141] <High melting point container> Material: TaC Container size: diameter 160mm x height 60mm Si vapor supply material 44 (Si compound): TaSi2

[0142] The SiC single crystal substrate E10 placed under the above conditions was heat-treated under the following conditions. Heating temperature: 1800℃ Heating time: 60min Temperature gradient: 1.0℃ / mm Growth rate: 68nm / min Main heating chamber 31 degree of vacuum: 10 -5 Pa

[0143] Figure 10 is an SEM image of the surface of the SiC single crystal substrate E10 before the growth of the growth layer E11. Figure 10(a) is an SEM image observed at a magnification of x1000, and Figure 10(b) is an SEM image observed at a magnification of x100,000. It can be seen that MSBs are formed on the surface of the SiC single crystal substrate E10 before the growth of the growth layer E11, and steps with a height of 3.0 nm or more are arranged with an average terrace width of 42 nm. The step height was measured by AFM.

[0144] Fig. 11 shows SEM images of the surface of the SiC single crystal substrate E10 after the growth of the growth layer E11. Fig. 11(a) is an SEM image observed at a magnification of ×1000, and Fig. 11(b) is an SEM image observed at a magnification of ×100,000. It can be seen that no MSB is formed on the surface of the growth layer E11 of Reference Example 2, and steps of 1.0 nm (full unit cell) are regularly arranged with a terrace width of 14 nm. The step height was measured by AFM.

[0145] Therefore, it can be understood that by placing a SiC single crystal substrate E10 having MSB on its surface in a quasi-closed space with an atomic ratio Si / C exceeding 1 and heating it, a growth layer E11 in which the MSB is decomposed is formed.

[0146] In Reference Example 2, Si vapor supply source 26 is installed so that atomic ratio Si / C in main container 20 exceeds 1, and therefore a SiC-Si equilibrium vapor pressure environment is formed in main container 20. Since the heating step S2 including the etching step S23 in the above-described method and the heating step including the etching step according to one embodiment of the present invention are based on the same elementary reaction process, it can be understood that the MSB on the surface of the SiC single crystal substrate can also be decomposed in the etching step according to one embodiment of the present invention.

[0147] 《Reference example 3》 12 is a graph showing the relationship between the heating temperature and the growth rate when grown by the manufacturing method of the SiC single crystal substrate according to the present invention. The horizontal axis of this graph is the reciprocal of the temperature, and the vertical axis of this graph is the logarithmic growth rate. The result of placing the SiC single crystal substrate E10 in a space (inside the main body container 20) where the atomic ratio Si / C exceeds 1 and growing the growth layer E11 on the SiC single crystal substrate E10 is shown by a circle. Also, the result of placing the SiC single crystal substrate E10 in a space (inside the main body container 20) where the atomic ratio Si / C is 1 or less and growing the growth layer E11 on the SiC single crystal substrate E10 is shown by a cross.

[0148] In addition, the graph in FIG. 12 shows the results of thermodynamic calculations of SiC substrate growth in a SiC-Si equilibrium vapor pressure environment using a dashed line (Arrhenius plot), and shows the results of thermodynamic calculations of SiC substrate growth in a SiC-C equilibrium vapor pressure environment using a two-dot chain line (Arrhenius plot).

[0149] In this method, under conditions where the vapor pressure environment between the SiC raw material and the SiC substrate is a SiC-C equilibrium vapor pressure environment or a SiC-C equilibrium vapor pressure environment, the SiC single crystal substrate E10 is grown using a chemical potential difference or a temperature gradient as a growth driving force. An example of this chemical potential difference is the partial pressure difference between the gas phase species generated on the surfaces of the SiC polycrystal and the SiC single crystal.

[0150] Here, when the growth amount is the partial pressure difference between the vapor generated from the SiC raw material (transport source) and the SiC substrate (transport destination), the SiC growth rate can be calculated by the following equation 1.

[0151]

number

[0152] Here, T is the temperature of the SiC raw material side, m i is a gas phase species (Si x C y ) is the molecular weight of the molecule, and k is the Boltzmann constant. 輸送元i -P 輸送先i is the amount of SiC deposited when the source gas becomes supersaturated, and the source gas is assumed to be SiC, Si2C, or SiC2.

[0153] Therefore, the broken line is the result of thermodynamic calculation when growing a SiC single crystal using a SiC polycrystal as a raw material in a vapor pressure environment when SiC (solid) and Si (liquid phase) are in phase equilibrium via the gas phase. Specifically, the result was obtained by thermodynamic calculation using Equation 1 under the following conditions (i) to (iv). (i) A constant volume SiC-Si equilibrium vapor pressure environment (ii) The driving force for growth is the temperature gradient within the main vessel 20 and the vapor pressure difference (chemical potential difference) between the SiC polycrystal and the SiC single crystal. (iii) The raw gas is SiC, Si2C, or SiC2. (iv) The adsorption coefficient of the raw material adsorbed to the steps of the SiC single crystal substrate E10 is 0.001.

[0154] The two-dot chain line is the result of a thermodynamic calculation when a SiC single crystal is grown using a SiC polycrystal as a raw material in a vapor pressure environment when SiC (solid phase) and C (solid phase) are in phase equilibrium via the gas phase. Specifically, the result was obtained by thermodynamic calculation using Equation 1 under the following conditions (i) to (iv). (i) A constant volume SiC-C equilibrium vapor pressure environment (ii) The growth driving force is the temperature gradient in the main vessel 20 and the vapor pressure difference (chemical potential difference) between the SiC polycrystal and the SiC single crystal. (iii) The raw gas is SiC, Si2C, or SiC2. (iv) The adsorption coefficient of the raw material adsorbed to the steps of the SiC single crystal substrate E10 is 0.001. The data for each chemical species used in the thermodynamic calculations were taken from the JANAF Thermochemical Tables.

[0155] 12, it can be understood that the result (marked with a circle) of growing a growth layer E11 on the SiC single crystal substrate E10 by placing the SiC single crystal substrate E10 in a space (inside the main container 20) where the atomic ratio Si / C exceeds 1 matches the trend of the thermodynamic calculation result of SiC growth in a SiC-Si equilibrium vapor pressure environment. Also, it can be understood that the result (marked with a cross) of growing a growth layer E11 on the SiC single crystal substrate E10 by placing the SiC single crystal substrate E10 in a space (inside the main container 20) where the atomic ratio Si / C is 1 or less matches the trend of the thermodynamic calculation result of SiC growth in a SiC-C equilibrium vapor pressure environment.

[0156] It can be understood that in a SiC-Si equilibrium vapor pressure environment, a growth rate of 1.0 μm / min or more is achieved at a heating temperature of 1960°C. It can also be understood that a growth rate of 2.0 μm / min or more is achieved at a heating temperature of 2000°C or higher. On the other hand, in a SiC-C equilibrium vapor pressure environment, it can be understood that a growth rate of 1.0 μm / min or more is achieved at a heating temperature of 2000°C. It can also be understood that a growth rate of 2.0 μm / min or more is achieved at a heating temperature of 2030°C or higher.

[0157] According to the present invention, it is possible to provide a novel technique capable of growing high-quality semiconductor substrates by simultaneously achieving desired growth conditions for each of a plurality of original substrates. [Explanation of symbols]

[0158] 1X: Unit processing unit 11: Original board 12: Raw material body 13: Substrate 20: Main container 27: Distance adjustment means 28: Raw material transport prevention body 30:Heating furnace 40: High melting point container 50: Separation means 51: Means of introduction 52: Peeling means 111: Growth layer 300: Damage layer 511: Oscillation means 512: Light collecting means 1112: Separation distance S1: Installation process S2: Heating process S21:Si atom sublimation process S22:C atom sublimation process S23: Etching process S24: Growth process S3: Separation process S31:Introduction process S32: Peeling process

Claims

1. The method includes a step of stacking and placing an original substrate and a source body in a quasi-closed space so that the original substrate and the source body are alternately in contact with each other, and a step of heating the original substrate and the source body so that a temperature gradient is formed along a thickness direction of the original substrate and the source body to form a growth layer on the original substrate, The method for producing a semiconductor substrate, wherein the original substrate and the source body are SiC single crystals.

2. The method according to claim 1 , further comprising a step of separating a portion of the original substrate having the growth layer.

3. 3. The method according to claim 2, wherein the separating step includes an introducing step of introducing a damage layer into the original substrate having the growth layer, and a peeling step of peeling off a part of the original substrate having the growth layer.

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