Substrate peeling method and method for manufacturing an epitaxial layer-containing structure

Abstract

The objective is to provide a substrate peeling method and a method for manufacturing an epitaxial layer-containing structure that can stably peel off the epitaxial growth layer from the growth substrate, reduce damage to the growth substrate, and increase the number of times the growth substrate can be reused. [Solution] A substrate peeling method comprising the steps of: forming an epitaxial layer having a band gap larger than the band gap of the semiconductor substrate on the surface of the semiconductor substrate to produce a laminated structure; irradiating the laminated structure from above the epitaxial layer with a laser having a wavelength range that penetrates the epitaxial layer but does not penetrate the semiconductor substrate to form a peeling layer near the interface between the semiconductor substrate and the epitaxial layer; and separating the semiconductor substrate and the epitaxial layer at the peeling layer, wherein the focal position of the laser is within ±45 μm of the depth direction of the laminated structure from the interface.

Description

Technical Field

[0001] The present invention relates to a substrate peeling method and a method for manufacturing an epitaxial layer-containing structure.

Background Art

[0002] Due to the characteristic of GaN having a high saturated electron velocity, it is possible to fabricate devices capable of high-frequency operation. Also, due to its high breakdown electric field, it is possible to operate at high power. Moreover, weight reduction, miniaturization, and low power consumption can be expected. As a substrate for epitaxial growth for fabricating GaN devices, a single-crystal silicon substrate is the most inexpensive and advantageous for increasing the diameter.

[0003] In recent years, due to the demand for higher communication speeds and the accompanying higher output power, GaN HEMTs capable of operating at high frequencies and high powers have attracted attention. While being expected to be suitable for high-frequency and high-power operation, there is a problem that the device operation characteristics and reliability deteriorate due to heat generation during operation.

[0004] Therefore, as described in Patent Document 1, in GaN devices, as a method for cooling the device, using a diamond material having a high thermal conductivity as a heat dissipation substrate has been studied.

[0005] In order to bond only the GaN layer epitaxially grown on the Si substrate to the heat dissipation substrate, it is necessary to remove the Si substrate that serves as the growth substrate.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

[0007] Conventional technologies involve removing the Si substrate from the growth substrate using mechanical processes such as grinding and polishing, chemical processes such as dry etching and wet etching, or chemical-mechanical polishing, or a combination thereof. However, these methods have the problem that the Si substrate that will serve as the growth substrate is completely discarded during the removal process.

[0008] Furthermore, Patent Document 2 discloses a technique for separating a GaN layer from a substrate, such as a silicon, sapphire, SiC, or AlN polycrystalline wafer, by laser slicing, after epitaxial growth of a GaN layer on a substrate such as a silicon, sapphire, SiC, or AlN polycrystalline wafer as the base wafer. However, the specific conditions for the laser slicing are not shown, and it is unclear whether the base wafer can be reused.

[0009] Patent Document 3 discloses a technique for peeling off a group III nitride semiconductor seed crystal layer from a silicon single crystal thin film or silicon single crystal substrate by forming a peeling layer with laser irradiation. However, there were issues with the stability of the peeling process and the significant damage to the growth substrate when it was reused.

[0010] The present invention has been made to solve the above problems, and aims to provide a substrate peeling method and a method for manufacturing an epitaxial layer-containing structure that can stably peel off an epitaxial growth layer (hereinafter also referred to as "epitaxial layer") from an epitaxial growth substrate (hereinafter also simply referred to as "growth substrate" or "semiconductor substrate"), reduce damage to the growth substrate, and increase the number of times the growth substrate can be repeatedly used (reused). [Means for solving the problem]

[0011] The present invention has been made to achieve the above objective, and provides a substrate peeling method comprising the steps of: forming an epitaxial layer having a band gap larger than the band gap of a semiconductor substrate on the surface of a semiconductor substrate to produce a laminated structure; irradiating the laminated structure with a laser having a wavelength range that penetrates the epitaxial layer but does not penetrate the semiconductor substrate from above the epitaxial layer to form a peeling layer near the interface between the semiconductor substrate and the epitaxial layer; and separating the semiconductor substrate and the epitaxial layer at the peeling layer, wherein the focal position of the laser is within a range of ±45 μm from the interface in the depth direction of the laminated structure.

[0012] This substrate peeling method allows for the stable peeling of the epitaxial growth layer from the epitaxial growth substrate, reducing damage to the growth substrate and increasing the number of times the growth substrate can be reused.

[0013] In this case, the focal position of the laser can be set to a position within ±15 to 45 μm in the depth direction of the laminated structure from the interface.

[0014] This makes it possible to further reduce damage to the growth substrate and increase the number of times the growth substrate can be reused.

[0015] In this case, the process may include a step of placing a support substrate that holds the epitaxial layer on the epitaxial layer before the separation step.

[0016] By placing a support substrate to hold the epitaxial layer before peeling it off, the epitaxial layer can be made more stable after peeling.

[0017] In this case, a Si single crystal substrate can be used as the semiconductor substrate.

[0018] The Si single crystal substrate is inexpensive and is advantageous for increasing the diameter of the epitaxial wafer, so it is suitable for use as the growth substrate of the present invention.

[0019] At this time, the epitaxial layer can be made to contain any one or more of GaN, AlGaN, AlN, Ga2O3, and SiC.

[0020] Thereby, it can be made into a substrate for semiconductor devices excellent in suitability for high-frequency and high-output operations.

[0021] At this time, the wavelength of the laser can be 370 nm or more and 980 nm or less, and the laminated structure can be irradiated with it.

[0022] Thereby, the release layer can be formed more reliably.

[0023] At this time, the semiconductor substrate can be peeled off from the laminated structure having the semiconductor substrate and the epitaxial layer by the above-described substrate peeling method, and a method for manufacturing an epitaxial layer-containing structure for manufacturing a structure containing the epitaxial layer can be used.

[0024] Thereby, while increasing the number of times the growth substrate can be repeatedly used, an epitaxial layer-containing structure excellent in suitability for high-frequency and high-output operations can be manufactured.

Advantages of the Invention

[0025] As described above, according to the substrate peeling method of the present invention, the epitaxial growth layer can be stably peeled off from the epitaxial growth substrate, damage to the growth substrate can be reduced, and the number of times the growth substrate can be repeatedly used can be increased. The present invention also provides a method for manufacturing an epitaxial layer-containing structure using such a substrate peeling method.

Brief Description of the Drawings

[0026] [Figure 1]An example of the process flow of the substrate peeling method of the present invention is shown. [Figure 2] A schematic diagram of an example of a laminated structure according to the present invention is shown. [Figure 3] This shows the transmittance of Si, GaN, and SiC at each wavelength. [Figure 4] This diagram illustrates the formation of a delamination layer by laser irradiation. [Figure 5] A schematic diagram of an example of a structure including an epitaxial layer that has been planarized after delamination is shown ((a) structure, (b) structure bonded to a bonding substrate). [Figure 6] A schematic diagram of the semiconductor substrate after delamination is shown ((a) after delamination, (b) after reprocessing). [Modes for carrying out the invention]

[0027] The present invention will be described in detail below, but the present invention is not limited to these descriptions.

[0028] As described above, there was a need for a substrate peeling method that could stably peel the epitaxial growth layer from the epitaxial growth substrate, reduce damage to the growth substrate, and increase the number of times the growth substrate could be reused.

[0029] Here, "significant damage to the growth substrate" refers to a large amount of the growth substrate that needs to be removed after the epitaxial growth layer has been detached from the growth substrate before the growth substrate can be reused. Since the regeneration process of the growth substrate is carried out by removing the damaged layer remaining on the growth substrate after detachment, significant damage to the growth substrate will reduce the number of times the growth substrate can be reused.

[0030] As a result of diligent study on the above problems, the present inventors have found that a substrate peeling method comprising the steps of: forming an epitaxial layer having a band gap larger than the band gap of the semiconductor substrate on the surface of a semiconductor substrate to produce a laminated structure (laminated structure production step); irradiating the laminated structure with a laser having a wavelength range that penetrates the epitaxial layer but does not penetrate the semiconductor substrate from above the epitaxial layer to form a peeling layer near the interface between the semiconductor substrate and the epitaxial layer (peeling layer formation step); and separating the semiconductor substrate and the epitaxial layer at the peeling layer, wherein the focal position of the laser is within ±45 μm from the interface in the depth direction of the laminated structure, thereby enabling stable peeling of the epitaxial growth layer from the epitaxial growth substrate, reducing damage to the growth substrate, and increasing the number of times the growth substrate can be repeatedly used, thus completing the present invention.

[0031] [Substrate removal method] The substrate peeling method of the present invention will be described below with reference to the drawings. The epitaxial layer can be peeled off by an embodiment of the substrate peeling method of the present invention according to the process flow shown in Figure 1.

[0032] As shown in Figure 1, the substrate peeling method of the present invention includes a laminated structure fabrication step (S1), a peeling layer formation step (S2), and a separation step (S3). Furthermore, a step of placing a support substrate that holds the epitaxial layer on the epitaxial layer (support substrate placement step: S11) may be included before the separation step (S3), and an epitaxial layer processing step (S31) and a semiconductor substrate reprocessing step (S32) may be included after the separation step (S3). The following describes each step in detail with reference to the schematic diagram of the laminated structure 10 according to the present invention shown in Figure 2.

[0033] (Laminated structure fabrication process: S1) First, a laminated structure 1 is fabricated by forming an epitaxial layer 3 on the surface of the semiconductor substrate 2, having a band gap larger than the band gap of the semiconductor substrate 2.

[0034] In the present invention, a Si single crystal substrate can be used as the semiconductor substrate 2 for epitaxial growth. Si single crystal substrates are inexpensive and advantageous for increasing the diameter of epitaxial wafers, making them suitable for use as growth substrates in the present invention.

[0035] Furthermore, the epitaxial layer 3 may contain one or more of the following: GaN, AlGaN, AlN, Ga2O3, and SiC. This makes it possible to create a semiconductor device substrate with better suitability for high-frequency and high-power operation.

[0036] Epitaxial growth methods include MOCVD, HVPE, sputtering, PLD, mist CVD, reduced-pressure CVD, and ALD. However, the growth method is not particularly limited and can be applied to epitaxial layer 3 grown by any method, and different growth methods can be combined.

[0037] (Support board placement process: S11) Prior to the separation step (S3), the process may include a step of placing a support substrate 4 on the epitaxial layer 3 to hold the epitaxial layer 3. The support substrate 4 can be bonded to the epitaxial layer 3 via an adhesive layer 5 using an adhesive or the like.

[0038] By placing a support substrate 4 that holds the epitaxial layer 3 before peeling off the epitaxial layer 3, the epitaxial layer 3 can be made stable after peeling.

[0039] As will be described in detail later, in a later step, laser light is irradiated onto the laminated structure 1(10) to form a release layer. Therefore, to allow the laser to pass through the support substrate 4 and the adhesive layer 5, it is preferable to use a material such as glass for the support substrate 4 that holds the epitaxial layer 3, which has high light transmittance of wavelengths between 370 nm and 980 nm. For the adhesive layer 5, it is preferable to use an adhesive layer 5 that is transparent and has a refractive index close to that of the glass substrate. Epoxy, acrylate, polyimide, silicone, benzocyclobutene, etc., can be used.

[0040] (Peeling layer formation process: S2) Next, the laminated structure 1(10) is irradiated from above the epitaxial layer 3 with a laser in a wavelength range that penetrates the epitaxial layer 3 but not the semiconductor substrate 2. At this time, the focal position of the laser is set to a position within ±45 μm in the depth direction of the laminated structure 1(10) from the interface between the semiconductor substrate 2 and the epitaxial layer 3. Since the laser energy is absorbed by the semiconductor substrate 2, a delamination layer is formed near the interface, more specifically, within 1 nm from the interface toward the semiconductor substrate 2, in the depth direction (towards the interior of the semiconductor substrate 2). Figure 4 shows an explanatory diagram of the formation of the delamination layer by laser irradiation.

[0041] In this embodiment, a laser 6 is focused into the laminated structure 1(10) using a focusing lens, and by moving the focusing lens and the stage supporting the laminated structure 1(10) relatively, the laser is irradiated into the interior of the entire main surface of the laminated structure 1(10), thereby forming a release layer 7 inside the laminated structure 1(10).

[0042] Even if the laser's focal point is outside this range, the delamination layer can still be formed as long as the substrate is one that absorbs the laser. However, as will be discussed later, this can result in increased damage or a state insufficient for proper delamination, essentially degrading the quality of the delamination layer.

[0043] One method of laser irradiation by relatively moving the focusing lens and the laminated structure 1(10) is to place the laminated structure 1(10) on an XY stage, hold it with a vacuum chuck or electrostatic chuck, and move the laminated structure 1(10) in the X or Y direction on the XY stage, thereby moving the laminated structure 1(10) in a parallel direction to the focusing lens. This allows for continuous processing in the linear directions of the X and Y directions.

[0044] Alternatively, the laminated structure 1(10) can be placed on the stage of a device with a rotational drive, held in place by a vacuum chuck or electrostatic chuck, and the laminated structure 1(10) can be rotated while the focusing lens is moved in parallel to it, thereby enabling continuous processing in a spiral pattern.

[0045] In addition to the relative movement of the focusing lens and the laminated structure 1(10), the laser may also be scanned using laser beam changing means such as a galvanometer mirror or a polygon mirror. Furthermore, it is possible to split and irradiate the laser by combining the focusing lens with a diffractive optical element (DOE).

[0046] A numerical aperture (NA) of 0.85 or less in the focusing lens allows for better delamination, and more preferably 0.45 or less further reduces damage to the semiconductor substrate 2. Because the beam waist widens, the effects of thickness and waviness within the plane of the laminated structure 1(10) can be mitigated, further improving processing stability.

[0047] Spectrophotometer measurements of the transmittance of Si, GaN, and SiC at various wavelengths confirmed that Si transmits almost no light up to a wavelength of 980 nm, while GaN and SiC transmit light above a wavelength of 370 nm (see Figure 3). Therefore, lasers with wavelengths between 370 nm and 980 nm do not transmit light through Si, but they do transmit light through GaN and SiC.

[0048] When the semiconductor substrate 2 is a Si single crystal substrate and the epitaxial layer 3 is a GaN layer or a SiC layer, irradiating the epitaxial layer 3 with a laser of wavelength 370 to 980 nm from the epitaxial layer 3 side allows the laser to pass through the epitaxial layer 3 and be absorbed by the semiconductor substrate (Si substrate) 2, forming a delamination layer on the semiconductor substrate (Si substrate) 2 side, thereby allowing the epitaxial layer 3 to be peeled off.

[0049] Since GaN, AlGaN, AlN, and Ga2O3 have similar transmittances, even if the epitaxial layer 3 contains any of AlGaN, AlN, or Ga2O3, a delamination layer can be formed in the same manner as described above at a laser wavelength of 370 nm to 980 nm. Therefore, it is preferable to irradiate the laminated structure 1(10) with a laser wavelength of 370 nm to 980 nm.

[0050] If the material of the epitaxial layer 3 has transmittance characteristics that include a wavelength range (valley) within the aforementioned wavelength range where transmittance drops significantly, it is preferable to avoid wavelengths in the valley region. For example, in the case of SiC, it is preferable to exclude the range from 430 nm to 490 nm, where the transmittance is 10% or less, as the laser wavelength, and select a range of 370 nm or more and less than 430 nm, or greater than 490 nm and less than or equal to 980 nm.

[0051] For example, a pulsed laser with a pulse width of 1 μs or less can be used as the laser light source.

[0052] The laser is focused inside the laminated structure 1(10), primarily near the interface between the semiconductor substrate 2 and the epitaxial layer 3. Specifically, the laser's focal point is within ±45 μm of the depth of the laminated structure 1(10) from the interface (45 μm or less towards the epitaxial layer 3 from the interface, or 45 μm or less towards the semiconductor substrate 2 from the interface).

[0053] This allows for stable peeling of the epitaxial layer 3 from the semiconductor substrate 2, reducing damage to the semiconductor substrate 2 and increasing the number of times the semiconductor substrate 2 can be reused.

[0054] The laser focal position is preferably located within a range of ±15 to 45 μm (+15 to +45 μm or -15 to -45 μm) in the depth direction of the laminated structure 1 (10) from the interface. This makes it possible to further reduce damage to the semiconductor substrate 2 and increase the number of times the semiconductor substrate 2 can be reused.

[0055] (Separation process: S3) Next, the semiconductor substrate 2 and the epitaxial layer 3 are separated at the release layer 7. Specifically, the semiconductor substrate 2 and the epitaxial layer 3 can be separated by peeling them off, for example, by applying an external force to the release layer 7 of the laminated structure 1(10) on which the release layer 7 has been formed by laser irradiation.

[0056] One example of a method for applying external force to the delamination layer 7 is delamination by tensile testing. This can be achieved by fixing the semiconductor substrate 2 and the epitaxial layer 3 to a jig for tensile testing with an adhesive or the like and applying tensile stress.

[0057] In addition, the semiconductor substrate 2 and the epitaxial layer 3 can be separated by applying external force to the vicinity of the delamination layer 7 using a wedge such as a metal blade.

[0058] Furthermore, delamination can also be achieved by using an ultrasonic device that generates ultrasonic vibrations. By placing a laminated structure 1(10) with a delamination layer 7 on an ultrasonic device submerged in water and applying an external force by ultrasonic vibrations, the semiconductor substrate 2 and the epitaxial layer 3 can be separated.

[0059] (Epitaxial layer processing process: S31) The epitaxial layer 3 separated in the separation process (S3) can be directly bonded to the bonding substrate by performing a planarization process on the peeled surface. Figure 5 shows a schematic diagram of an example of a structure including the epitaxial layer 3 after peeling and planarization ((a) structure, (b) structure bonded to the bonding substrate).

[0060] Surface planarization can be performed by chemical processes such as dry etching, wet etching, or chemical mechanical polishing. For the bonding substrate 8, a high heat dissipation material such as a diamond substrate can be used from a thermal management perspective. Direct bonding can be performed, for example, by a surface activation bonding method using Ar ion beam or Ar fast atomic beam irradiation.

[0061] (Semiconductor substrate recycling process: S32) The semiconductor substrate 2 separated by the separation process (S3) can be reused repeatedly until the remaining thickness reaches a predetermined thickness by performing a regeneration process on the peeled surface. Figure 6 shows a schematic diagram of the semiconductor substrate 2 after peeling ((a) after peeling, (b) after regeneration process).

[0062] The reprocessing of the semiconductor substrate 2 is performed by removing the delamination layer (damaged layer) 7 remaining on the semiconductor substrate 2 after delamination. This can be done, for example, by chemical mechanical polishing.

[0063] [Method for manufacturing an epitaxial layer-containing structure] The present invention also provides a method for manufacturing an epitaxial layer-containing structure, which involves peeling the semiconductor substrate 2 from a laminated structure 1(10) having a semiconductor substrate 2 and an epitaxial layer 3 using the substrate peeling method described above, thereby producing a structure including the epitaxial layer 3.

[0064] This method for manufacturing an epitaxial layer-containing structure makes it possible to increase the number of times the semiconductor substrate 2 can be repeatedly used, while also producing an epitaxial layer-containing structure that is highly suitable for high-frequency and high-power operation. [Examples]

[0065] The present invention will be described in detail below with reference to examples, but this is not intended to limit the present invention.

[0066] (Example 1) A semiconductor substrate was prepared by heteroepitaxially growing a GaN epitaxial layer on a Si substrate using the MOCVD method. For support, the epitaxial layer was bonded to a glass substrate using an adhesive. Benzocyclobutene was used as the adhesive.

[0067] In Example 1, a focusing lens with a numerical aperture (NA) of 0.85 was used to irradiate the epitaxial layer from the side with a laser light source of wavelength 532 nm, a pulse width of 7 ns, and an oscillation frequency of 20 kHz, thereby forming a delamination layer. The laser focal positions were set at 0 μm, ±8 μm, ±15 μm, and ±45 μm in the depth direction of the semiconductor substrate from the interface between the Si substrate and the GaN epitaxial layer.

[0068] For the relative movement between the focusing lens and the semiconductor substrate, an XY stage was used to move the semiconductor substrate in the X and Y directions, thereby performing full-surface processing.

[0069] The Si substrate was peeled off from the semiconductor substrate on which the delamination layer had formed by tensile testing. To reuse the peeled Si substrate, it was subjected to chemical mechanical polishing.

[0070] The above stripping and polishing processes were performed three times for each focal point.

[0071] As a result, the required amount of Si substrate removal (removal allowance) for reuse was 5-7 μm at focal positions of 0 μm and ±8 μm, and 4-7 μm at focal positions of ±15 μm and ±45 μm.

[0072] (Example 2) Stripping and polishing were performed under the same conditions as in Example 1, except that a focusing lens with a numerical aperture (NA) of 0.45 was used.

[0073] As a result, the required amount of Si substrate removal (removal allowance) for reuse was 4-6 μm at focal positions of 0 μm and ±8 μm, and 2-4 μm at focal positions of ±15 μm and ±45 μm. By using a focusing lens with an NA of 0.45, damage to the Si substrate was further reduced compared to Example 1, and the amount of material removal required for reusing the Si substrate was further reduced.

[0074] (Comparative Example 1) Exfoliation and polishing were performed under the same conditions as in Example 1, except that the laser focal position was set to a position ±50 μm in the depth direction of the semiconductor substrate from the interface between the Si substrate and the GaN epitaxial layer.

[0075] As a result, the required amount of Si substrate removal (removal allowance) for reuse increased to 6-15 μm compared to Example 1, and in 2 out of 6 attempts, a good peel layer could not be formed and peeling was not possible.

[0076] (Comparative Example 2) Except for using a focusing lens with a numerical aperture (NA) of 0.45, the stripping and polishing were performed under the same conditions as in Comparative Example 1. As a result, the required amount of Si substrate removal (removal allowance) for reuse increased to 5-12 μm compared to Example 2, and in 2 out of 6 attempts, a good peel layer could not be formed and peeling was not possible.

[0077] (Comparative Example 3) Exfoliation was performed under the same conditions as in Example 1, except that the laser focal point was set to a position ±55 μm in the depth direction of the semiconductor substrate from the interface between the Si substrate and the GaN epitaxial layer. However, in all six attempts, a good exfoliated layer could not be formed, and exfoliation was unsuccessful. This is thought to be because the focal point position was too far from the interface between the Si substrate and the GaN epitaxial layer, making it difficult to adjust the laser irradiation conditions necessary to form a good exfoliated layer.

[0078] As described above, according to the embodiments of the present invention, it was possible to perform peeling in a more stable manner and with less damage to the growth substrate compared to Comparative Examples 1 to 3. This makes it possible to increase the number of times the growth substrate can be reused.

[0079] Regardless of the above examples and comparative examples, the laser output and irradiation interval can be adjusted as appropriate for the composition of each material and the experimental conditions.

[0080] This specification includes the following embodiments: [1] A substrate peeling method comprising the steps of: forming an epitaxial layer having a band gap larger than the band gap of the semiconductor substrate on the surface of a semiconductor substrate to produce a laminated structure; irradiating the laminated structure from above the epitaxial layer with a laser having a wavelength range that penetrates the epitaxial layer but does not penetrate the semiconductor substrate to form a peeling layer near the interface between the semiconductor substrate and the epitaxial layer; and separating the semiconductor substrate and the epitaxial layer at the peeling layer, wherein the focal position of the laser is within ±45 μm of the depth direction of the laminated structure from the interface. [2] The substrate peeling method of [1], comprising setting the focal position of the laser to a position within ±15 to 45 μm in the depth direction of the laminated structure from the interface. [3]: A substrate peeling method according to [1] or [2] above, further comprising the step of placing a support substrate for holding the epitaxial layer on the epitaxial layer before the separation step. [4]: The substrate peeling method according to [1], [2], or [3], further comprising using a Si single crystal substrate as the semiconductor substrate. [5]: The substrate peeling method according to [1], [2], [3], or [4], wherein the epitaxial layer comprises one or more of GaN, AlGaN, AlN, Ga2O3, and SiC. [6]: The substrate peeling method according to [4] or [5] above, comprising irradiating the laminated structure with the wavelength of the laser set to 370 nm or more and 980 nm or less. [7]: A method for manufacturing an epitaxial layer-containing structure, comprising peeling the semiconductor substrate from a laminated structure having the semiconductor substrate and the epitaxial layer by the substrate peeling method described in [1], [2], [3], [4], [5] or [6] above, thereby manufacturing a structure including the epitaxial layer.

[0081] It should be noted that the present invention is not limited to the embodiments described above. The embodiments described above are illustrative, and any configuration that is substantially identical to the technical idea described in the claims of the present invention and achieves similar effects is included within the technical scope of the present invention. [Explanation of Symbols]

[0082] 1, 10…Laminated structure, 2…Semiconductor substrate, 3…Epitaxial layer 4...Support substrate, 5...Adhesive layer, 6...Laser, 7...Release layer, 8...Bonding substrate.

Claims

1. A process of fabricating a laminated structure by forming an epitaxial layer having a band gap larger than the band gap of the semiconductor substrate on the surface of the semiconductor substrate, The laminated structure is irradiated from above the epitaxial layer with a laser having a wavelength range that penetrates the epitaxial layer but not the semiconductor substrate, thereby forming a delamination layer near the interface between the semiconductor substrate and the epitaxial layer. A substrate peeling method comprising a separation step of separating the semiconductor substrate and the epitaxial layer in the peeling layer, A method for peeling a substrate, characterized in that the focal position of the laser is within a range of ±45 μm from the interface in the depth direction of the laminated structure.

2. The substrate peeling method according to claim 1, characterized in that the focal position of the laser is within a range of ±15 to 45 μm in the depth direction of the laminated structure from the interface.

3. The substrate peeling method according to claim 1, characterized in that it includes a step of placing a support substrate for holding the epitaxial layer on the epitaxial layer prior to the separation step.

4. The substrate peeling method according to claim 1, characterized in that a Si single crystal substrate is used as the semiconductor substrate.

5. The epitaxial layer is made of GaN, AlGaN, AlN, Ga ２ O ３ The substrate peeling method according to claim 1, characterized in that it includes one or more of the following: and SiC.

6. The substrate peeling method according to claim 4, characterized in that the wavelength of the laser is set to 370 nm or more and 980 nm or less and irradiates the laminated structure.

7. A method for manufacturing an epitaxial layer-containing structure, characterized by peeling the semiconductor substrate from a laminated structure having the semiconductor substrate and the epitaxial layer using the substrate peeling method described in any one of claims 1 to 6, thereby manufacturing a structure including the epitaxial layer.

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