JP2014011300A - Method for manufacturing semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a semiconductor device using a support substrate with an enhanced removal easiness.SOLUTION: A method for manufacturing a semiconductor device has a support substrate forming step for forming the support substrate, a bonding step for bonding a semiconductor layer to the support substrate, and a removing step for removing the support substrate bonded to the semiconductor layer. In the support substrate forming step, a mixed powder material containing a first powder material and a second powder material, is molded into a molded product in a predetermined shape and the molded product is sintered to form the support substrate. An average particle size of the first powder material is larger than that of the second powder material.

Description

  In this specification, a technique relating to a method for manufacturing a semiconductor device using a support substrate for bonding semiconductor layers is disclosed.

  In recent years, a bonded substrate constructed by bonding a thin film single crystal wafer and a supporting substrate has been developed. For example, a silicon carbide sintered body formed by hot pressing is used for the support substrate. Moreover, as related literature, patent document 1 is mentioned, for example.

JP 2012-4232 A

  When manufacturing a device using a bonded substrate, it is necessary to reduce the substrate thickness to, for example, 50 μm or less depending on the purpose of forming the lower electrode, the purpose of reducing the resistance component of the substrate, the purpose of improving heat dissipation, and the like. There is a case. Therefore, the support substrate used for the bonding structure is required to be easily thinned and easily removed.

  In this specification, a method for manufacturing a semiconductor device is disclosed. The method for manufacturing a semiconductor device includes a support substrate manufacturing process for manufacturing a support substrate, a bonding process for bonding a semiconductor layer to the support substrate, a removal process for removing the support substrate bonded to the semiconductor layer, It has. In the support substrate manufacturing step, a mixed powder material including a first powder material and a second powder material is formed into a molded body having a predetermined shape, and the molded body is baked to produce the support substrate. The average particle size of the first powder material is larger than the average particle size of the second powder material.

  In the above method, the support substrate has a structure in which each particle of the second powder material having a small average particle diameter enters between each particle of the first powder material having a large average particle diameter. Thereby, each particle of the second powder material serves to bind each particle of the first powder material, so that the strength of the support substrate can be increased. Further, by including the first powder material having a large average particle diameter, it is possible to increase the volume that can be removed by dropping one particle, and thus the removal rate of the support substrate can be increased.

  According to the technique disclosed in this specification, it is possible to provide a method for manufacturing a semiconductor device using a support substrate with improved ease of removal.

It is a perspective view of a bonded substrate. It is a schematic diagram of the grinding | polishing using CMP method. It is the elements on larger scale of a support substrate. It is the elements on larger scale of the grinding | polishing surface of a support substrate. It is a perspective view of a bonded substrate.

  Hereinafter, some technical features of the embodiments disclosed in this specification will be described. The items described below have technical usefulness independently.

(Characteristic 1) In the method of manufacturing a semiconductor device, the removing step may include a step of polishing the support substrate using a polishing liquid. The polishing liquid may have a composition for etching the second powder material. Since each particle of the second powder material has a larger specific surface area (surface area per unit mass) than each particle of the first powder material, it has a characteristic that it is more easily etched than each particle of the first powder material. Thereby, each particle | grain of the 2nd powder material which has the function which connects each particle | grain of 1st powder material can be removed by an etching. Therefore, since the strength of the polishing surface of the support substrate can be reduced, the polishing rate of the support substrate can be increased.

(Characteristic 2) In the method of manufacturing a semiconductor device, the removing step may include a step of polishing the support substrate using a polishing liquid. The hardness of the abrasive particles contained in the polishing liquid may be harder than the second powder material and softer than the first powder material. Each particle of the second powder material that serves to bind the particles of the first powder material can be selectively removed by the abrasive particles. Thereby, since the intensity | strength of the grinding | polishing surface of a support substrate can be reduced, the polishing rate of a support substrate can be raised. In addition, since the hardness of the abrasive particles can be made softer than that of the first powder material, the generation of scratches on the polishing surface of the support substrate can be suppressed.

(Feature 3) In the method of manufacturing a semiconductor device, the removing step may include a step of annealing the support substrate on which the semiconductor layer is bonded at a predetermined temperature equal to or higher than the melting point of the second powder material. Good. By annealing the support substrate at a predetermined temperature, each particle of the second powder material that serves to bind the particles of the first powder material can be selectively removed. Thereby, since the intensity | strength of a support substrate can be reduced, the removal rate of a support substrate can be raised.

(Feature 4) In the semiconductor device manufacturing method described above, one of the first powder material and the second powder material has a higher coefficient of thermal expansion than the coefficient of thermal expansion of the semiconductor layer. The coefficient of thermal expansion may be lower than the coefficient of thermal expansion of the semiconductor layer. The mixing ratio of the first powder material and the second powder material may be a ratio at which the thermal expansion coefficient of the semiconductor layer and the thermal expansion coefficient of the support substrate are substantially the same. When the difference in coefficient of thermal expansion between the semiconductor layer and the support substrate becomes large, peeling or cracking may occur when a high-temperature process is applied to the bonded substrate. In the substrate manufacturing method, the thermal expansion coefficient of the support substrate is adjusted by adjusting the mixing ratio of the first powder material and the second powder material, and the thermal expansion coefficient of the semiconductor layer and the thermal expansion coefficient of the support substrate are Can be controlled to be substantially the same. Thereby, the situation which peeling and a crack generate | occur | produce in a bonded substrate can be prevented.

(Feature 5) The above-described method for manufacturing a semiconductor device includes a specific layer forming step of forming a specific layer having a narrower band gap than the support substrate on the surface of the support substrate formed of a crystal material that transmits laser light. A bonding step of bonding the semiconductor layer to the surface of the specific layer; and an irradiation step of irradiating the inside of the support substrate with laser light from the surface side of the support substrate. The wavelength of the laser beam used in the irradiation step is longer than the upper limit of the absorption wavelength determined by the band gap of the support substrate and shorter than the upper limit of the absorption wavelength determined by the band gap of the specific layer. In the above method, the laser beam irradiated inside the support substrate can be transmitted through the support substrate and absorbed by the specific layer. That is, the specific layer can function as a laser light condensing layer. Therefore, by generating thermal stress in the specific layer and generating a crack, the support substrate can be separated from the semiconductor layer with the specific layer as a boundary. Therefore, it becomes possible to improve the ease of removal of the support substrate.

(Characteristic 6) In the semiconductor device manufacturing method, in the specific layer forming step, a predetermined element that narrows a band gap of the support substrate may be implanted into a surface of the support substrate. Thereby, the surface layer of the support substrate can be modified to a specific layer. Therefore, it is not necessary to newly grow or deposit the specific layer, so that the process for forming the specific layer can be reduced. In addition, the specific layer can be created while maintaining the flatness of the surface of the support substrate.

(Feature 7) In the semiconductor device manufacturing method, in the specific layer forming step, a layer formed of a material having a narrower band gap than the support substrate may be deposited or grown on the surface of the support substrate. . Thereby, a specific layer can be formed on the surface of the support substrate.

(Feature 8) In the semiconductor device manufacturing method, the support substrate may be a sapphire substrate cut out from a sapphire crystal. The plane orientation of the sapphire substrate to be cut out may be determined according to the coefficient of thermal expansion of the semiconductor layer. Thereby, by adjusting the surface orientation of the sapphire substrate, the thermal expansion coefficient of the sapphire substrate is adjusted, and the thermal expansion coefficient of the semiconductor layer and the thermal expansion coefficient of the sapphire substrate can be controlled to be substantially the same. it can. Therefore, it is possible to prevent a situation where peeling or cracking occurs in the bonded substrate.

<Configuration of bonded substrate>
FIG. 1 is a perspective view of a bonded substrate 10 according to the first embodiment. The bonded substrate 10 is formed in a substantially disk shape. The bonded substrate 10 includes a support substrate 11 disposed on the lower side and a semiconductor layer 12 bonded to the upper surface of the support substrate 11. The semiconductor layer 12 may be formed of, for example, a single crystal of a compound semiconductor (eg, 6H—SiC, 4H—SiC, GaN, AlN). For example, it may be formed of a single crystal of a single element semiconductor (eg, Si, C). The support substrate 11 is a sintered body of a ceramic composite material in which two or more kinds of ceramic material powders are mixed. The ceramic material to be used may be various materials, for example, materials such as SiC, Si, AlN, Al ₂ O ₃ , GaN, SiN, SiO ₂ and TaO.

  The semiconductor layer 12 and the support substrate 11 are produced separately. Then, the bonded substrate 10 is bonded to the support substrate 11 by bonding the semiconductor layer 12 to the support substrate 11 using a bonding method that does not use an adhesive such as room temperature bonding, plasma bonding, or hydroxyl group bonding, or a bonding method that uses an adhesive. It is formed. The bonding surface of the support substrate 11 may be flattened by polishing or the like and bonded to the semiconductor layer 12 without using an adhesive. The thickness T1 of the support substrate 11 may be determined so as to obtain mechanical strength that can withstand post-processing. The thickness T1 may be in the range of 50 μm to 1000 μm, for example. The thickness T2 of the semiconductor layer 12 may be in the range of 0.1 μm to 50 μm, for example. The diameters of the support substrate 11 and the semiconductor layer 12 may be in the range of 50 mm to 300 mm. The arithmetic mean roughness Ra of the bonding surface of the support substrate 11 may be 0.3 nm or less when using a bonding method that does not use an adhesive such as room temperature bonding. In addition, when a bonding technique using an adhesive such as Au is used, the adhesive deformed at the time of pressurization fills the gaps in the bonding surface, so that the arithmetic average roughness Ra of the bonding surface of the support substrate 11 is the adhesive. It may be larger than the case of using a joining method that does not use.

<Method for Manufacturing Semiconductor Device>
The method for manufacturing a semiconductor device according to the first embodiment includes a support substrate manufacturing process, a bonding process, and a removing process. The support substrate manufacturing process is a process for manufacturing the support substrate 11. The bonding step is a step of bonding the semiconductor layer 12 to the support substrate 11. The removing step is a step of removing the support substrate 11 bonded to the semiconductor layer 12. The removing step may be performed after various devices are formed on the bonded substrate 10.

<Support substrate manufacturing process>
A support substrate manufacturing process will be described. In the explanation example of Example 1, the case where the semiconductor layer 12 is a single crystal of GaN will be described. The case where the support substrate 11 is formed of a mixed powder material containing SiC powder and Si powder will be described. As the first step, SiC powder and Si powder are prepared. The average particle diameter of SiC powder is made larger than the average particle diameter of Si powder.

As a second step, SiC powder and Si powder are mixed. The thermal expansion coefficient of SiC is about 6.6 × 10 ⁻⁶ / K. The thermal expansion coefficient of Si is about 2.6 × 10 ⁻⁶ / K. The thermal expansion coefficient of GaN forming the semiconductor layer 12 is about 5.5 × 10 ⁻⁶ / K. That is, the thermal expansion coefficient of the semiconductor layer 12 is lower than that of SiC powder and higher than that of Si powder. Therefore, the thermal expansion coefficient of the support substrate 11 can be adjusted to be equal to the thermal expansion coefficient of the semiconductor layer 12 by adjusting the mixing ratio of the SiC powder and the Si powder. A specific mixing ratio of SiC powder and Si powder may be obtained by experiment.

  Moreover, the material contained in mixed powder material is not restricted to SiC powder and Si powder. By adding an element that becomes a dopant source (for example, phosphorus), the specific resistance of the support substrate 11 can be reduced. It is also possible to improve the sinterability of the support substrate 11 by adding an element (boron, magnesium, aluminum carbide) that becomes a sintering aid.

  As a 3rd step, the molded object of the support substrate 11 is produced by performing CIP (cold isostatic pressing) using the produced mixed powder material. And the produced molded object is baked in nitrogen atmosphere. A discharge plasma sintering apparatus or a hot press apparatus may be used for firing the compact. Thereby, the support substrate 11 which is a sintered body of the ceramic composite material is completed.

<Lamination process>
A bonding process will be described. The back surface of the GaN single crystal semiconductor layer 12 and the bonding surface of the support substrate 11 are bonded together in the atmosphere. The pressure at the time of bonding may be in a range up to 50 MPa. Thereby, the bonded substrate 10 is completed. The bonded substrate 10 has a thickness and strength for handling with a normal semiconductor device. Therefore, various known semiconductor processes such as photolithography and etching can be performed on the bonded substrate 10, and various devices can be formed on the surface of the semiconductor layer 12.

<Removal process>
A process of removing the support substrate 11 will be described. In the removing step, the bonded substrate 10 is thinned to a predetermined thickness by polishing the back surface of the bonded substrate 10 (that is, the surface opposite to the bonding surface of the support substrate 11). In the first embodiment, a case where polishing is performed by a CMP (Chemical Mechanical Polishing) method will be described.

  FIG. 2 shows a schematic diagram of polishing using the CMP method. The bonded substrate 10 is held by the carrier 20 with the support substrate 11 being the lower surface. The polishing surface of the support substrate 11 is pressed against the platen 22 on which the polishing pad 21 is pasted. Polishing is performed by rotating the carrier 20 and the platen 22 while supplying the polishing liquid 23 containing various chemical components and abrasive particles onto the polishing pad 21.

The polishing liquid 23 contains a chemical component that chemically etches Si particles at a higher rate than the SiC particles contained in the support substrate 11. Examples of chemical components include hydrofluoric acid, sulfuric acid, oxalic acid, and aqua regia. The abrasive particles contained in the polishing liquid are preferably made of a material having a hardness higher than that of the Si powder and lower than that of the SiC powder. For example, alumina (Al ₂ O ₃ ) (Knoop hardness = 1700-2500 kgf / mm ² ) has a higher hardness than Si powder (Knoop hardness = 1000 kgf / mm ² or less), and SiC powder (Knoop hardness = 2500-3200 kgf / mm ² ).

<Effect of Example 1>
The average particle size of the SiC powder is larger than the average particle size of the Si powder. Thereby, as shown in the partial enlarged view of the support substrate 11 in FIG. 3, it is possible to form a structure in which Si particles 2 having a small average particle diameter enter between SiC particles 1 having a large average particle diameter. Thereby, since each particle | grain of Si particle | grain 2 functions to link each particle | grain of SiC particle | grain 1, the intensity | strength of the support substrate 11 can be made high. In addition, by including SiC particles 1 having a large average particle diameter, the volume that can be removed by dropping one particle can be increased, so that the polishing rate of support substrate 11 can be increased. Therefore, it is possible to increase both the polishing rate of the support substrate 11 and ensure the strength of the support substrate 11.

  FIG. 4 shows a partially enlarged view of the polished surface of the support substrate 11 polished by the CMP method. The etching rate by the polishing liquid 23 is higher for the Si particles 2 than for the SiC particles 1. Each particle of the Si particles 2 has a specific surface area (surface area per unit mass) larger than that of each particle of the SiC particles 1, and therefore has a characteristic that it is more easily etched by the polishing liquid 23 than each particle of the SiC particles 1. Yes. Therefore, as shown in FIG. 4, each of the Si particles 2 functioning to bind each particle of the SiC particles 1 in the vicinity of the surface layer portion of the polishing surface of the support substrate 11 (ie, in the vicinity of the contact portion with the polishing pad 21). The particles can be removed by chemical etching with the polishing liquid 23. Thereby, the SiC particles 1 can be easily removed from the polishing surface of the support substrate 11, so that the strength of the polishing surface of the support substrate 11 can be reduced and the polishing rate of the support substrate 11 can be increased.

  The hardness of the abrasive particles 3 contained in the polishing liquid 23 is harder than the Si particles 2 and softer than the SiC particles 1. Therefore, as shown in FIG. 4, in the vicinity of the surface layer portion of the polishing surface of the support substrate 11, each particle of the Si particles 2 that serves to bind each particle of the SiC particles 1 is selectively removed by the polishing particles 3. be able to. Thereby, the polishing rate of the support substrate 11 can be increased. Further, by making the hardness of the abrasive particles 3 softer than that of the SiC particles 1, it is possible to suppress the generation of scratches on the polished surface of the support substrate 11.

  When the difference in coefficient of thermal expansion between the semiconductor layer 12 and the support substrate 11 becomes large, peeling or cracking may occur in the bonded substrate 10 when a high temperature process is applied to the bonded substrate 10. In the support substrate manufacturing process described in this specification, the thermal expansion coefficient of the semiconductor layer 12 and the support substrate are adjusted by adjusting the thermal expansion coefficient of the support substrate 11 by adjusting the mixing ratio of the SiC powder and the Si powder. The thermal expansion coefficient of 11 can be controlled to be substantially the same. Thereby, the situation which peeling and a crack generate | occur | produce in the bonded substrate 10 can be prevented.

<Configuration of bonded substrate>
FIG. 5 is a perspective view of the bonded substrate 10a according to the second embodiment. The bonded substrate 10 a includes a support substrate 11 disposed on the lower side, a specific layer 13 disposed on the upper surface of the support substrate 11, and a semiconductor layer 12 bonded to the upper surface of the specific layer 13. The material of the support substrate 11 may be any kind of material as long as it is a material that transmits laser light. For example, a sintered body of a crystal material or a ceramic powder material may be used as the material of the support substrate 11. The specific layer 13 is a layer formed of a crystal material having a narrower band gap than the support substrate 11. The semiconductor layer 12 may be formed of a single crystal of various compound semiconductors or single element semiconductors. The thickness T11 of the support substrate 11 may be in the range of 50 μm to 1000 μm, for example. The thickness T13 of the semiconductor layer 12 may be in the range of 0.1 μm to 50 μm, for example. In Example 2, a case where the support substrate 11 is formed of sapphire crystal will be described as an example. A case where the semiconductor layer 12 is formed of 6H—SiC crystal will be described.

<Method for Manufacturing Semiconductor Device>
The method for manufacturing a semiconductor device according to the second embodiment includes a specific layer forming step, a bonding step, and an irradiation step. The specific layer forming step is a step of forming a specific layer on the surface of the support substrate 11. The bonding step is a step of bonding the semiconductor layer 12 to the support substrate 11. The irradiation step is a step of separating the support substrate 11 bonded to the semiconductor layer 12 by irradiating the inside of the support substrate 11 with laser light from the surface side of the support substrate 11.

<Specific layer formation process>
The specific layer forming step will be described. As a first step, the support substrate 11 is cut out from an ingot of sapphire crystal. The sapphire crystal has a characteristic that the coefficient of thermal expansion of the main surface changes depending on the cutting direction. Therefore, the plane orientation of the main surface of the support substrate 11 cut out in the first step may be determined so that the difference between the thermal expansion coefficient of the main surface of the support substrate 11 and the thermal expansion coefficient of the semiconductor layer 12 is small. .

  As a second step, the specific layer 13 is formed on the surface of the bonding surface of the support substrate 11. Specifically, a predetermined element is implanted into the surface of the bonding surface of the support substrate 11. The predetermined element may be any element as long as the band gap of the specific layer 13 can be narrower than the band gap of the support substrate 11. For example, elements such as nitrogen, phosphorus, boron, chromium, scandium, tin, aluminum, and hydrogen may be used. For implantation of the predetermined element, an ion implantation apparatus conventionally used in a semiconductor manufacturing process may be used. Since the predetermined element only needs to be implanted shallowly into the surface of the support substrate 11, the acceleration energy may be lower than that of normal implantation, and may be several keV, for example.

<Lamination process>
In the bonding step, the bonded substrate 10a is created by bonding the back surface of the semiconductor layer 12 and the surface of the specific layer 13 in the air. Moreover, various devices can be formed on the surface of the semiconductor layer 12 by performing various known semiconductor processes on the bonded substrate 10a. In addition, since the content of the bonding process has already been described in the first embodiment, the description thereof is omitted here.

<Irradiation process>
In the irradiation step, laser light is irradiated from the surface side of the support substrate 11 (arrow Y1 side in FIG. 5) to the inside of the support substrate. The wavelength of the laser light is longer than the upper limit of the absorption wavelength (wavelength of the optical absorption edge) determined by the band gap of the sapphire crystal forming the support substrate 11, and the upper limit of the absorption wavelength (optical absorption edge) determined by the band gap of the specific layer 13. Shorter wavelength). By using a laser beam having such a wavelength, the laser beam applied to the inside of the support substrate 11 can be transmitted through the support substrate 11 and absorbed by the specific layer 13. That is, the specific layer 13 can function as a laser light condensing layer. As a result, the specific layer 13 can be selectively heated without performing a process of condensing the laser light using a lens or the like. Therefore, a thermal stress can be generated in the specific layer 13 to generate a crack. In the irradiation process, the bonded substrate 10a is moved in a direction parallel to the specific layer 13 using a stage (not shown) or the like, so that the laser beam is scanned relative to the bonded substrate 10a. Thereby, a crack can be generated on the entire surface of the specific layer 13 by irradiating the entire surface of the specific layer 13 with laser light. Therefore, the specific layer 13 is broken starting from a crack generated on the entire surface of the specific layer 13, and the semiconductor layer 12 can be separated from the support substrate 11.

<Effect of Example 2>
The laser light applied to the inside of the support substrate 11 can be transmitted through the support substrate 11 and absorbed by the specific layer 13. Accordingly, it is possible to separate the support substrate 11 from the semiconductor layer 12 with the specific layer 13 as a boundary by generating a thermal stress in the specific layer 13 to generate a crack. Therefore, it becomes possible to improve the ease of removal of the support substrate 11.

  By implanting a predetermined element that narrows the band gap of the support substrate 11 into the surface of the support substrate 11, the surface layer of the support substrate 11 can be modified to the specific layer 13. Therefore, it is not necessary to newly grow or deposit the specific layer 13, so that it is possible to reduce the process for forming the specific layer 13. In addition, the specific layer 13 can be created while maintaining the flatness of the surface of the support substrate 11.

  By adjusting the plane orientation of the main surface of the support substrate 11 that is a sapphire crystal, the thermal expansion coefficient of the support substrate 11 is adjusted, and the thermal expansion coefficient of the semiconductor layer 12 and the thermal expansion coefficient of the support substrate 11 are substantially the same. It can control to become. Therefore, it is possible to prevent a situation in which peeling or cracking occurs in the bonded substrate 10a.

  As mentioned above, although the Example of this invention was described in detail, these are only illustrations and do not limit a claim. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

<Modification>
In the removal process of Example 1, various methods can be used as a method of removing various particles contained in the support substrate 11. For example, in the removing step, the bonded substrate 10 may be annealed at a predetermined temperature equal to or higher than the melting point of Si particles (about 1410 ° C.). Thereby, each particle | grain of the Si particle which has the function which connects each particle | grain of a SiC particle can be removed. Therefore, the polishing rate of the support substrate 11 can be increased.

  When the support substrate is a sintered body of a ceramic composite material, a large number of voids appear on the surface of the joint surface, so that the surface roughness increases. Therefore, the surface roughness may be reduced by modifying the surface of the bonding surface of the support substrate before performing the bonding step. Examples of the method for modifying the surface include a method of forming a planarization layer on the bonding surface. In addition, the planarization layer is preferably formed using a material having a high reflow property so that the void can be filled. As an example of a material having a high reflow property, BPSG (Boron Phosphorus Silicon Glass) or a metal film having a low melting point such as Al can be given. Thereby, it becomes possible to improve the adhesiveness of a support substrate and a semiconductor layer.

  In Example 2, the material used for the support substrate may be any kind of material as long as it is a material that transmits laser. For example, it is possible to use polycrystalline SiC for the support substrate. In addition, various polytypes of SiC crystals may be mixed in the polycrystalline SiC. Since polycrystalline SiC in which various polytypes are mixed can be manufactured without performing strict temperature control, the cost for manufacturing the support substrate can be reduced.

  By forming an insulating layer between the support substrate 11 and the semiconductor layer 12, a bonded substrate having a structure similar to that of a so-called SOI (Silicon on Insulator) may be formed. Whether or not the bonded substrate is formed with a structure similar to that of SOI may be determined based on the type of device manufactured in the semiconductor layer 12. For example, when a lateral device that forms elements such as transistors in the direction along the wafer surface is manufactured in the semiconductor layer 12, the bonded substrate may be formed with a structure similar to that of SOI. Further, in the case where a vertical device that forms elements in a direction perpendicular to the wafer surface is manufactured in the semiconductor layer 12, the bonded substrate may not be formed with a structure similar to that of SOI.

The sintered body is a porous body and contains many voids. Therefore, when the thermal expansion coefficients of the sintered body and the crystal body of the same material are compared, the thermal expansion coefficient of the sintered body may be lower. Even in such a case, in the support substrate manufacturing process, the material obtained by pulverizing the crystal forming the semiconductor layer and the material pulverizing the crystal having a higher thermal expansion coefficient than the crystal forming the semiconductor layer are converted into the semiconductor layer. The coefficient of thermal expansion and the coefficient of thermal expansion of the support substrate may be mixed at a ratio that is substantially the same. For example, when the semiconductor layer 12 is a single crystal of GaN (thermal expansion coefficient = about 5.5 × 10 ⁻⁶ / K), GaN powder material and SiC (thermal expansion coefficient = about 6.6 × 10 6). ^The support substrate 11 may be formed using a material obtained by mixing a powder material of ⁻⁶ / K).

  Although the case where CMP is used for the polishing process performed in the removal process has been described, the present invention is not limited to this form. For polishing, mechanical polishing, chemical polishing, or the like can be used. Mechanical polishing is a polishing method using a polishing pad carrying abrasive grains such as diamond. Chemical polishing is a method that uses a chemical that removes irregularities on the surface of a support substrate as a polishing liquid.

  The method of forming the specific layer in the specific layer forming step is not limited to the method of implanting a predetermined element on the surface of the support substrate. A method of depositing a specific layer formed of a material having a narrower band gap than the support substrate on the surface of the support substrate by a CVD method or a method of epitaxial growth may be used.

  The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

  1: SiC particles, 2: Si particles, 10 and 10a: bonded substrate, 11: support substrate, 12: semiconductor layer, 13: specific layer

Claims (9)

A method for manufacturing a semiconductor device, comprising:
A support substrate manufacturing process for manufacturing a support substrate;
A bonding step of bonding a semiconductor layer to the support substrate;
A removal step of removing the support substrate bonded to the semiconductor layer;
With
In the support substrate manufacturing step, a mixed powder material including a first powder material and a second powder material is formed into a molded body having a predetermined shape, and the molded body is baked to produce the support substrate.
The method of manufacturing a semiconductor device, wherein an average particle size of the first powder material is larger than an average particle size of the second powder material. The removing step includes a step of polishing the support substrate using a polishing liquid,
The method for manufacturing a semiconductor device according to claim 1, wherein the polishing liquid has a composition for etching the second powder material. The removing step includes a step of polishing the support substrate using a polishing liquid,
3. The method of manufacturing a semiconductor device according to claim 1, wherein the abrasive particles contained in the polishing liquid are harder than the second powder material and softer than the first powder material. 4.   4. The method according to claim 1, wherein the removing step includes a step of annealing the support substrate to which the semiconductor layer is bonded at a predetermined temperature equal to or higher than a melting point of the second powder material. A method for manufacturing the semiconductor device according to the item. Of the first powder material and the second powder material, one material has a thermal expansion coefficient higher than that of the semiconductor layer, and the other material has a thermal expansion coefficient higher than that of the semiconductor layer. Low,
The mixing ratio of the first powder material and the second powder material is a ratio at which the thermal expansion coefficient of the semiconductor layer and the thermal expansion coefficient of the support substrate are substantially the same. The method for manufacturing a semiconductor device according to any one of the above. A method for manufacturing a semiconductor device, comprising:
A specific layer forming step of forming a specific layer having a narrower band gap than the support substrate on the surface of the support substrate formed of a crystal material that transmits laser light;
A bonding step of bonding a semiconductor layer to the surface of the specific layer;
An irradiation step of irradiating the inside of the support substrate with laser light from the surface side of the support substrate;
With
The wavelength of the laser beam used in the irradiation step is longer than the upper limit of the absorption wavelength determined by the band gap of the support substrate, and shorter than the upper limit of the absorption wavelength determined by the band gap of the specific layer. A method for manufacturing a semiconductor device. In the specific layer forming step,
The method for manufacturing a semiconductor device according to claim 6, wherein a predetermined element that narrows a band gap of the support substrate is implanted into a surface of the support substrate. In the specific layer forming step,
The method for manufacturing a semiconductor device according to claim 6, wherein a layer formed of a material having a narrower band gap than the support substrate is deposited or grown on the surface of the support substrate. The support substrate is a sapphire substrate cut out from a sapphire crystal,
The method of manufacturing a semiconductor device according to claim 6, wherein a plane orientation of the cut-out sapphire substrate is determined according to a coefficient of thermal expansion of the semiconductor layer.

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