Composite substrate for SiC single crystal transfer, method for producing composite substrate for SiC single crystal transfer, and method for producing SiC bonded substrate

Abstract

The present invention provides a composite substrate for SiC single crystal transfer, a method for manufacturing a composite substrate for SiC single crystal transfer, and a method for manufacturing a SiC bonded substrate, which can improve warpage of a SiC single crystal substrate repeatedly used in a process for manufacturing a SiC bonded substrate, thereby suppressing a transfer error of the SiC single crystal substrate and a defect that the SiC single crystal substrate cannot be held on a processing table. In addition, the SiC single crystal substrate can be held on a processing table by an electrostatic chuck through a surface activation step and a bonding step, and the occurrence of bonding disqualification can be suppressed. A composite substrate for SiC single crystal transfer is provided with a SiC single crystal substrate and a first SiC polycrystalline substrate having a volume resistivity of 10 [Omega] cm or less, and one surface of the SiC single crystal substrate is directly bonded to one surface of the first SiC polycrystalline substrate via a covalent bond.

Description

Technical Field

[0001] The present invention relates to the technical field of a SiC bonded substrate composed of a SiC single crystal thin film produced by separating a SiC single crystal thin film from the surface of a SiC single crystal substrate and a SiC polycrystalline substrate for bonding a SiC single crystal substrate used for semiconductor devices, etc., and in particular to a composite substrate for SiC single crystal transfer, a method for manufacturing a composite substrate for SiC single crystal transfer, and a method for manufacturing a SiC bonded substrate. Background Art

[0002] Silicon carbide (hereinafter sometimes referred to as "SiC") has a band gap about three times larger than that of silicon (hereinafter sometimes referred to as "Si") (4H-SiC is about 3.8 eV, 6H-SiC is about 3.1 eV, and the corresponding Si is about 1.1 eV) and a high thermal conductivity (SiC is about 5 W / cm·K, and the corresponding Si is about 1.5 W / cm·K). Therefore, single crystal SiC has begun to be used as a substrate material for power devices in recent years.

[0003] Generally, a SiC single crystal substrate is produced by a vapor phase method called a sublimation recrystallization method (modified Rayleigh method) (see, for example, Non-Patent Document 1), and processed into a desired diameter and thickness.

[0004] The modified Rayleigh process is a manufacturing method in which a solid raw material of SiC (usually a powder) is heated and sublimated at a high temperature (above 2,400°C). The sublimated silicon atoms and carbon atoms are transported as 2,400°C vapor by diffusion in an inert gas atmosphere, become supersaturated on a seed crystal set to a lower temperature than the raw material, and recrystallize, thereby cultivating a bulk single crystal.

[0005] However, this method has a very high process temperature of more than 2,400°C, so it is very difficult to control the temperature of crystal growth, control convection, and control crystal defects. Therefore, in the SiC single crystal substrate produced by this method, there are many crystal defects called micropipes and other crystal defects (stacking defects, etc.), making it difficult to produce high-quality single crystal substrates that can withstand electronic device applications with high yield.

[0006] In order to manufacture high-quality single crystal substrates, various improvements are being made. For example, SiC single crystal substrates can be manufactured using the CVD method. However, since the SiC single crystal manufactured by this method is a high-quality SiC single crystal with few crystal defects that can be used for electronic devices, it is expensive, and the equipment using the expensive SiC single crystal also becomes expensive, thus becoming an obstacle to the popularization of SiC single crystal substrates.

[0007] Therefore, the following technology is provided: by using a high-quality SiC single crystal only in the device forming layer portion and fixing it to a supporting substrate (a material having strength, heat resistance, and cleanliness that can withstand the device manufacturing process: for example, SiC polycrystal) by a bonding method that is not accompanied by the formation of an oxide film in the bonding interface, a SiC bonding substrate with both low cost (supporting substrate portion) and high quality (SiC portion) is manufactured (for example, refer to Patent Document 1).

[0008] The manufacturing process of the SiC bonded substrate is described in detail. First, in the planarization process, the surface of the SiC polycrystalline supporting substrate is planarized by mechanical grinding such as grinding, lapping or polishing. In addition, in the planarization process, the surface of the SiC single crystal substrate is also planarized. Since there are no grains with different crystal orientations in the substrate surface of the SiC single crystal substrate, the surface of the substrate can be further planarized by chemical mechanical polishing after the above-mentioned mechanical polishing. Next, in the ion implantation process, hydrogen ions are implanted from the planarized surface of the SiC single crystal substrate. Thus, a hydrogen ion implantation layer is formed at a predetermined depth from the surface of the SiC single crystal substrate. It is separated from this part by the separation technology based on ablation of hydrogen atoms described later. The depth of the hydrogen ion implantation layer can be controlled by the energy of the hydrogen ions implanted, and is usually in the range of 0.5 to 1.0 μm.

[0009] Furthermore, a surface activation method is used on the surfaces of the flattened polycrystalline SiC and SiC single crystal substrates to bond the surfaces. Then, the polycrystalline SiC and SiC single crystal substrates in a bonded state are heated. As a result, the SiC single crystal substrate is broken and separated by the above-mentioned hydrogen ion implantation layer. A high-quality SiC single crystal film with a thickness of 0.5 to 1.0 μm is transferred and bonded to the surface of the SiC polycrystalline substrate as a supporting substrate to obtain a SiC bonded substrate.

[0010] Then, the SiC single crystal substrate thinned by about 1 μm due to separation at the hydrogen ion implantation layer is repeatedly supplied to produce a bonded substrate by flattening the substrate surface on the re-bonded side while having a sufficient thickness for transfer.

[0011] When a SiC bonded substrate is made using the manufacturing method described in Patent Document 1, the SiC single crystal substrate used repeatedly gradually becomes thinner each time it is bonded and separated. If the thickness of the SiC single crystal substrate becomes thinner, the warping of the SiC single crystal substrate becomes larger. In particular, due to the stress inside the substrate generated by the formation of a hydrogen ion implantation layer in the above-mentioned ion implantation process, the warping of the SiC single crystal substrate after hydrogen ion implantation becomes significantly larger, resulting in the undesirable conditions of transport errors of the SiC single crystal substrate and the inability to keep the SiC single crystal substrate on the processing table. In addition, since the inside of the device becomes a vacuum state in the surface activation process and the bonding process, the SiC single crystal substrate cannot be vacuum adsorbed and kept on the processing table, which easily leads to bonding failures such as the inability to uniformly bond the above-mentioned SiC polycrystalline substrate and the SiC single crystal substrate.

[0012] Prior art literature

[0013] Patent Literature

[0014] Patent Document 1: Japanese Patent Application Publication No. 2015-015401

[0015] Non-patent literature

[0016] Non-patent document 1: Yu.M.Tairov and VFTsvetkov: J. of Cryst. Growth 43 (1978) 209 Summary of the invention

[0017] Problems to be solved by the invention

[0018] Therefore, the object of the present invention is to provide the following composite substrate for SiC single crystal transfer, a method for manufacturing a composite substrate for SiC single crystal transfer, and a method for manufacturing a SiC bonded substrate: by improving the warping of SiC single crystal substrates repeatedly used in the manufacturing process of SiC bonded substrates, the undesirable conditions of transporting errors of SiC single crystal substrates and inability to hold SiC single crystal substrates on a processing table are suppressed, and the SiC single crystal substrate can be held on the processing table by an electrostatic chuck through a surface activation process and a bonding process, and the occurrence of unqualified bonding can be suppressed.

[0019] Means used to solve problems

[0020] In order to solve the above-mentioned problems, the composite substrate for SiC single crystal transfer of the present invention comprises a SiC single crystal substrate and a first SiC polycrystalline substrate having a volume resistivity of 10 Ω·cm or less, wherein one surface of the SiC single crystal substrate is directly bonded to one surface of the first SiC polycrystalline substrate by a covalent bond.

[0021] The first SiC polycrystalline substrate may be in a wafer shape, and a maximum value of a circumferential contour line of the first SiC polycrystalline substrate may be the same as a circumferential contour line of a bonding surface between the SiC single crystal substrate and the first SiC polycrystalline substrate.

[0022] In addition, in order to solve the above-mentioned problems, the manufacturing method of the composite substrate for SiC single crystal transfer of the present invention includes: a first activation step, in which a high-speed atomic beam is irradiated to the first bonding object surface of the SiC single crystal substrate and the bonding object surface of the first SiC polycrystalline substrate to activate these bonding object surfaces; and a first room temperature bonding step, in which, after the first activation step, the first bonding object surface of the SiC single crystal substrate and the bonding object surface of the first SiC polycrystalline substrate are directly bonded at room temperature by covalent bonds.

[0023] It may also include a side grinding process, in which, after the first room temperature bonding process, the side of the first SiC polycrystalline substrate is ground to remove the recessed portion formed by the side of the SiC single crystal substrate, the side of the first SiC polycrystalline substrate, and the circumferential contour of the bonding surface between the SiC single crystal substrate and the first SiC polycrystalline substrate.

[0024] In addition, in order to solve the above-mentioned problems, the manufacturing method of the SiC bonding substrate of the present invention comprises: a hydrogen ion implantation layer forming step, in which hydrogen ions are implanted into the second bonding target surface of the SiC single crystal substrate in the SiC single crystal transfer composite substrate of the present invention to form a hydrogen ion implantation layer inside the SiC single crystal substrate; a second activation step, in which a high-speed atomic beam is irradiated to the second bonding target surface of the SiC single crystal substrate and the bonding target surface of the second SiC polycrystalline substrate to activate these bonding target surfaces; a second room temperature bonding step, in which a high-speed atomic beam is irradiated to the second bonding target surface of the SiC single crystal substrate and the bonding target surface of the second SiC polycrystalline substrate to activate these bonding target surfaces; and a second room temperature bonding step. In the present invention, after the second activation step, the second joining object surface of the SiC single crystal substrate and the joining object surface of the second SiC polycrystalline substrate are joined at room temperature in a manner that the second joining object surface is directly joined by covalent bonds; and a peeling step, in which, after the second room temperature bonding step, the SiC single crystal substrate is peeled off along the hydrogen ion implantation layer, and the SiC single crystal thin film is transferred to the second SiC polycrystalline substrate, the SiC single crystal transfer composite substrate and the second SiC polycrystalline substrate are held by an electrostatic chuck, and the second SiC polycrystalline substrate is provided with the SiC single crystal thin film.

[0025] The manufacturing method of the SiC bonding substrate of the present invention is a method for repeatedly using the SiC single crystal transfer composite substrate after the stripping process to manufacture a plurality of the SiC bonding substrates. The hydrogen ion implantation layer forming process, the second activation process, the second room temperature bonding process, and the stripping process may be repeatedly performed until the thickness of the SiC single crystal substrate of the SiC single crystal transfer composite substrate becomes less than 140 μm.

[0026] Effects of the Invention

[0027] According to the present invention, the following composite substrate for SiC single crystal transfer, a method for manufacturing a composite substrate for SiC single crystal transfer, and a method for manufacturing a SiC bonded substrate can be provided: by improving the warping of SiC single crystal substrates repeatedly used in the manufacturing process of SiC bonded substrates, the undesirable conditions of SiC single crystal substrate transportation errors and inability to hold the SiC single crystal substrate on a processing table can be suppressed, and the SiC single crystal substrate can be held on the processing table by an electrostatic chuck through a surface activation process and a bonding process, and the occurrence of bonding failures can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a flowchart showing an example of a method for manufacturing a SiC single crystal transfer composite substrate and a method for manufacturing a SiC bonded substrate according to the present invention.

[0029] Figure 2 This is a diagram showing an example of the first activation step (S1) in the present invention.

[0030] Figure 3 It is a diagram showing an example of the first room temperature bonding step (S2) in the present invention.

[0031] Figure 4 It is a diagram showing an example of the side grinding step ( S3 ) in the present invention and a schematic side view of the composite substrate for SiC single crystal transfer of the present invention.

[0032] Figure 5 It is a diagram showing an example of the hydrogen ion implantation layer forming step (S4) in the present invention.

[0033] Figure 6 This is a diagram showing an example of the second activation step (S5) in the present invention.

[0034] Figure 7 It is a diagram showing an example of the second room temperature bonding step (S6) in the present invention.

[0035] Figure 8 This is a diagram showing an example of the peeling step (S7) in the present invention.

[0036] Fig. 9 It is a figure which shows an example of the 2nd joining object surface grinding|polishing process (S8) in this invention. DETAILED DESCRIPTION

[0037] Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings.

[0038] [Composite substrate for SiC single crystal transfer]

[0039] The composite substrate for SiC single crystal transfer of the present invention is a substrate that can be used for production of a SiC bonding substrate and is a substrate that becomes an embryonic body of a SiC single crystal thin film transferred to a SiC polycrystalline substrate. Figure 4 Side views of SiC single crystal transfer composite substrates 100 to 103 according to the present invention are shown.

[0040] The SiC single crystal transfer composite substrate 100 includes a SiC single crystal substrate 200 and a first SiC polycrystalline substrate 300 , wherein a single surface 201 of the SiC single crystal substrate 200 and a single surface 301 of the first SiC polycrystalline substrate 300 are directly bonded entirely to each other by covalent bonds.

[0041] <SiC Single Crystal Substrate 200>

[0042] As the SiC single crystal substrate 200, for example, a 4H-SiC single crystal substrate produced by a sublimation method can be used. The shape of the SiC single crystal substrate 200 is, for example, a roughly disk-shaped substrate having an orientation flat surface, and a substrate having a diameter of 4 to 8 inches can be used. In addition, the shape is not limited to a disk-shaped (wafer-shaped) shape, and can also be a polygonal shape.

[0043] In addition, if the thickness of the SiC single crystal substrate 200 is reduced, the warping of the SiC single crystal substrate 200 becomes larger, and as a result, there are cases where the composite substrate 100 for SiC single crystal transfer cannot be transported due to the warping of the composite substrate 100, the composite substrate 100 for SiC single crystal transfer cannot be held on the processing table, or the composite substrate 100 for SiC single crystal transfer cannot be clamped. Therefore, it is preferred to set the overall thickness of the composite substrate 100 for SiC single crystal transfer to be 300 μm or more, which allows for warping. By setting the thickness to 300 μm or more, the composite substrate 100 for SiC single crystal transfer can be transported and held on the processing table. In addition, the initial thickness of the SiC single crystal substrate 200 is generally 300 μm to 600 μm.

[0044] Furthermore, the SiC single crystal substrate 200 is preferably one that has been subjected to chamfering of side corners, double-side polishing, grinding, cleaning, etc., to remove a processed layer or undulations on the surface of the SiC single crystal substrate 200 before being bonded to the first SiC polycrystalline substrate 300 .

[0045] <First SiC Polycrystalline Substrate 300>

[0046] The first SiC polycrystalline substrate 300 is a substrate that can reinforce the SiC single crystal substrate 200 by directly bonding to the SiC single crystal substrate 200 through a covalent bond. By reinforcing the SiC single crystal substrate 200, for example, even if the SiC single crystal substrate 200 is repeatedly used and the hydrogen ion implantation layer is peeled off and the thickness becomes thinner, the warping of the SiC single crystal substrate 200 in the hydrogen ion implantation layer forming step described later can be suppressed, and the SiC single crystal substrate 200 can be held, transported, etc. by suppressing the warping.

[0047] Considering the thermal expansion difference with the SiC single crystal substrate 200, heat resistance, high rigidity, durability for repeated use, etc., as the first SiC polycrystalline substrate 300, for example, a 3C-SiC polycrystalline substrate obtained by forming a SiC polycrystalline film by chemical vapor deposition can be used. The shape of the first SiC polycrystalline substrate 300 can be almost the same as that of the SiC single crystal substrate 200, for example, a roughly disk-shaped substrate with an orientation plane, and a substrate with a diameter of 4 to 8 inches can be used. In addition, the shape is not limited to a disk-shaped, and can also be a polygonal shape.

[0048] In addition, if the thickness of the first SiC polycrystalline substrate 300 is reduced, the reinforcing effect of alleviating the warpage of the SiC single crystal substrate 200 is weakened, and as a result, there are cases where the composite substrate 100 for SiC single crystal transfer cannot be transported due to the warpage of the composite substrate 100, the composite substrate 100 for SiC single crystal transfer cannot be held on the processing table, or the composite substrate 100 for SiC single crystal transfer cannot be clamped. Therefore, by setting the overall thickness of the composite substrate 100 for SiC single crystal transfer to 300 μm or more, which allows warpage, the composite substrate 100 for SiC single crystal transfer can be transported and held on the processing table. The thickness of the first SiC polycrystalline substrate 300 is 300 μm or more, preferably 350 μm or more, so that the holding and transport of the composite substrate 100 for SiC single crystal transfer becomes easier. In addition, the upper limit of the thickness of the first SiC polycrystalline substrate 300 does not affect the solution of the problem of the present invention and is not particularly limited, but is generally 500 μm.

[0049] The volume resistivity of the first SiC polycrystalline substrate 300 is less than 10Ω·cm. The first SiC polycrystalline substrate 300 is bonded to the SiC single crystal substrate 200 as an auxiliary substrate, and there is a situation in which bonding, peeling, grinding, washing, etc. are repeatedly performed during the manufacturing process of the SiC bonded substrate, and the bonding of the SiC bonded substrate is repeatedly supplied. Therefore, if the insulation of the first SiC polycrystalline substrate 300 is high, the grinding shavings, grinding powder, etc. generated during the grinding of the SiC single crystal transfer composite substrate 100 adhere to the first SiC polycrystalline substrate 300 and are brought into the second room temperature bonding process described later, which is likely to cause the bonding failure of the SiC single crystal substrate 200 and the second SiC polycrystalline substrate 700. By setting the volume resistivity of the first SiC polycrystalline substrate 300 to be less than 10Ω·cm, it is possible to suppress bonding failures caused by grinding shavings, grinding powder, etc.

[0050] In addition, in the second activation process and the room temperature bonding process, since the device becomes a vacuum state, the substrate of the processing object cannot be held on the processing table by the vacuum adsorption method, and needs to be held by a method other than the vacuum adsorption method. In the present invention, an electrostatic chuck method is used. Since the electrostatic chuck applies a potential difference between the dielectric film and the substrate, the substrate is held by the electrostatic force of the charge charged between the dielectric film and the wafer. Therefore, if the resistance of the substrate is high, the discharge time constant of the charge becomes large, resulting in the problem that the substrate cannot be easily peeled off. This becomes a reason for the reduction of the manufacturing processing capacity of the device in the mass production process of the substrate. Therefore, in order to use the electrostatic chuck method, the substrate to be held needs to be conductive. In the case of the composite substrate 100 for SiC single crystal transfer, since the electrostatic chuck contacts the first SiC polycrystalline substrate 300, the first SiC polycrystalline substrate 300 with conductivity is used. That is, the volume resistivity of the first SiC polycrystalline substrate 300 is set to be less than 10Ω·cm. Thus, the first SiC polycrystalline substrate 300 can be easily desorbed from the electrostatic chuck without the trouble of applying a conductive material to the substrate or improving the internal electrode structure of the electrostatic chuck. In addition, since a mechanical chuck method is not required, the mechanical chuck, which is a dust source, can be removed from the method for manufacturing the SiC bonded substrate.

[0051] In addition, the lower limit of the volume resistivity of the first SiC polycrystalline substrate 300 does not affect the solution of the problem of the present invention, and there is no special limitation, and the standard is 1Ω·cm. In addition, the volume resistivity of the first SiC polycrystalline substrate 300 varies according to the temperature of the substrate during measurement, and in this specification, the volume resistivity is a value when the temperature of the first SiC polycrystalline substrate 300 is 25°C.

[0052] Then, the first SiC polycrystalline substrate 300 is preferably a material that has been subjected to chamfering of side corners, double-side polishing, grinding, cleaning, etc., to remove a processed layer and undulations on the surface of the first SiC polycrystalline substrate 300 before being bonded to the SiC single crystal substrate 200 .

[0053] The SiC single crystal substrate 200 and the first SiC polycrystalline substrate 300 are generally chamfered on their side surfaces before bonding. When the SiC single crystal transfer composite substrate 100 is viewed from the side, Figure 4 As shown in (a) in FIG. 1 , the outline 110 of the bonding surface is recessed, and the diameter of the outline 110 of the composite substrate 100 for SiC single crystal transfer is smaller than the diameter of the outline line 350 of the circumference described later at the side of the composite substrate 100 for SiC single crystal transfer. The composite substrate 100 for SiC single crystal transfer may be repeatedly bonded, peeled, polished, cleaned, etc. during the manufacturing process of the SiC bonded substrate and repeatedly supplied during the bonding of the SiC bonded substrate. Therefore, in a state where the contour 110 of the bonding surface is recessed and the side surface of the SiC single crystal transfer composite substrate 100 is recessed and becomes smaller in a groove shape, that is, there is a recessed portion 111 formed by the circumferential contour 110 of the bonding surface between the SiC single crystal substrate 200 and the first SiC polycrystalline substrate 300, the grinding chips, grinding powder, etc. of the substrate generated during grinding are likely to remain in the groove-shaped recessed portion 111 even if the SiC single crystal transfer composite substrate 100 is washed, and may become a dust source in the process of manufacturing the SiC bonded substrate.

[0054] Therefore, the side surface 112 of the first SiC polycrystalline substrate 300 may be ground by performing the side surface grinding step (S3) described later, for example, Figure 4 As shown in the composite substrate 101 for SiC single crystal transfer in (b), a slope 310 is formed on the outer periphery of the first SiC polycrystalline substrate 300. Since the recess 111 disappears by forming the slope 310, the dust source can be removed. Preferably, the angle A formed by the bonding surface 120 of the composite substrate 101 for SiC single crystal transfer and the slope 310 is 30° to 60° so that the strength of the first SiC polycrystalline substrate 300 is not weakened, and is preferably 45°. In addition, the angle B formed by the release surface 320 of the first SiC polycrystalline substrate 300 and the slope 310 is set to an obtuse angle, thereby preventing defects of the first SiC polycrystalline substrate 300 in the end 330 formed by the release surface 320 of the first SiC polycrystalline substrate 300 and the slope 310.

[0055] In addition, the shape in which the recessed portion 111 disappears is not limited to the SiC single crystal transfer composite substrate 101, and examples thereof include Figure 4 The SiC single crystal transfer composite substrate 102 shown in (c) Figure 4The SiC single crystal transfer composite substrate 103 shown in (d) in FIG. The SiC single crystal transfer composite substrate 102 is chamfered in such a way that the side surface 113 forms a semicircle together with the SiC single crystal substrate 200 and the first SiC polycrystalline substrate 300. In addition, the SiC single crystal transfer composite substrate 103 has a side surface shape similar to that of the SiC single crystal transfer composite substrate 101, but in the SiC single crystal transfer composite substrate 101, only the side surface 112 of the first SiC polycrystalline substrate 300 is ground to form a slope 310, while in the SiC single crystal transfer composite substrate 103, the entire side surface 112 of the first SiC polycrystalline substrate 300 and a portion of the side surface 114 of the SiC single crystal substrate 200 are ground to form a slope 130.

[0056] In the case of the composite substrate 100 for SiC single crystal transfer, neither the contour line of the circumference of the release surface 320 nor the contour line of the circumference of the bonding surface 120 is the maximum value of the contour line of the circumference of the first SiC polycrystalline substrate 300, and the maximum value is the contour line 350 ( Figure 4 In this way, when the contour line of the circumference of the bonding surface 120 is not the above-mentioned maximum value, the recessed portion 111 is formed.

[0057] In contrast, the common features of the SiC single crystal transfer composite substrate 101, the SiC single crystal transfer composite substrate 102, and the SiC single crystal transfer composite substrate 103 are: the contour line of the circumference of the release surface 320 of the first SiC polycrystalline substrate 300 is the minimum value of the contour line of the circumference of the first SiC polycrystalline substrate 300, and the contour line of the circumference of the bonding surface 120 of the first SiC polycrystalline substrate 300 is the maximum value of the contour line of the circumference of the first SiC polycrystalline substrate 300.

[0058] That is, the contour line passing through the maximum value of the circumference of the first SiC polycrystalline substrate 300 is identical to the contour line of the circumference of the bonding surface 120 between the SiC single crystal substrate 200 and the first SiC polycrystalline substrate 300 , so that no recess 111 exists in the SiC single crystal transfer composite substrate.

[0059] Alternatively, the end 330 of the release surface 320 of the first SiC polycrystalline substrate 300 may be chamfered so that the first SiC polycrystalline substrate 300 is not damaged by impact or the like.

[0060] [Method for manufacturing a composite substrate for SiC single crystal transfer]

[0061] Next, a method for manufacturing the SiC single crystal transfer composite substrates 100 to 103 of the present invention will be described. The SiC single crystal transfer composite substrate 100 can be manufactured by Figure 1 The first activation step (S1) and the first room temperature bonding step (S2) are manufactured.

[0062] <First Activation Step (S1)>

[0063] The first activation step is a step of irradiating the first bonding target surface 260 of the SiC single crystal substrate 200 and the bonding target surface 360 ​​of the first SiC polycrystalline substrate 300 with a high-speed atomic beam to activate these bonding target surfaces.

[0064] like Figure 2 As shown, the SiC single crystal substrate 200 and the first SiC polycrystalline substrate 300 are attracted by the electrostatic chuck 500 and set in the chamber 400. Next, the electrostatic chuck 500 is moved to align the relative positions of the SiC single crystal substrate 200 and the first SiC polycrystalline substrate 300. The alignment is performed so that the SiC single crystal substrate 200 and the first SiC polycrystalline substrate 300 can be contacted and bonded in the first room temperature bonding process described later in the correct position relationship. Next, the chamber 400 is made into a vacuum state. The vacuum degree in the chamber 400 can also be, for example, 1×10 -4 ~1×10 -7 Pa around.

[0065] Next, a FAB gun (Fast Atomic Beam Gun) 410 is used to irradiate the bonding target surface 360 ​​of the first SiC polycrystalline substrate 300 and the first bonding target surface 260 of the SiC single crystal substrate 200 with a neutral element beam 411 of argon (Ar) as a high-speed atomic beam. The neutral element beam 411 of argon (Ar) is uniformly irradiated on the entire surface of the first bonding target surface 260 and the entire surface of the bonding target surface 360. Since the FAB gun is used to make atoms or molecules collide with the surface of the substrate, the oxide and adsorption layer on the surface of the substrate can be removed by sputtering, so the oxide film and adsorption layer of the first bonding target surface 260 and the bonding target surface 360 ​​can be removed to expose the bonding bond. The state in which the oxide film and adsorption layer are removed and the bonding bond is exposed is called an active state. In addition, since the irradiation of the neutral element beam 411 is a process performed in a vacuum, the first bonding target surface 260 and the bonding target surface 360 ​​can maintain an active state without being oxidized. Here, an argon (Ar) ion beam or an argon (Ar) neutral atom beam is used as the high-speed atomic beam.

[0066] In addition, the SiC single crystal substrate 200 and the first SiC polycrystalline substrate 300 are preferably made of a material that has been subjected to chamfering of the side corners, double-side polishing, grinding, cleaning, etc. in advance before the first activation step to remove the processed altered layer and undulations on the surface of the first SiC polycrystalline substrate 300.

[0067] <First Room Temperature Bonding Step (S2)>

[0068] The first room temperature bonding process is a process of bonding the first bonding target surface 260 of the SiC single crystal substrate 200 and the bonding target surface 360 ​​of the first SiC polycrystalline substrate 300 at room temperature after the first activation process. It is a process of directly bonding the first bonding target surface 260 and the bonding target surface 360 ​​by covalent bonds. For direct bonding, a bonding method that applies heat to the substrates, such as a bonding method of exposing under conditions such as 1100°C for 2 hours or a bonding method of melting at a temperature of 2000°C or above, is often used. However, in the method of applying heat, the production efficiency is poor, and it is difficult to bond the positions of each substrate with high precision during heating. In addition, if the heating temperature exceeds 2000°C, the silicon in SiC decreases and forms voids, which deteriorates the conductivity. In the present invention, by setting the bonding method to bonding at room temperature, it is possible to improve productivity, maintain conductivity, and bond the bonding positions of the SiC single crystal substrate 200 and the first SiC polycrystalline substrate 300 with high precision.

[0069] like Figure 3 As shown, by moving the electrostatic chuck 500, the first bonding target surface 260 of the SiC single crystal substrate 200 and the bonding target surface 360 ​​of the first SiC polycrystalline substrate 300 are brought into contact and pressed tightly in a vacuum state in the chamber 400. The bonding bonds of the first bonding target surface 260 and the bonding target surface 360 ​​existing in the active state are connected to each other, and the SiC single crystal substrate 200 and the first SiC polycrystalline substrate 300 can be bonded. Thus, the SiC single crystal transfer composite substrate 100 having a structure in which the SiC single crystal substrate 200 and the first SiC polycrystalline substrate 300 are bonded is formed. In addition, the room temperature refers to 20°C to 30°C.

[0070] <Side grinding process (S3)>

[0071] The present invention may also include a side grinding process, which is the following process: after the first room temperature bonding process, the side surface 112 of the first SiC polycrystalline substrate 300 is ground to remove the recess 111 formed by the side surface 114 of the SiC single crystal substrate 200, the side surface 112 of the first SiC polycrystalline substrate 300, and the circumferential contour 110 of the bonding surface 120 between the SiC single crystal substrate 200 and the first SiC polycrystalline substrate 300.

[0072] The side grinding step is preferably performed after the first SiC polycrystalline substrate 300 is bonded to the SiC single crystal substrate 200, that is, preferably performed after the first room temperature bonding step. If the side surface 112 of the first SiC polycrystalline substrate 300 before bonding is ground, the angle A ( Figure 4(b)) in the figure becomes an acute angle, and there is a risk that the first SiC polycrystalline substrate 300 may be damaged by some impact or contact with some object before being bonded to the SiC single crystal substrate 200 .

[0073] In this step, the SiC single crystal transfer composite substrate 100 ( Figure 4 The side surface of (a)) becomes the SiC single crystal transfer composite substrates 101 to 103 ( Figure 4 (b)~ Figure 4 It can be ground into the shape of (d)).

[0074] Specifically, the side surface can be ground using a chamfering machine or a grinding device. For example, the side surface 112 of the first SiC polycrystalline substrate 300 can be ground by any of the methods shown in the following (1) to (3). (1) After the wafer-shaped SiC single crystal transfer composite substrate 100 is rotated with its center as the rotation axis, the grindstone of the grinding wheel that rotates in the same manner is brought into contact with the side surface 112 of the first SiC polycrystalline substrate 300 for grinding. (2) The side surface 112 of the rotated wafer-shaped SiC single crystal transfer composite substrate 100 is brought into contact with a grindstone that does not rotate for grinding. (3) The grindstone of the grinding wheel that rotates and revolves around the bonded substrate is brought into contact with the side surface 112 of the SiC single crystal transfer composite substrate 100 for grinding.

[0075] [Method for manufacturing SiC bonding substrate]

[0076] Next, the method for manufacturing the SiC bonding substrate of the present invention is described. The SiC bonding substrate can be manufactured by Figure 1 The SiC single crystal transfer composite substrate 100 is used as an example, but a SiC bonded substrate can be manufactured even if SiC single crystal transfer composite substrates 101 to 103 are used.

[0077] <Hydrogen ion implantation layer forming step (S4)>

[0078] The hydrogen ion implantation layer forming step is a step of implanting hydrogen ions into the second bonding target surface 270 of the SiC single crystal substrate 200 in the SiC single crystal transfer composite substrate 100 to form a hydrogen ion implantation layer 600 inside the SiC single crystal substrate 200 .

[0079] When hydrogen ions are implanted into the SiC single crystal substrate 200, the hydrogen ions reach a depth corresponding to the incident energy and are distributed at a high concentration. Figure 5As shown in the schematic side view of the SiC single crystal transfer composite substrate 100, a hydrogen ion implantation layer 600 indicated by a dotted line is formed at a predetermined depth from the second bonding target surface 270. For example, the hydrogen ion implantation layer 600 is formed at a depth of about 0.5 to 1.0 μm from the second bonding target surface 270.

[0080] <Second Activation Step (S5)>

[0081] The second activation step is a step of irradiating the second bonding target surface 270 of the SiC single crystal substrate 200 and the bonding target surface 770 of the second SiC polycrystalline substrate 700 with a high-speed atomic beam to activate these bonding target surfaces.

[0082] The basic process steps are the same as the first activation process. Figure 6 As shown, the composite substrate 100 for SiC single crystal transfer and the second SiC polycrystalline substrate 700 are attracted by the electrostatic chuck 500 and set in the chamber 400. Next, the electrostatic chuck 500 is moved to align the relative positions of the composite substrate 100 for SiC single crystal transfer and the second SiC polycrystalline substrate 700. The alignment is performed in a manner that the two substrates can contact with each other in a correct positional relationship through the second room temperature bonding process described later. Next, the chamber 400 is made into a vacuum state. The vacuum degree in the chamber 400 can also be, for example, 1×10 -4 ~1×10 -7 Pa around.

[0083] Next, the second bonding target surface 270 of the SiC single crystal substrate 200 and the bonding target surface 770 of the second SiC polycrystalline substrate 700 are irradiated with a neutral element beam 411 of argon (Ar) as a high-speed atomic beam using a FAB gun (Fast Atomic Beam Gun) 410. The neutral element beam 411 of argon (Ar) is uniformly irradiated on the entire surface of the second bonding target surface 270 and the entire surface of the bonding target surface 770. Since the FAB gun is used to make atoms or molecules collide with the surface of the substrate, the oxide and adsorption layer on the surface of the substrate can be removed by sputtering, so the oxide film and adsorption layer of the second bonding target surface 270 and the bonding target surface 770 can be removed to expose the bonding bond. The state in which the oxide film and adsorption layer are removed and the bonding bond is exposed is called an active state. In addition, since the irradiation of the neutral element beam 411 is a process performed in a vacuum, the second bonding target surface 270 and the bonding target surface 770 can maintain an active state without being oxidized.

[0084] <Second SiC Polycrystalline Substrate 700>

[0085] The second SiC polycrystalline substrate 700 is a supporting substrate in the SiC bonding substrate. As the second SiC polycrystalline substrate 700, for example, a 3C-SiC polycrystalline substrate obtained by forming a SiC polycrystalline film by chemical vapor deposition can be used. The shape of the second SiC polycrystalline substrate 700 can be almost the same as the shape of the composite substrate 100 for SiC single crystal transfer, for example, a roughly disk-shaped substrate with an orientation plane, and a substrate with a diameter of 4 to 8 inches can be used. In addition, the shape is not limited to a disk shape, and can also be a polygonal shape.

[0086] Furthermore, the thickness of the second SiC polycrystalline substrate 700 may be a general thickness of a support substrate as a SiC bonding substrate, for example, 300 μm to 500 μm. In addition, the volume resistivity of the second SiC polycrystalline substrate 700 may be 0.005 to 10 Ω·cm in consideration of electrical conductivity, or 10 Ω·cm, which is a general volume resistivity of SiC. 5 SiC polycrystalline substrate with a resistance of Ω·cm or above.

[0087] In addition, the second SiC polycrystalline substrate 700 is preferably one that has been subjected to chamfering of the side corners, double-side polishing, grinding, cleaning, etc., to remove a processed deteriorated layer and undulations on the surface of the second SiC polycrystalline substrate 700 before the second activation step.

[0088] <Second Room Temperature Bonding Step (S6)>

[0089] The second room temperature bonding step is a step of bonding the second bonding target surface 270 of the SiC single crystal substrate 200 and the bonding target surface 770 of the second SiC polycrystalline substrate 700 at room temperature after the second activation step. The second bonding target surface 270 and the bonding target surface 770 are directly bonded by covalent bonds.

[0090] The basic process steps are the same as the first room temperature bonding process. Figure 7 As shown, by moving the electrostatic chuck 500, the second bonding target surface 270 of the SiC single crystal substrate 200 and the bonding target surface 770 of the second SiC polycrystalline substrate 700 are brought into contact in a vacuum state in the chamber 400. The bonding bonds of the second bonding target surface 270 and the bonding target surface 770 existing in the active state are connected to each other, and the SiC single crystal transfer composite substrate 100 and the second SiC polycrystalline substrate 700 can be bonded. In addition, the normal temperature refers to 20°C to 30°C.

[0091] <Peeling step (S7)>

[0092] The peeling step is a step of peeling the SiC single crystal substrate 200 along the hydrogen ion implantation layer 600 after the second room temperature bonding step to transfer the SiC single crystal thin film 280 to the second SiC polycrystalline substrate 700 .

[0093] In the peeling step, heat is applied to the SiC single crystal substrate 200 to form a microbubble layer in the hydrogen ion implantation layer 600 , and a SiC single crystal thin film 280 having a thickness of about 0.5 to 1.0 μm is transferred to the second SiC polycrystalline substrate 700 with the microbubble layer as a peeling surface to form a SiC bonded substrate 800 .

[0094] Specifically, the SiC single crystal transfer composite substrate 100 and the second SiC polycrystalline substrate 700 bonded to each other are heated to about 800° C. or more. The peeling atmosphere can be at least one of an inert gas such as argon (Ar), nitrogen (N), or a vacuum atmosphere. The peeling process can be performed using rapid thermal annealing (RTA) and a furnace. Thus, the SiC single crystal substrate 200 can be separated through the hydrogen ion implantation layer 600. Figure 8 A schematic side view of the SiC single crystal transfer composite substrate 100 after the peeling step ( Figure 8 (a)) and a schematic side view of the SiC bonding substrate 800 ( Figure 8 (b) in the figure.

[0095] The method for manufacturing a SiC bonding substrate of the present invention may be a method for manufacturing a plurality of SiC bonding substrates 800 by repeatedly using a SiC single crystal transfer composite substrate 100 after a stripping process, or may be a method for repeatedly performing a hydrogen ion implantation layer forming process, a second activation process, a second room temperature bonding process, and a stripping process until the thickness of the SiC single crystal transfer composite substrate 100 having the SiC single crystal substrate 200 becomes less than 300 μm.

[0096] <Second bonding target surface polishing step (S8)>

[0097] When the SiC single crystal transfer composite substrate 100 is repeatedly used after the peeling step, the second bonding target surface polishing step may be performed. This step is to polish the second bonding target surface 270 ( Fig. 9 ) Mirror polishing step. Mirror polishing can be performed by grinding or polishing the second bonding target surface 270 through mechanical polishing or the like, or can be performed by CMP method.

[0098] In the steps S4 to S8 of the present invention, the SiC single crystal transfer composite substrate 100, the second SiC polycrystalline substrate 700, and the SiC bonding substrate 800 may also be held by an electrostatic chuck. In addition, for example, since the second activation step (S5) and the second room temperature bonding step (S6) are performed under reduced pressure (1×10 -4 ~1×10 -7Pa or so), so a vacuum chuck cannot be used to hold the SiC single crystal transfer composite substrate 100, the second SiC polycrystalline substrate 700, and the SiC bonded substrate 800. Therefore, a mechanical chuck method or an electrostatic chuck method is used, but in the mechanical chuck method, local stress is applied to these substrates during holding, not only can these substrates not be held flat, but also cracks and flaws are generated in these substrates due to repeated use, and these cracks and flaws may become dust sources. Therefore, in order to avoid the generation of cracks and flaws, it is preferred to use an electrostatic chuck method that can hold these substrates on the entire surface without applying pressure to these substrates during transportation and holding of these substrates.

[0099] Example

[0100] Next, the present invention will be described in more detail with reference to examples thereof; however, the present invention is not limited to the following examples at all.

[0101] [Manufacturing of composite substrate for SiC single crystal transfer]

[0102] 〈Substrate used〉

[0103] (SiC Single Crystal Substrate 200)

[0104] As the SiC single crystal substrate 200, a conductive SiC single crystal substrate of 4H polytype with a main surface orientation of <0001> and a diameter of 150 mm and a thickness of 350 μm was prepared, the side surface of which was chamfered into an R shape, and both the first bonding object surface 260 and the opposite surface of the substrate were mirror-polished and cleaned.

[0105] (First SiC Polycrystalline Substrate A (Volume Resistivity 3Ω·cm))

[0106] As the first SiC polycrystalline substrate 300, a first SiC polycrystalline substrate A having a diameter of 150 mm and a thickness of 350 μm and having conductivity was prepared, the side surfaces of which were chamfered into an R shape, and both the bonding target surface 360 ​​and the opposing surface of the substrate were mirror-polished and cleaned. The volume resistivity of the first SiC polycrystalline substrate A was 3 Ω·cm at 25°C.

[0107] (First SiC polycrystalline substrate B (volume resistivity 10 5 Ω·cm))

[0108] In addition, for comparison with the first SiC polycrystalline substrate 300, a first SiC polycrystalline substrate B having a volume resistivity of 100 Ω·cm at 25° C. was prepared. Similar to the first SiC polycrystalline substrate A, the side faces were chamfered into an R shape, and both surfaces of the substrate were mirror-polished and cleaned, and the substrate was a cubic SiC polycrystalline substrate having a diameter of 150 mm and a thickness of 350 μm.

[0109] <Example 1>

[0110] Using the SiC single crystal substrate 200 and the first SiC polycrystalline substrate A as the first SiC polycrystalline substrate 300, the following first activation step (S1) and first room temperature bonding step (S2) were performed to manufacture a plurality of SiC single crystal transfer composite substrates 100 having a thickness of 700 μm of Example 1.

[0111] (First Activation Step (S1))

[0112] like Figure 2 As shown, the SiC single crystal substrate 200 and the first SiC polycrystalline substrate 300 are attracted by the electrostatic chuck 500 and placed in the chamber 400. Next, the electrostatic chuck 500 is moved to align the relative positions of the SiC single crystal substrate 200 and the first SiC polycrystalline substrate 300 so that these substrates can contact with each other in a correct positional relationship through the first room temperature bonding process. Next, the chamber 400 is made 2×10 -6 Pa vacuum state.

[0113] Then, under the above-mentioned vacuum state, a FAB gun 410 is used to uniformly irradiate the entire surface of the first bonding object surface 260 and the entire surface of the bonding object surface 360 ​​of the first SiC polycrystalline substrate 300 and the first bonding object surface 260 of the SiC single crystal substrate 200 with a neutral atom beam 411 of argon gas, thereby removing the oxide film and adsorption layer of the first bonding object surface 260 and the bonding object surface 360 ​​to expose the bonding bonds and put them into an active state.

[0114] (First Room Temperature Bonding Step (S2))

[0115] Maintain vacuum at room temperature, such as Figure 3 As shown, electrostatic chuck 500 is moved in chamber 400, so that first bonding target surface 260 of SiC single crystal substrate 200 and bonding target surface 360 ​​of first SiC polycrystalline substrate 300 are brought into contact in a vacuum state in chamber 400 and directly bonded by covalent bonds, thereby manufacturing composite substrate 100 for SiC single crystal transfer.

[0116] <Example 2>

[0117] The following side grinding step was further performed on the SiC single crystal transfer composite substrate 100 of Example 1 to remove the recessed portion 111 , thereby manufacturing a plurality of SiC single crystal transfer composite substrates 101 of Example 2 each having a thickness of 700 μm.

[0118] (Side grinding process (S3))

[0119] The side surface of the first SiC polycrystalline substrate 300 of the composite substrate for SiC single crystal transfer 100 of Example 1 was ground by a chamfering machine using diamond plated grindstones of mesh size #400 and #800, thereby forming a slope 310 with an angle A of 45°.

[0120] <Comparative Example 1>

[0121] A plurality of SiC single crystal transfer composite substrates having a thickness of 700 μm of Comparative Example 1 were manufactured by the same method as in Example 1, except that SiC polycrystalline substrate B was used instead of SiC polycrystalline substrate A. In addition, in the first activation step, the first room temperature bonding step, the second activation step, and the second room temperature bonding step, a mechanical chuck was used instead of an electrostatic chuck.

[0122] <Comparative Example 2>

[0123] A plurality of SiC single crystal substrates 200 are prepared without bonding any of the SiC polycrystalline substrate A and the SiC polycrystalline substrate B to the SiC single crystal substrate 200 , and are used in the following production of a SiC bonded substrate.

[0124] [Manufacturing of SiC Bonding Substrate]

[0125] For each of the SiC single crystal transfer composite substrate 100 of Example 1, the SiC single crystal transfer composite substrate 101 of Example 2, the SiC single crystal transfer composite substrate of Comparative Example 1, and the SiC single crystal substrate 200 of Comparative Example 2, the following steps S4 to S9 are performed to bond the following second SiC polycrystalline substrate 700 to manufacture a SiC bonded substrate.

[0126] (Second SiC Polycrystalline Substrate 700 (Volume Resistivity 3Ω·cm))

[0127] As the second SiC polycrystalline substrate 700, the same substrate as the first SiC polycrystalline substrate A was used. That is, a cubic SiC polycrystalline substrate with a diameter of 150 mm and a thickness of 350 μm, which was processed into an R-shaped side chamfer, and both surfaces of the substrate were mirror-polished and cleaned, and had a volume resistivity of 3 Ω·cm at 25°C.

[0128] (Hydrogen Ion Implantation Layer Formation Step (S4))

[0129] Hydrogen ions were implanted into the second bonding target surface 270 of the SiC single crystal substrate 200 in the SiC single crystal transfer composite substrate 100 of Example 1, and a hydrogen ion implantation layer 600 was formed at a depth of 0.8 μm from the second bonding target surface 270 .

[0130] Similarly, for the SiC single crystal transfer composite substrate 101 of Example 2, the SiC single crystal transfer composite substrate of Comparative Example 1, and the SiC single crystal substrate 200 of Comparative Example 2, a hydrogen ion implantation layer was formed at a depth of 0.8 μm.

[0131] (Second Activation Step (S5))

[0132] like Figure 7 As shown, the composite substrate 100 for SiC single crystal transfer and the second SiC polycrystalline substrate 700 are attracted by the electrostatic chuck 500 and placed in the chamber 400. Next, the electrostatic chuck 500 is moved to align the relative positions of the composite substrate 100 for SiC single crystal transfer and the second SiC polycrystalline substrate 700 so that the two substrates can contact with each other in a correct positional relationship through the second room temperature bonding process. Next, the chamber 400 is made to have a 2×10 -6 Pa vacuum state.

[0133] Next, using a FAB gun 410, a neutral atom beam 411 of argon gas is uniformly irradiated on the entire surface of the second bonding object surface 270 and the entire surface of the bonding object surface 770 of the second SiC single crystal substrate 200, thereby removing the oxide film and adsorption layer on the second bonding object surface 270 and the bonding object surface 770 to expose the bonding bonds and put them into an active state.

[0134] The second activation step was similarly performed on the SiC single crystal transfer composite substrate 101 of Example 2, the SiC single crystal transfer composite substrate of Comparative Example 1, and the SiC single crystal substrate 200 of Comparative Example 2.

[0135] (Second Room Temperature Bonding Step (S6))

[0136] Maintain vacuum at room temperature, such as Figure 7 As shown, the electrostatic chuck 500 is moved in the chamber 400, and the second bonding target surface 270 of the SiC single crystal substrate 200 and the bonding target surface 770 of the second SiC polycrystalline substrate 700 are brought into contact in a vacuum state in the chamber 400, and directly bonded by covalent bonds to obtain a bonded substrate.

[0137] The second room temperature bonding step was similarly performed on the SiC single crystal transfer composite substrate 101 of Example 2, the SiC single crystal transfer composite substrate of Comparative Example 1, and the SiC single crystal substrate 200 of Comparative Example 2 to obtain bonded substrates.

[0138] (Peeling Step (S8))

[0139] The bonded substrate was heated to 1100° C. in an inert atmosphere filled with argon gas using a furnace to form a micro bubble layer in the hydrogen ion implantation layer 600, the SiC single crystal substrate 200 was separated through the micro bubble layer, and the thin SiC single crystal film 280 with a thickness of 0.8 μm was transferred to the second SiC polycrystalline substrate 700, thereby obtaining a SiC bonded substrate 800 ( Fig. 9 ).

[0140] The SiC single crystal transfer composite substrate 101 of Example 2, the SiC single crystal transfer composite substrate of Comparative Example 1, and the SiC single crystal substrate 200 of Comparative Example 2 were subjected to the same separation step to obtain SiC bonded substrates.

[0141] [Evaluation 1: Evaluation of transportability]

[0142] The SiC single crystal transfer composite substrate 100 after the peeling step was repeatedly used, and the steps S4 to S10 were repeatedly performed to repeatedly manufacture the SiC bonded substrate 800. Furthermore, the second bonding target surface polishing step (S8) was performed as follows.

[0143] (Second Bonding Surface Polishing Step (S8))

[0144] After the peeling process, the second bonding target surface 270 of the SiC single crystal transfer composite substrate 100 was mirror-polished by CMP before the hydrogen ion implantation layer formation process. After the peeling process, the SiC single crystal transfer composite substrate 101 of Example 2, the SiC single crystal transfer composite substrate of Comparative Example 1, and the SiC single crystal substrate 200 of Comparative Example 2 were mirror-polished in the same manner.

[0145] <result>

[0146] (SiC Single Crystal Transfer Composite Substrate 100 and SiC Single Crystal Transfer Composite Substrate 101 of Examples 1 and 2)

[0147] In the SiC single crystal transfer composite substrate 100 and SiC single crystal transfer composite substrate 101 of Examples 1 and 2, even if the thickness of the SiC single crystal substrate 200 is thinned from the initial 350 μm to 140 μm through transfer, since the warping of the substrate based on hydrogen ion injection is suppressed within 320 μm, when the SiC single crystal transfer composite substrate 100 and SiC single crystal transfer composite substrate 101 are transported, no transportation errors of the SiC single crystal transfer composite substrate 100 and SiC single crystal transfer composite substrate 101 will occur.

[0148] (Comparative Example 1 SiC Single Crystal Transfer Composite Substrate)

[0149] Even if the thickness of the SiC single crystal substrate 200 is reduced from the initial 350 μm to 140 μm by transfer, the warpage of the substrate is suppressed to within 320 μm, so that when the composite substrate for SiC single crystal transfer is transported, there is no transport error of the composite substrate for SiC single crystal transfer.

[0150] (SiC Single Crystal Substrate 200 of Comparative Example 2)

[0151] Since the SiC single crystal substrate 200 is not bonded to the first SiC polycrystalline substrate 300 , if the thickness of the SiC single crystal substrate 200 is reduced from the initial 350 μm to less than 300 μm by transfer, the substrate warps by more than 1000 μm, causing a transport error of the SiC single crystal substrate 200 .

[0152] Based on the above results, it can be seen that the SiC single crystal transfer composite substrate 100 and SiC single crystal transfer composite substrate 101 of Examples 1 and 2 can reduce the loss of SiC single crystal substrate 200 and improve the manufacturing efficiency of SiC bonded substrate 800 because they can be further reused in the manufacture of SiC bonded substrate 800.

[0153] [Evaluation 2: Bonding Properties of the SiC Single Crystal Thin Film 280 and the Second SiC Polycrystalline Substrate 700]

[0154] The defective bonding between the SiC single crystal thin film 280 and the second SiC polycrystalline substrate 700 was analyzed using a SiC wafer defect inspection apparatus SICA88 manufactured by Lasertec Corporation.

[0155] As a result, when the composite substrate 101 for SiC single crystal transfer of Example 2 is used, the generation of dust can be suppressed by removing the recess 111, and by making the volume resistivity of the first SiC polycrystalline substrate 300 3Ω·cm, grinding chips, grinding powder, etc. are not easy to adhere to the first SiC polycrystalline substrate 300. As a result, compared with the case of using the SiC single crystal substrate 200 of Comparative Example 1, 80% of bonding failures can be suppressed.

[0156] Moreover, when the SiC single crystal transfer composite substrate 100 of Example 1 is used, by making the volume resistivity of the first SiC polycrystalline substrate 300 3Ω·cm, grinding chips, grinding powder, etc. are not easy to adhere to the first SiC polycrystalline substrate 300. As a result, compared with the case of using the SiC single crystal substrate 200 of Comparative Example 1, 50% of bonding failures can be suppressed.

[0157] In addition, when the SiC single crystal transfer composite substrate of Comparative Example 1 was used, the recess 111 existed, and the first SiC polycrystalline substrate had a volume resistivity of 100 Ω·cm and high insulation, so that grinding chips, grinding powder, etc. easily adhered to the first SiC polycrystalline substrate, and bonding failure could not be suppressed.

[0158] Description of Reference Numerals

[0159] 100, 101, 102, 103: composite substrate for SiC single crystal transfer;

[0160] 110: outline;

[0161] 111: concave part;

[0162] 112: side;

[0163] 113: Side;

[0164] 114: side;

[0165] 120: joint surface;

[0166] 200: SiC single crystal substrate;

[0167] 201: Single-sided;

[0168] 260: first bonding object surface;

[0169] 270: second bonding object surface;

[0170] 280: SiC single crystal thin film;

[0171] 300: a first SiC polycrystalline substrate;

[0172] 301: Single-sided;

[0173] 310: Slope;

[0174] 320: Release surface;

[0175] 330: end;

[0176] 350: contour line;

[0177] 360: Join the object surface;

[0178] 400: Chamber;

[0179] 410: FAB gun;

[0180] 411: Neutral element beam;

[0181] 500: electrostatic chuck;

[0182] 600: hydrogen ion implantation layer;

[0183] 700: a second SiC polycrystalline substrate;

[0184] 770: Joining object faces;

[0185] 800: SiC bonding substrate;

[0186] 900: doping layer;

[0187] A: Angle;

[0188] B: Angle.

Claims

1. A composite substrate for SiC single crystal transfer, wherein: The composite substrate for SiC single crystal transfer comprises a SiC single crystal substrate and a first SiC polycrystalline substrate having a volume resistivity of 10 Ω·cm or less. One surface of the SiC single crystal substrate is directly bonded to one surface of the first SiC polycrystalline substrate through a covalent bond.

2. The composite substrate for SiC single crystal transfer according to claim 1, wherein: The first SiC polycrystalline substrate is in a wafer shape, and the maximum value of a circumferential contour line of the first SiC polycrystalline substrate is the same as a circumferential contour line of a bonding surface between the SiC single crystal substrate and the first SiC polycrystalline substrate.

3. A method for manufacturing a composite substrate for SiC single crystal transfer, which is the method for manufacturing a composite substrate for SiC single crystal transfer according to claim 1, wherein: The method for manufacturing the composite substrate for SiC single crystal transfer comprises: a first activation step, in which a high-speed atomic beam is irradiated onto a first bonding target surface of the SiC single crystal substrate and a bonding target surface of the first SiC polycrystalline substrate to activate these bonding target surfaces; and A first room temperature bonding step, in which after the first activation step, the first bonding target surface of the SiC single crystal substrate and the bonding target surface of the first SiC polycrystalline substrate are bonded at room temperature in a manner that the first bonding target surface is directly bonded by covalent bonds.

4. The method for manufacturing a composite substrate for SiC single crystal transfer according to claim 3, wherein: The manufacturing method of the composite substrate for SiC single crystal transfer includes a side grinding process. In the side grinding process, after the first room temperature bonding process, the side of the first SiC polycrystalline substrate is ground to remove the recessed portion formed by the side of the SiC single crystal substrate, the side of the first SiC polycrystalline substrate, and the contour of the circumference of the bonding surface between the SiC single crystal substrate and the first SiC polycrystalline substrate.

5. A method for manufacturing a SiC bonding substrate, wherein: The method for manufacturing the SiC bonding substrate comprises: a hydrogen ion implantation layer forming step, in which hydrogen ions are implanted into the second bonding target surface of the SiC single crystal substrate in the composite substrate for SiC single crystal transfer according to claim 1 to form a hydrogen ion implantation layer inside the SiC single crystal substrate; a second activation step, in which the second bonding target surface of the SiC single crystal substrate and the bonding target surface of the second SiC polycrystalline substrate are irradiated with a high-speed atomic beam to activate these bonding target surfaces; a second room temperature bonding step, in which, after the second activation step, the second bonding target surface of the SiC single crystal substrate and the bonding target surface of the second SiC polycrystalline substrate are bonded at room temperature in a manner that the second bonding target surface is directly bonded to the second SiC polycrystalline substrate by covalent bonds; as well as a peeling step, in which, after the second room temperature bonding step, the SiC single crystal substrate is peeled off along the hydrogen ion implantation layer, and the SiC single crystal thin film is transferred to the second SiC polycrystalline substrate, The SiC single crystal transfer composite substrate and the second SiC polycrystalline substrate are held by an electrostatic chuck, and the second SiC polycrystalline substrate is provided with the SiC single crystal thin film.

6. The method for manufacturing a SiC bonded substrate according to claim 5, wherein: The manufacturing method is a method of repeatedly using the SiC single crystal transfer composite substrate after the peeling step to manufacture a plurality of the SiC bonded substrates. The hydrogen ion implantation layer forming step, the second activation step, the second room temperature bonding step, and the peeling step are repeatedly performed until the thickness of the SiC single crystal substrate of the SiC single crystal transfer composite substrate becomes less than 140 μm.

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