Method for manufacturing a self-supporting substrate

Abstract

The present invention relates to a method for manufacturing a self-supporting substrate. [Solution] A method for manufacturing a self-supporting substrate of the present invention includes the steps of forming a thin film bottom, the thin film bottom including a first substrate layer, a thin film layer, and a second substrate layer stacked in order, peeling the first substrate layer from the thin film layer, forming a thick film layer by growing the same material as the thin film layer on one side of the thin film layer away from the second substrate layer, and peeling the second substrate layer from the thick film layer to retain the thick film layer. The method for manufacturing a self-supporting substrate of the present invention allows a thin film to be grown on a substrate with a large diameter, and the thin film thickness prevents tearing of the thin film and / or the substrate. This allows for the production of thin films with very large diameters and large-sized self-supporting substrates.

Description

[Technical Field]

[0001] The present invention is in the field of semiconductor technology and specifically relates to a method for manufacturing a self-supporting substrate. [Background technology]

[0002] Research and applications of GaN materials are currently attracting attention in the semiconductor field. GaN materials are a new type of semiconductor material for manufacturing microelectronic devices and optoelectronics. GaN materials, along with semiconductor materials such as SiC and diamond, are considered third-generation semiconductor materials, following the first-generation Ge and Si semiconductor materials and the second-generation GaAs and InP compound semiconductor materials. GaN materials possess properties such as a wide direct band gap, strong atomic bonds, high thermal conductivity, high chemical stability (resistant to corrosion by all acids), and strong irradiation resistance, making them widely used in optoelectronics, high-temperature high-power components, and high-frequency microwave devices. GaN materials are widely used in various fields, such as LEDs, base station power amplifiers, and consumer electronics chargers.

[0003] In the case of GaN materials, the lack of a single-crystal substrate results in a very high heteroepitaxial defect density. There are three methods for obtaining GaN single-crystal substrates. The first method is to produce GaN single crystals by directly reacting nitrogen and metallic gallium at high temperature and pressure. The second method is to grow GaN single crystals at low temperature and under nitrogen pressure using a fluxing agent. The third method is to grow a thick GaN film on a foreign substrate using hydride vapor phase epitaxy (HVPE) and then peel the thick film from the foreign substrate to obtain a self-supporting GaN substrate. Due to drawbacks of these two methods, it is difficult to easily obtain large-sized single-crystal substrates. Commercially available GaN single-crystal substrates are manufactured using HVPE technology, which has a simple structure, low cost, and allows for rapid growth. Since HVPE technology uses a heterogeneous substrate, the size of the obtained GaN single crystal substrate is determined by the size of the heteroepitaxial substrate, such as sapphire, SiC, or silicon substrate, and large-sized single crystal substrates can be easily obtained. In particular, GaN self-supporting substrate technology using sapphire substrates has been widely applied in various fields.

[0004] Two problems must be overcome when fabricating self-supporting GaN substrates on sapphire substrates using the currently used HVPE technology. The first problem is the lattice mismatch and thermal mismatch between the sapphire and GaN substrates. When the size of the GaN epitaxial film reaches several tens of micrometers, stress can cause the epitaxial film to tear, significantly affecting the yield rate when fabricating large-scale self-supporting GaN substrates. The second problem is the method for separating the thick GaN film from the substrate. The widespread use of various insertion layer technologies and graphic mask processes, along with the filing of numerous patents, can reduce the risk of epitaxial film tearing due to lattice mismatch and improve crystal quality. For examples of such technologies, see patents issued by Sumitomo Electric Industries, Ltd. of Japan.

[0005] We are currently researching the production of gallium nitride substrates using MOCVD (Metal-organic Chemical Vapor Deposition) and HVPE. First, a 0.1-1 micrometer crystal layer is grown on a sapphire substrate using MOCVD. Next, a 300 micrometer gallium nitride substrate is grown using HVPE, after which the original substrate is peeled off and burnished. After growing a nucleation layer on the sapphire substrate using HVPE in a low-temperature environment, a GaN thick film with a certain thickness can be grown at high temperatures.

[0006] However, due to lattice and thermal mismatches, when the gallium nitride reaches a certain thickness, the substrate bends into an arc, significantly affecting the yield rate of the substrate. The resulting thick film bends, necessitating mechanical polishing to flatten it. Furthermore, large thick films cannot be easily grown, and the resulting bending can cause the substrate to lose support, potentially resulting in the film tearing. While current solutions allow for the growth of thick films on 4-inch or 6-inch substrates, larger sapphire substrates, such as 8-inch or 10-inch sapphire substrates, cannot withstand the bending caused by this method. Summary of the Invention [Problem to be solved by the invention]

[0007] In order to solve the technical problems of the prior art, the present invention provides the following method for manufacturing a self-supporting substrate: The present invention can solve the technical problems of the prior art through the following technical points. [Means for solving the problem]

[0008] The method of manufacturing a self-supporting substrate of the present invention comprises: forming a thin film bottom, the thin film bottom including a first substrate layer, a thin film layer, and a second substrate layer stacked in sequence; peeling the first substrate layer from the thin film layer; a surface of the thin film layer that is away from the second substrate layer and a same forming a thick film layer by growing a material; peeling the second substrate layer from the thick film layer, retaining the thick film layer.

[0009] In any one embodiment of the present invention, forming the thin film bottom portion comprises: selecting a first substrate layer; A thin film is formed on the first substrate layer. layer forming a growing a second substrate layer on one side of the thin film layer remote from the first substrate layer.

[0010] In any one embodiment of the present invention, growing a second substrate layer on one side of the thin film layer away from the first substrate layer comprises: selecting a second substrate layer; bonding the thin film layer and the second substrate layer together; Includes:

[0011] In any one embodiment of the present invention, bonding the thin film layer and the second substrate layer together includes: adhering the thin film layer and the second substrate layer together with an adhesive layer; bonding the thin film layer and the second substrate layer together by a wafer bonding method; Includes:

[0012] In any one embodiment of the present invention, the adhesive layer includes a first adhesive layer and a second adhesive layer; Adhering the thin film layer and the second substrate layer together with an adhesive layer comprises: forming a first adhesive layer on the thin film layer; forming a second adhesive layer on the second substrate layer; bonding the thin film layer and the second substrate layer together with the first adhesive layer and the second adhesive layer; Includes:

[0013] In any one embodiment of the present invention, peeling the first substrate layer from the thin film layer includes peeling the first substrate layer from the thin film layer by a laser peeling method or a chemical etching method.

[0014] In one embodiment of the present invention, a surface of the thin film layer that is away from the second substrate layer is provided with a material of the thin film layer. same Forming a thick layer by growing a material a surface of the thin film layer that is separated from the second substrate layer by MOCVD or HVPE and a material of the thin film layer; same The method includes growing a material to form a thick layer.

[0015] In any one embodiment of the present invention, the second substrate layer is Thickness The peeling step may include peeling the second substrate layer from the film layer by a chemical etching method. Thickness The method includes the step of peeling the film layer.

[0016] In any one embodiment of the present invention, the materials of the second substrate layer and the thin film layer are , both GaN-based It is a material.

[0017] In any one embodiment of the present invention, the material of the thin film layer is a GaN-based material. [Effects of the Invention]

[0018] The present invention can provide the following advantageous effects. The method for fabricating a self-supporting substrate of the present invention allows for the growth of thin films on large diameter substrates, and the thin film thickness prevents tearing of the film and / or the substrate, thereby enabling the achievement of very large diameter thin films and large sized self-supporting substrates.

[0019] The present invention will be described in more detail below with reference to the drawings and examples. [Brief explanation of the drawings]

[0020] [Figure 1] 3 is a flow chart illustrating a method for manufacturing a self-supporting substrate according to an embodiment of the present invention. [Figure 2a] 1A to 1C are diagrams illustrating steps in a method for manufacturing a self-supporting substrate according to an embodiment of the present invention. [Figure 2b] 1A to 1C are diagrams illustrating steps in a method for manufacturing a self-supporting substrate according to an embodiment of the present invention. [Figure 2c] 1A to 1C are diagrams illustrating steps in a method for manufacturing a self-supporting substrate according to an embodiment of the present invention. [Figure 2d] 1A to 1C are diagrams illustrating steps in a method for manufacturing a self-supporting substrate according to an embodiment of the present invention. [Figure 2e] 1A to 1C are diagrams illustrating steps in a method for manufacturing a self-supporting substrate according to an embodiment of the present invention. [Figure 2f] 1A to 1C are diagrams illustrating steps in a method for manufacturing a self-supporting substrate according to an embodiment of the present invention. [Figure 2g] 1A to 1C are diagrams illustrating steps in a method for manufacturing a self-supporting substrate according to an embodiment of the present invention. [Figure 2h] 1A to 1C are diagrams illustrating steps in a method for manufacturing a self-supporting substrate according to an embodiment of the present invention. [Figure 2i] 1A to 1C are diagrams illustrating steps in a method for manufacturing a self-supporting substrate according to an embodiment of the present invention. [Figure 3a] 3A to 3C are diagrams illustrating steps of forming a thin film layer in a method for manufacturing a self-supporting substrate according to an embodiment of the present invention. [Figure 3b] 3A to 3C are diagrams illustrating steps of forming a thin film layer in a method for manufacturing a self-supporting substrate according to an embodiment of the present invention. [Figure 3c] 3A to 3C are diagrams illustrating steps of forming a thin film layer in a method for manufacturing a self-supporting substrate according to an embodiment of the present invention. [Figure 3d]3A to 3C are diagrams illustrating steps of forming a thin film layer in a method for manufacturing a self-supporting substrate according to an embodiment of the present invention. [Figure 3e] 3A to 3C are diagrams illustrating steps of forming a thin film layer in a method for manufacturing a self-supporting substrate according to an embodiment of the present invention. [Figure 3f] 3A to 3C are diagrams illustrating steps of forming a thin film layer in a method for manufacturing a self-supporting substrate according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] The present invention will be described in more detail below with reference to specific examples, but the present invention is not limited to the following examples.

[0022] <Example 1> Referring to Figure 1, Figure 1 is a flow chart showing a method for manufacturing a self-supporting substrate according to an embodiment of the present invention. In this embodiment, a method for manufacturing a self-supporting substrate is provided, and the method for manufacturing a self-supporting substrate includes the following steps:

[0023] In step 1, a thin film bottom is formed, which includes a first substrate layer, a thin film layer, and a second substrate layer, which are stacked in order.

[0024] Referring to FIG. 2a, in step 1.1 a first substrate layer 10 is selected.

[0025] The first substrate layer 10 can be silicon (Si), silicon carbide (SiC), diamond, sapphire (Al2O3), gallium arsenide (GaAs), aluminum nitride (AlN), gallium nitride (GaN), metal, metal oxide, compound semiconductor, glass, quartz, or a composite material, etc.

[0026] Preferably, the material of the first substrate layer 10 is sapphire.

[0027] Referring to FIG. 2b, in step 1.2, a thin film is formed on the first substrate layer 10. layer Form 11.

[0028] The material of the thin film layer in this example is 、 III-V tribe The thin film layer may be made of a compound semiconductor material. Specifically, the thin film layer may be made of a GaN-based material. The GaN-based material may be GaN, Al x Ga 1-x N(0≦x<1, x<0.5), In x Ga 1-x N(0≦x<1, x<0.5) and Al x Ga y In 1-x-y N( 0≦x<y、y> 1-xy, x+y<1 ) Semiconductor material represented by the formula The thickness of the thin film layer 11 is 10 μm.

[0029] The GaN-based material can be undoped, N-type doped or P-type doped material.

[0030] In the growth method of GaN-based materials, deposition can be carried out using single doped or undoped material, or using a combination of undoped and doped steps, or using a combination of N-type and P-type doping.

[0031] The thickness of the thin film layer 11 ranges from 0.1 μm to 20 μm.

[0032] This embodiment does not limit the specific method for forming the thin film layer 11 on the first substrate layer 10. Those skilled in the art can form the thin film layer 11 on the first substrate layer 10 using an appropriate manufacturing method. It should be noted that FIG. 2b illustrates the positional relationship between the first substrate layer 10 and the thin film layer 11 in this embodiment, but does not limit the structures of the first substrate layer 10 and the thin film layer 11. For example, the thin film layer 11 can be grown on the first substrate layer 10 by chemical vapor deposition (MOCVD) or by forming a support structure on the first substrate layer 10 to support the thin film layer 11. To explain this embodiment in more detail, this embodiment will use a specific example to describe a manufacturing method for the thin film layer 11 having the support structure. The manufacturing method can include steps 1.211 to 1.212.

[0033] In step 1.211, a plurality of seed crystals are formed on the first substrate layer 10. Each seed crystal is spaced apart from one another on the first substrate layer 10. Holes are formed between the seed crystals, and each hole is connected to the other in a communicating state.

[0034] In this embodiment, a plurality of seed crystals are formed on the first substrate layer 10 through steps 1.21111 to 1.21113. In step 1.21111, a plurality of protruding structures and a plurality of recessed structures are formed on the surface of the first substrate layer 10 by a patterning method.

[0035] Specifically, the method for forming a plurality of protruding structures and a plurality of recessed structures on the first substrate layer 10 may include the following steps 1.21111 to 1.21113. Referring to FIG. 3 a, in step 1.21111, a mask layer 111 is formed on a first substrate layer 10 .

[0036] Referring to Figure 3b, in step 1.21112, a portion of the surface of the first substrate layer 10 is exposed by exposing, developing and etching the mask layer 111 according to a preset pattern.

[0037] The preset pattern indicates the pattern that the first substrate layer 10 should have, and a predetermined pattern can be formed on the mask layer 111 by exposure, development, etching, etc., so that the surface of the first substrate layer 10 can be exposed through the mask layer 111.

[0038] Referring to FIG. 3c, in step 1.21113, the exposed first substrate layer 10 is etched to form a plurality of protruding structures 112 and a plurality of recessed structures 113 on the first substrate layer 10.

[0039] Referring to FIG. 3d, in step 1.2112, the protruding structure 112 is formed On one side of the first substrate layer 10 Grow an epitaxy layer 114 , The opposite surface of the first substrate layer 10 Flat surface To be formed into An epitaxy layer 114 is grown.

[0040] Specifically, the protruding structure 112 is formed One side of the first substrate layer 10 An epitaxy layer 114 is formed on the By growing it, The opposite surface of the first substrate layer 10 Flat surface is formed in The epitaxy layer 114 Earn . Conventional techniques such as chemical vapor deposition (CVD) or hydride vapor phase epitaxy (HVPE) can be used to grow the epitaxy layer 114. Chemical vapor deposition and hydride vapor phase epitaxy are commonly used methods and will not be described again here.

[0041] In this embodiment, the material of the epitaxy layer 114 can be a III-V compound semiconductor material, specifically, a GaN-based material.

[0042] Referring to Figure 3e, in step 1.2113, the epitaxy layer 114 above each recessed structure 113 on the first substrate layer 10 is removed to expose the first substrate layer 10, and a seed crystal 115 is formed by retaining at least a portion of the epitaxy layer 114 above each protruding structure 112 on the first substrate layer 10.

[0043] Specifically, in this embodiment, the predetermined epitaxy layer 114 above each recessed structure 113 must be removed to completely expose the first substrate layer 10, and no epitaxy layer material must remain on the exposed surface of the first substrate layer 10. In addition, the predetermined epitaxy layer 114 above each protrusion structure 112 must be reserved, and the predetermined epitaxy layer 114 reserved above each protrusion structure 112 serves as a seed crystal 115.

[0044] Referring to Figure 3f, in step 1.212, a thin film layer 11 is grown on the seed crystal 115.

[0045] Specifically, a semiconductor thin film material is grown on a seed crystal 115, The surface of the thin film layer 11 located opposite the first substrate layer 10 is Flat surface to The growth of the semiconductor thin film material continues until the thin film layer 11 and the seed crystal 115 are formed. It is preferable to use the same material as the seed crystal 115. Conventional techniques such as chemical vapor deposition, vapor phase epitaxy, or molecular beam epitaxy can be used to grow a semiconductor thin film material on the seed crystal 115. Vapor phase epitaxy and molecular beam epitaxy are commonly used methods, so they will not be described again here.

[0046] It should be noted that other methods for manufacturing the thin film layer 11 can also be used in this embodiment, but the present invention does not describe them.

[0047] In step 1.3, a second substrate layer 12 is formed on the side of the thin film layer 11 remote from the first substrate layer 10.

[0048] Referring to Figure 2c, in step 1.31, a second substrate layer 12 is selected.

[0049] The material of the second substrate layer 12 can be, for example, a GaN-based material or SiC. In other embodiments, other materials can be used as the material of the second substrate layer 12, and the present invention does not describe them one by one.

[0050] The second substrate layer 12 and the thin film layer 11 may be made of: Both are GaN-based Use the materials.

[0051] The materials of the second substrate layer 12 and the thin film layer 11 are both GaN-based materials.

[0052] In step 1.32, the thin film layer 11 and the second substrate layer 12 are bonded together.

[0053] In this embodiment, by bonding the thin film layer 11 and the second substrate layer 12 together, a temporary substrate can be formed on one side of the thin film layer 11 that is away from the first substrate layer 10, and the temporary substrate can be the second substrate layer 12.

[0054] In step 1.321, the thin film layer 11 and the second substrate layer 12 are bonded together by an adhesive layer.

[0055] The adhesive layer includes a first adhesive layer and a second adhesive layer.

[0056] The step 1.321 may include, for example, steps 1.3211 to 1.3213. Referring to Figure 2d, in step 1.3211, a first adhesive layer 121 is formed on the thin film layer 11.

[0057] For example, the first adhesive layer 121 can be formed by applying a layer of adhesive material onto the thin film layer 11 by a coating method. The material of the first adhesive layer 121 can be, for example, SiO2.

[0058] Referring to FIG. 2e, in step 1.3212, a second adhesive layer 122 is formed on the second substrate layer 12.

[0059] For example, the second adhesive layer 122 can be formed by applying a layer of adhesive material onto the second substrate layer 12 by a coating method. The material of the second adhesive layer 122 can be, for example, SiO2.

[0060] Referring to Figure 2f, in step 1.3213, the thin film layer 11 and the second substrate layer 12 are bonded together by a first adhesive layer 121 and a second adhesive layer 122.

[0061] Specifically, the first adhesive layer 121 on the thin film layer 11 and the second adhesive layer 122 on the second substrate layer 12 are bonded together.

[0062] In step 1.322, the thin film layer 11 and the second substrate layer 12 are bonded together by a wafer bonding method.

[0063] Specifically, the thin film layer 11 and the second substrate layer 12 are bonded together by applying a certain pressure to the second substrate layer 12 in a certain temperature and vacuum environment, and the second substrate layer 12 can be stably attached to the thin film layer 11. When the thin film layer 11 and the second substrate layer 12 are bonded together, a plasma treatment process can be further carried out.

[0064] Referring to FIG. 2g, in step 2, the first substrate layer 10 is peeled off from the thin film layer 11.

[0065] Specifically, the first substrate layer 10 can be peeled off from the thin film layer 11 by a laser peeling method or a chemical etching method.

[0066] In this embodiment, when peeling the first substrate layer 10, the first substrate layer 10 can be peeled off from the thin film layer 11 by a laser peeling method. Specifically, a laser beam is irradiated onto one side of the first substrate layer 10 away from the thin film layer 11, thereby obtaining the thin film layer 11 and the second substrate layer 12, which are sequentially superimposed on each other.

[0067] Specifically, a laser beam having a certain power is irradiated onto one side of the first substrate layer 10 away from the thin film layer 11. In this case, the laser beam passes through a predetermined portion of the first substrate layer 10 and is irradiated onto the thin film layer 11, and the bonded portions of the first substrate layer 10 and the thin film layer 11 are separated by the energy of the laser beam. As a result, the first substrate layer 10 can be peeled off from the thin film layer 11.

[0068] In another embodiment, the first substrate layer 10 can be peeled off from the thin film layer 11 by chemical etching. Specifically, by treating the first substrate layer 10 and the thin film layer 11 with an alkaline solution or a liquid alkali in a dissolved state, a single crystal substrate can be obtained, and the thin film layer 11 and the second substrate layer 12 can be obtained, which are sequentially superimposed on each other.

[0069] Specifically, the first substrate layer 10, thin film layer 11, and second substrate layer 12, which are stacked in this order, are immersed in a chemical etching solution. Preferably, they are immersed in an alkaline solution or a liquid alkali in a dissolved state. Typically, they are immersed in KOH or NaOH. When the chemical etching solution is an alkaline solution, the concentration of the alkaline solution is 0.1% to 99.9%, preferably 40%, and the chemical etching temperature is 0°C to 100°C, preferably 80°C. When the chemical etching solution is a liquid alkali in a dissolved state, the temperature of the liquid alkali in a dissolved state is 100°C to 400°C, preferably 230°C. Because the materials of the thin film layer 11 and the second substrate layer 12 are both GaN-based materials, the GaN-based material connected to the first substrate layer 10 dissolves, causing the connection between the first substrate layer 10 and the thin film layer 11 to break and tear, allowing the thin film layer 11 to detach from the first substrate layer 10.

[0070] Referring to FIG. 2h, in step 3, the material of the thin film layer 11 is applied to the surface of the thin film layer 11 that is away from the second substrate layer 12. same A thick film layer 13 is formed by growing the material.

[0071] Specifically, after removing the first substrate layer 10, the thin film layer 11 is bonded onto the second substrate layer 12. At this time, the second substrate layer 12 is used as a temporary substrate to bond the material of the thin film layer 11 onto the thin film layer 11. same The thin layer 11 is transformed into a thick layer 13 by growing the material.

[0072] For example, a layer of the material of the thin film layer 11 is formed on the surface of the thin film layer 11 that is separated from the second substrate layer 12 by MOCVD or HVPE. same The thick film layer 13 is formed by growing the material. It should be noted that other growth methods can be adopted to manufacture the thick film layer 13, which are not specifically described in the present invention.

[0073] The size of the thick film layer 13 can be 2 inches, 4 inches, 6 inches, 8 inches, 10 inches, or 12 inches, or other sizes.

[0074] Referring to FIG. 2i, in step 4, the second substrate layer 12 is peeled away from the thick film layer 13, leaving the thick film layer 13 in place.

[0075] Specifically, the first adhesive layer 121 and the second adhesive layer 122 are removed by chemical etching, and the second substrate layer 12 is peeled off from the thick film layer 13, thereby obtaining the thick film layer 13.

[0076] After the second substrate layer 12 is peeled off from the thick film layer 13, the thick film layer 13 is planarized by chemical mechanical polishing (CMP) to obtain a flat thick film substrate.

[0077] When the diameter of the substrate is too large, it is impossible to grow a thick GaN film on the substrate using conventional methods. When a thick film is grown on a substrate using conventional methods and then peeled off, the maximum size of the substrate can reach 4 inches. When the substrate size reaches 6 inches, the yield rate of the substrate may drop significantly. This is because there is a lattice mismatch and thermal mismatch between the substrate and GaN, and the thick film can cause the substrate to bend or tear significantly. The larger the substrate size, the easier it is to tear the substrate. The self-supporting substrate fabrication method of this embodiment allows a thin film to be grown on a substrate with a large diameter, and the thin film thickness prevents tearing of the thin film and / or the substrate. This allows for the production of a thin film with a very large diameter and a self-supporting substrate with a large size.

[0078] Specifically, in the conventional method, a thick GaN film is formed on a heterogeneous substrate. However, when forming a thick GaN film on a heterogeneous substrate, the substrate may be easily bent due to lattice mismatch and thermal mismatch. The larger the size of the thick GaN film, the larger the size of the substrate. This may cause the substrate to bend more, which may have a significant impact on the yield rate of the thick GaN film. In this embodiment, a thin thin film layer is first formed on a first substrate layer. Next, a thin film layer is formed on the first substrate layer. of With a thin layer of material on top Same A second substrate layer is formed. Next, the first substrate layer is peeled off. Finally, a thick film layer is formed by growing a thin film layer, thereby forming a GaN thick film. The second substrate layer can be formed of the same material as the thin film layer or a material with a thermal expansion coefficient similar to that of the thin film layer. This avoids thermal mismatch due to dissimilar materials and prevents the thick film from bending or tearing during formation. Therefore, a large, flat, self-supporting GaN thick film can be formed, ensuring a high yield rate of the thick film.

[0079] The thick-film substrate manufactured by the method for manufacturing a self-supporting substrate of this embodiment has the following characteristics: the material of the manufactured thick-film substrate is a GaN material, the surface separated from the second substrate layer is a Ga-face, and the surface growing on the first substrate layer is a Ga-face, and this face is oriented in the crystal direction of the C-axis.

[0080] The method for manufacturing a self-supporting substrate in this embodiment makes it possible to manufacture large-sized self-supporting GaN substrates, significantly reducing the costs of research and manufacturing GaN materials and components, and gaining research and business value in the application of GaN.

[0081] In the present specification, the terms "first" and "second" are used to describe an item of the present invention, and do not express or imply the importance or quantity of the technical features of the item of the present invention. A feature followed by "first" or "second" expresses or implies that one or more features are included. Unless otherwise specified, the term "plurality" means that two or more items are included.

[0082] In the present specification, unless otherwise specified, a statement that a first feature is provided "on" or "below" a second feature can mean that the first and second features are in direct contact with each other, or that the first and second features are not in direct contact with each other but are indirectly in contact with each other via another feature. A statement that a first feature is provided "on top," "above," or "on the upper surface" of a second feature can mean that the first feature is provided directly above the second feature or at the top of a slope, or that the height of the first feature is higher than the height of the second feature. A statement that a first feature is provided "below," "below," or "on the lower surface" of a second feature can mean that the first feature is provided directly below the second feature or at the bottom of a slope, or that the height of the first feature is lower than the height of the second feature.

[0083] In the present specification, the terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" mean that a specific feature, structure, material, or characteristic of the current embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the terms are merely examples of the present invention and do not necessarily represent the same embodiment or example. Specific features, structures, materials, or characteristics described in any one embodiment or example may be combined as appropriate. Furthermore, a person skilled in the art may combine various embodiments or examples in this specification as appropriate.

[0084] Although the preferred embodiments of the present invention have been described above in detail, the above embodiments are merely illustrative of the present invention, and the present invention is not limited to the configurations of the above embodiments. Those skilled in the art may make design changes, substitutions, and improvements without departing from the spirit of the present invention, and such design changes, substitutions, and improvements are naturally included within the scope of the claims of the present invention.

Claims

1. 1. A method for manufacturing a self-supporting substrate, comprising: forming a thin film bottom portion including a first substrate layer, a thin film layer made of a GaN-based material, and a second substrate layer made of the same material as the thin film layer, which are stacked in this order; peeling the first substrate layer from the thin film layer; converting the thin film layer into a thick film layer by continuing to grow the same material as the thin film layer on a surface of the thin film layer opposite the second substrate layer; peeling the second substrate layer from the thick film layer, retaining the thick film layer; The step of forming the thin film bottom further comprises: the substep of selecting a first substrate layer; forming a thin film layer on an upper surface of the first substrate layer, the thin film layer being made of a material different from that of the first substrate layer; and bonding the second substrate layer to a side of the thin film layer opposite the first substrate layer; The sub-step of forming a thin film layer made of a material different from the material of the first substrate layer on the upper surface of the first substrate layer specifically includes: forming a plurality of seed crystals on a first substrate layer; and growing the thin film layer on the plurality of seed crystals; When forming a plurality of seed crystals on the first substrate layer, specifically: forming a plurality of protruding structures and a plurality of recessed structures on a surface of the first substrate layer by a patterning method; growing an epitaxy layer having a flat surface and made of a GaN-based material on the surface of the first substrate layer to cover the plurality of protruding structures and the plurality of recessed structures; forming the plurality of seed crystals by removing the epitaxy layer above the plurality of recessed structures in the first substrate layer to expose the first substrate layer and retaining the epitaxy layer above the plurality of protruding structures in the first substrate layer.

2. Bonding the second substrate layer to a side of the thin film layer opposite the first substrate layer includes: adhering the thin film layer and the second substrate layer together with an adhesive layer; bonding the thin film layer and the second substrate layer together by a wafer bonding method; 2. The method of claim 1, further comprising:

3. the adhesive layer includes a first adhesive layer and a second adhesive layer; Adhering the thin film layer and the second substrate layer together with an adhesive layer comprises: forming a first adhesive layer on the thin film layer; forming a second adhesive layer on the second substrate layer; bonding the thin film layer and the second substrate layer together with the first adhesive layer and the second adhesive layer; 3. The method of claim 2, further comprising:

4. 2. The method for manufacturing a self-supporting substrate according to claim 1, wherein peeling the first substrate layer from the thin film layer comprises peeling the first substrate layer from the thin film layer by a laser peeling method or a chemical etching method.

5. converting the thin film layer into a thick film layer by continuing to grow the same material as the thin film layer on a surface of the thin film layer opposite the second substrate layer, 2. The method for manufacturing a self-supporting substrate according to claim 1, wherein a thick layer is formed by continuing to grow the same material as the thin layer on the surface of the thin layer opposite the second substrate layer by MOCVD or HVPE.

6. peeling the second substrate layer from the thick film layer and retaining the thick film layer; 2. The method of claim 1, further comprising the step of peeling the second substrate layer from the thick film layer by a chemical etching method.

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