A method of manufacturing a semiconductor device

Abstract

The application relates to the technical field of semiconductor devices, in particular to a preparation method of a semiconductor element. The preparation method of the semiconductor element comprises the following steps: growing a first epitaxial layer on one side of a substrate layer; forming a first modified layer in the substrate layer by using laser; separating a first substrate with a preset thickness range from the substrate layer along the first modified layer; wherein the first epitaxial layer is located on the first substrate; and preparing a first device on the surface of the first epitaxial layer. In the application, laser is incident from any side of the substrate layer, the first modified layer is processed in the substrate layer by using the laser, and the first substrate with the preset thickness range is directly processed, and the thickness of the first substrate is usually 50-150 mu m. Therefore, the processing efficiency can be improved, and by grinding and polishing the stripping surface of the first substrate, the first substrate with the preset thickness range can be obtained by flattening the defect area after the laser action, and the waste of the material can be effectively reduced.

Description

Technical Field

[0001] This invention relates to the field of semiconductor device technology, and more specifically, to a method for fabricating a semiconductor element. Background Technology

[0002] Reducing the on-resistance of SiC and GaN devices (on-resistance is the ratio of voltage across a diode to its current after it conducts, and is a crucial parameter for diodes) can improve device performance. Typically, after the film structure of the device is fabricated, the SiC substrate needs to be thinned. However, this results in the waste of a large amount of SiC (e.g., approximately 200–300 μm) through grinding. Furthermore, due to the high hardness of SiC, traditional mechanical thinning methods have low rates of reduction, cause significant damage to the grinding head, and pose a high risk of substrate breakage. Consequently, the manufacturing cost and selling price of these devices remain high, severely limiting their widespread application in various fields. Summary of the Invention

[0003] The problem solved by this invention is that the utilization rate of substrate material is low and material waste is serious in traditional thinning processes.

[0004] To address the aforementioned problems, this invention provides a method for fabricating a semiconductor device. The method includes: growing a first epitaxial layer on one side of a substrate layer; forming a first modified layer within the substrate layer using a laser; separating a first substrate of a predetermined thickness range from the substrate layer along the first modified layer; wherein the first epitaxial layer is located on the first substrate; and fabricating a first device on the surface of the first epitaxial layer.

[0005] Optionally, before separating the substrate layer along the first modified layer, the method further includes: fixing the first release substrate to the surface of the first epitaxial layer and the substrate layer through a temporary bonding process.

[0006] Optionally, before fabricating the first device on the surface of the first epitaxial layer, the method further includes: separating the first stripped substrate from the first epitaxial layer by a debonding process.

[0007] Optionally, before fabricating the first device on the surface of the first epitaxial layer, the method further includes: polishing the release surface of the first substrate; and fixing the release surface of the first substrate onto the first support substrate through a temporary bonding process.

[0008] Optionally, after fabricating the first device on the surface of the first epitaxial layer, the method further includes: separating the first substrate from the first supporting substrate by a debonding process.

[0009] Optionally, the method for fabricating the semiconductor device further includes: growing a second epitaxial layer on the surface of the remaining substrate layer; forming a second modified layer in the remaining substrate layer using a laser; separating a second substrate of a predetermined thickness range from the remaining substrate layer along the second modified layer; wherein the second epitaxial layer is located on the second substrate; and fabricating a second device on the surface of the second epitaxial layer.

[0010] Optionally, before growing the second epitaxial layer on the remaining substrate surface, the method further includes polishing the remaining substrate surface.

[0011] Optionally, before separating the remaining substrate layer along the second modified layer, the method further includes: fixing the second release substrate to the surface of the second epitaxial layer and the remaining substrate layer by a temporary bonding process.

[0012] Optionally, before fabricating the second device on the surface of the second epitaxial layer, the method further includes: separating the second stripping substrate from the second epitaxial layer by a bonding release process.

[0013] Optionally, before fabricating the second device on the surface of the second epitaxial layer, the method further includes: polishing the release surface of the second substrate; and fixing the release surface of the second substrate onto the second support substrate through a temporary bonding process.

[0014] Optionally, after fabricating the second device on the surface of the second epitaxial layer, the method further includes: separating the second substrate from the second support substrate by a debonding process.

[0015] The beneficial effects of the semiconductor element fabrication method of the present invention are:

[0016] By incident a laser from either side of the substrate, the laser can process a first modified layer inside the substrate, directly producing a first substrate of a predetermined thickness, typically 50 μm to 150 μm. This improves processing efficiency, and by polishing the peeled surface of the first substrate, only the defective areas left by the laser action need to be smoothed out to obtain the first substrate of the predetermined thickness, effectively reducing excessive material waste.

[0017] The present invention provides a method for fabricating a semiconductor device, which further includes: growing a first epitaxial layer and a third epitaxial layer on opposite sides of a substrate layer; forming a first modified layer in the substrate layer using a laser; separating a first substrate and a third substrate of a predetermined thickness range along the first modified layer from the substrate layer; wherein the first epitaxial layer is disposed on the first substrate and the third epitaxial layer is disposed on the third substrate; fabricating a first device on the surface of the first epitaxial layer and fabricating a third device on the surface of the third epitaxial layer.

[0018] Optionally, before separating the substrate layer along the first modified layer, the method further includes: fixing the third release substrate onto the surfaces of the first epitaxial layer and the third epitaxial layer respectively through a temporary bonding process.

[0019] Optionally, before fabricating a first device on the surface of the first epitaxial layer and before fabricating a third device on the surface of the third epitaxial layer, the method further includes: separating the third release substrate from the first epitaxial layer and the third epitaxial layer respectively by a bonding release process.

[0020] Optionally, before fabricating a first device on the surface of the first epitaxial layer and a third device on the surface of the third epitaxial layer, the method further includes: polishing the release surfaces of the first substrate and the third substrate; fixing the release surface of the first substrate to the third support substrate and fixing the release surface of the third substrate to the fourth support substrate through a temporary bonding process.

[0021] Optionally, after fabricating a first device on the surface of the first epitaxial layer and fabricating a third device on the surface of the third epitaxial layer, the method further includes: separating the third supporting substrate from the first substrate and separating the fourth supporting substrate from the third substrate by a bonding release process.

[0022] The beneficial effects of the semiconductor element fabrication method of the present invention are:

[0023] By incident a laser from either side of the substrate layer, the laser processes a first modified layer within the substrate layer, directly producing a first substrate and a third substrate within a predetermined thickness range. This significantly improves processing efficiency, allowing both the first and third substrates to be processed simultaneously in a single laser operation, effectively doubling the efficiency. Furthermore, by polishing the stripped surfaces of the first and third substrates, only the defective areas left by the laser action need to be smoothed to obtain the first and third substrates within the predetermined thickness range, effectively reducing excessive material waste. This invention also provides a method for fabricating a semiconductor device that includes: forming a first modified layer within the substrate layer using a laser; separating a first substrate within a predetermined thickness range from the substrate layer along the first modified layer; growing a first epitaxial layer on the first substrate; and fabricating a first device on the surface of the first epitaxial layer.

[0024] Optionally, before separating the substrate layer along the first modified layer, the method further includes: fixing the fourth release substrate to opposite sides of the substrate layer through a temporary bonding process.

[0025] Optionally, before growing the first epitaxial layer on the first substrate, the method further includes: separating the fourth stripping substrate from the first substrate by a debonding process.

[0026] Optionally, after separating the substrate layer along the first modified layer, the process further includes: polishing the release surface of the first substrate; and fixing the release surface of the first substrate onto the fourth support substrate through a temporary bonding process.

[0027] Optionally, after fabricating the first device on the surface of the first epitaxial layer, the method further includes: separating the first substrate from the fourth support substrate by a debonding process.

[0028] The beneficial effects of the semiconductor element fabrication method of the present invention are:

[0029] By incident a laser from either side of the substrate, the laser can process a first modified layer inside the substrate, directly producing a first substrate of a predetermined thickness, typically 50 μm to 150 μm. This improves processing efficiency, and by polishing the peeled surface of the first substrate, only the defective areas left by the laser action need to be smoothed out to obtain the first substrate of the predetermined thickness, effectively reducing excessive material waste. Attached Figure Description

[0030] Figure 1 This is a schematic flowchart of a method for fabricating a semiconductor element according to an embodiment of the present invention;

[0031] Figure 2 This is a schematic diagram illustrating the detailed steps following step S110 in the semiconductor element fabrication method of this embodiment of the invention.

[0032] Figure 3 This is a schematic diagram illustrating the detailed steps following step S130 in the semiconductor element fabrication method of this embodiment of the invention.

[0033] Figure 4 This is a detailed schematic diagram of step S130 of the semiconductor element fabrication method according to an embodiment of the present invention;

[0034] Figure 5 This is a detailed schematic diagram of step S130 of the semiconductor element fabrication method according to an embodiment of the present invention;

[0035] Figure 6 This is a detailed schematic diagram of step S130 of the semiconductor element fabrication method according to an embodiment of the present invention;

[0036] Figure 7 This is a detailed schematic diagram of step S130 of the semiconductor element fabrication method according to an embodiment of the present invention;

[0037] Figure 8 This is a schematic diagram of the semiconductor device fabrication process according to an embodiment of the present invention;

[0038] Figure 9This is a schematic flowchart of a method for fabricating a semiconductor element according to an embodiment of the present invention;

[0039] Figure 10 This is a schematic diagram illustrating the detailed steps following step S101 in the preparation method of this embodiment of the invention;

[0040] Figure 11 This is a schematic diagram illustrating the detailed steps following step S103 in the semiconductor element fabrication method of this embodiment of the invention.

[0041] Figure 12 This is a schematic diagram of the semiconductor device fabrication process according to an embodiment of the present invention;

[0042] Figure 13 This is a schematic flowchart of a method for fabricating a semiconductor element according to an embodiment of the present invention;

[0043] Figure 14 This is a detailed schematic diagram of step S200 in the preparation method of this invention.

[0044] Figure 15 This is a schematic diagram illustrating the detailed steps following step S300 in the preparation method of this embodiment of the invention;

[0045] Figure 16 This is a schematic diagram of the semiconductor device fabrication process according to an embodiment of the present invention.

[0046] Explanation of reference numerals in the attached figures:

[0047] 1-Base layer; 2-Remaining base layer; 3-First epitaxial layer; 4-Second epitaxial layer; 5-Third epitaxial layer; 6-First stripped substrate; 7-Second stripped substrate; 8-Third stripped substrate; 9-Fourth stripped substrate; 10-First substrate; 11-Second substrate; 12-Third substrate; 13-First support substrate; 14-Second support substrate; 15-Third support substrate; 16-Fourth support substrate; 17-First device; 18-Second device; 19-Third device; 20-First modified layer; 21-Second modified layer. Detailed Implementation

[0048] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0049] It should be noted that the terms "first," "second," "third," and "fourth," etc., used in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in sequences other than those illustrated or described herein.

[0050] like Figure 1 , Figure 8 As shown, one embodiment of the present invention provides a method for fabricating a semiconductor device, the method comprising:

[0051] Step S110: A first epitaxial layer 3 is grown on one side of the base layer 1.

[0052] Specifically, the substrate 1 can be made of materials such as silicon carbide (SiC) and gallium nitride (GaN). These materials have superior physical properties such as wide bandgap, high critical breakdown field strength, and high thermal conductivity, making them widely used in aerospace, smart grids, rail transportation, new energy power generation, electric vehicles, and industrial power supplies.

[0053] Specifically, the first epitaxial layer 3 can be a homogeneous epitaxial layer, that is, the first epitaxial layer 3 and the substrate layer 1 are made of the same material; for example, the substrate layer 1 is made of silicon carbide (SiC) material, and the first epitaxial layer 3 is also made of silicon carbide (SiC) material; the first epitaxial layer 3 can also be a heterogeneous epitaxial layer, that is, the first epitaxial layer 3 and the substrate layer 1 are made of different materials; for example, the substrate layer 1 is made of silicon carbide (SiC) material, while the first epitaxial layer 3 is made of a different material than the substrate layer 1, such as one or more of gallium nitride (GaN), aluminum gallium nitride (AlGaN), aluminum nitride (AlN), etc.

[0054] like Figure 1 As shown, in step S120, a first modified layer 20 is formed in the substrate layer 1 using a laser.

[0055] Specifically, the first modified layer 20 is created by focusing a laser beam of a specific wavelength inside the wafer through a lens, generating a localized deformation layer inside the wafer. This layer mainly consists of voids, a high dislocation density layer, and cracks. The first modified layer 20 serves as the starting point for subsequent wafer dicing and cracking. By optimizing the laser and optical path system, the first modified layer 20 can be confined inside the wafer, preventing thermal damage to the wafer surface and bottom surface. Then, external force is used to guide the cracks to the wafer surface and bottom surface, thereby separating the wafer into the required size. The first modified layer 20 can be composed of a densely packed ablation lattice or a crack layer.

[0056] During the process of irradiating the interior of the substrate 1 with a laser, the photon energy of the laser used must be less than the bandgap of the substrate 1 material and the first epitaxial layer 3 material. For example, the photon energy of the laser on the substrate 1 material must be less than the bandgap of SiC (2–2.7 eV); the photon energy of the laser on the first epitaxial layer 3 material must be less than the bandgap of one or more of SiC, GaN (3.39 eV), AlGaN (3.4–6.2 eV), and AlN (6.42 eV). This allows the laser to penetrate the surface of the substrate 1 and be focused inside the substrate 1 to form the first modified layer 20.

[0057] like Figure 1 , Figure 2 As shown, before separating the substrate layer 1 along the first modified layer 20, the method for preparing the semiconductor device further includes: step S140, fixing the first release substrate 6 to the surface of the first epitaxial layer 3 and the substrate layer 1 through a temporary bonding process.

[0058] Specifically, external force can be applied to the first release substrate 6 to separate the base layer 1 from the first substrate 10 of a predetermined thickness along the first modified layer 20; wherein, the first release substrate 6 is located on the base layer 1 and the first epitaxial layer 3 respectively. The first release substrate 6 can be silicon carbide (SiC), sapphire, glass, metal, etc. The function of the first release substrate 6 is, on the one hand, to protect the base layer 1 from breakage in subsequent processes, and on the other hand, to serve as an auxiliary force during the subsequent release of the base layer 1, facilitating the application of external force to the first release substrate 6 to release the base layer 1.

[0059] Step S140 can be performed before step S120. When the distance between the first modified layer 20 and the first epitaxial layer 3 is small (e.g., 50-150 μm), the first substrate 10 and the first epitaxial layer 3 are prone to cracking due to stress in the first modified layer 20 during laser processing. In this case, step S140 can be performed first. Before laser processing, a first release substrate 6 made of a transparent material that can be penetrated by the laser, such as silicon carbide (SiC), sapphire, or glass, is required. The first release substrate 6 made of such material is bonded to the surface of the first epitaxial layer 3. The bonding process can increase the strength of the first epitaxial layer 3 and the substrate layer 1, thereby preventing the first epitaxial layer 3 and the substrate layer 1 from cracking under laser stress.

[0060] like Figure 1 As shown, in step S130, the base layer 1 is separated into a first substrate 10 with a predetermined thickness range along the first modified layer 20; wherein, the first epitaxial layer 3 is located on the first substrate 10.

[0061] Specifically, under normal processing conditions, a silicon carbide (SiC) layer with a thickness of 500 μm is typically chosen as the substrate layer 1 to ensure that bending or cracking does not occur during the subsequent fabrication of the first device 17 on the first epitaxial layer 3. After the first device 17 is fabricated, the substrate layer 1 needs to be ground to reduce the thickness of the semiconductor element from 500 μm to 50 μm to 150 μm. Due to the substrate layer 1 being made of materials such as silicon carbide (SiC), which has a Mohs hardness of 9.5, the grinding wheel needs to be made of relatively expensive diamond material, resulting in lower grinding efficiency and wheel lifespan. Furthermore, the grinding process also leads to significant waste of silicon carbide (SiC) material, increasing costs.

[0062] In this embodiment, by incident a laser from either side of the substrate layer 1, the laser processes a first modified layer 20 within the substrate layer 1, directly producing a first substrate 10 of a predetermined thickness range, typically 50 μm to 150 μm. This improves processing efficiency, and by polishing the peeled surface of the first substrate 10, only the defective areas after laser treatment need to be smoothed to obtain the first substrate 10 of the predetermined thickness range, effectively reducing excessive material waste.

[0063] like Figure 1 , Figure 3 As shown, before fabricating the first device 17 on the surface of the first epitaxial layer 3, the method for fabricating the semiconductor element further includes: step S150, polishing the release surface of the first substrate 10; and fixing the release surface of the first substrate 10 onto the first support substrate 13 through a temporary bonding process.

[0064] Specifically, polishing the release surface of the first substrate 10 removes defective areas caused by laser treatment and obtains a smooth surface, ensuring the quality of the subsequently fabricated semiconductor devices. After polishing the release surface of the first substrate 10, a temporary bonding process is used to fix the release surface of the first substrate 10 onto the first support substrate 13. The first support substrate 13 is used to support the first substrate 10 and the first epitaxial layer 3. Since the first substrate 10 and the first epitaxial layer 3 are relatively thin, the first support substrate 13 ensures that bending or cracking will not occur during the subsequent fabrication of the first device 17 on the first epitaxial layer 3.

[0065] like Figures 1 to 3 As shown, before fabricating the first device 17 on the surface of the first epitaxial layer 3, the method for fabricating the semiconductor element further includes: step S160, separating the first stripped substrate 6 from the first epitaxial layer 3 by a bonding release process.

[0066] Specifically, after the first release substrate 6 separates from the first epitaxial layer 3, the first epitaxial layer 3 is located on the first substrate 10, thereby allowing subsequent processes to be performed to fabricate the first device 17 on the first epitaxial layer 3. After the first release substrate 6 separates from the remaining base layer 2, the remaining base layer 2 can continue to undergo subsequent processing steps.

[0067] The order of steps S150 and S160 can be reversed; executing step S150 first or step S160 first will achieve the same effect.

[0068] like Figure 1 , Figure 3 As shown, in step S170, a first device 17 is fabricated on the surface of the first epitaxial layer 3. Specifically, the first device 17 can be a bipolar junction transistor (BJT), a metal-oxide-semiconductor field-effect transistor (MOSFET), or the like.

[0069] Following step S170, the method for fabricating the semiconductor element further includes step S180, in which the first substrate 10 is separated from the first supporting substrate 13 by a debonding process. This completes the fabrication of the semiconductor element.

[0070] like Figure 4 , Figure 5 As shown, in another embodiment of the present invention, according to step S130, the method for preparing the semiconductor element further includes:

[0071] Step S132: Grow a second epitaxial layer 4 on the surface of the remaining base layer 2.

[0072] Before step S132, the process also includes step S131, which involves polishing the remaining surface of the substrate layer 2. In the preceding step S130, defective areas may remain on the surface of the remaining substrate layer 2 after laser treatment. Step S131 polishes the remaining surface of the substrate layer 2 to remove these defective areas and obtain a smooth surface, ensuring the quality of the subsequently fabricated semiconductor devices.

[0073] After the surface of the remaining substrate layer 2 is polished smooth, a second epitaxial layer 4 is grown on the surface of the remaining substrate layer 2. The second epitaxial layer 4 can be a homoepitaxial layer, that is, the second epitaxial layer 4 uses the same material as the substrate layer 1; for example, the substrate layer 1 uses silicon carbide (SiC) material, and the second epitaxial layer 4 also uses silicon carbide (SiC) material; the second epitaxial layer 4 can also be a heteroepitaxial layer, that is, the second epitaxial layer 4 uses a different material than the substrate layer 1; for example, the substrate layer 1 uses silicon carbide (SiC) material, while the second epitaxial layer 4 uses a different material than the substrate layer 1, such as one or more of gallium nitride (GaN), aluminum gallium nitride (AlGaN), aluminum nitride (AlN), etc.

[0074] like Figure 4 , Figure 5 As shown, in step S133, a second modified layer 21 is formed within the remaining substrate layer 2 using a laser. Step S133 can be performed before step S132.

[0075] Specifically, the second modified layer 21 is created by focusing a laser beam of a specific wavelength inside the wafer through a lens, generating a localized deformation layer inside the wafer. This layer mainly consists of voids, a high dislocation density layer, and cracks. The second modified layer 21 serves as the starting point for subsequent wafer dicing and cracking. By optimizing the laser and optical path system, the second modified layer 21 can be confined inside the wafer, preventing thermal damage to the wafer surface and bottom surface. External force is then used to guide the cracks to the wafer surface and bottom surface, thereby separating the wafer to the required size. The second modified layer 21 can be composed of a densely packed ablation lattice or a crack layer.

[0076] During the process of irradiating the interior of the remaining substrate layer 2 with a laser, the photon energy of the laser used must be less than the bandgap of the remaining substrate layer 2 material and the second epitaxial layer 4 material. For example, the photon energy of the laser in the remaining substrate layer 2 material must be less than the bandgap of SiC (2–2.7 eV); the photon energy of the laser in the second epitaxial layer 4 material must be less than the bandgap of one or more of SiC, GaN (3.39 eV), AlGaN (3.4–6.2 eV), and AlN (6.42 eV). This allows the laser to penetrate the surface of the substrate layer 1 and be focused inside the substrate layer 1 to form the second modified layer 21.

[0077] like Figure 4 , Figure 7 As shown, in step S135, the remaining base layer 2 is separated along the second modified layer 21 to form a third base layer 1 and a second substrate 11 with a preset thickness range; wherein, the second epitaxial layer 4 is located on the second substrate 11.

[0078] Specifically, under normal processing conditions, a silicon carbide (SiC) layer with a thickness of 500 μm is typically chosen as the substrate layer 1 to prevent bending or cracking during the subsequent fabrication of the second device 18 on the second epitaxial layer 4. After the second device 18 is fabricated, the substrate layer 1 needs to be ground to reduce the thickness of the semiconductor element from 500 μm to 50 μm–150 μm. Because the substrate layer 1 is made of materials such as silicon carbide (SiC), which has a Mohs hardness of 9.5, the grinding wheel needs to be made of relatively expensive diamond material, resulting in lower grinding efficiency and wheel lifespan. Furthermore, the grinding process also leads to significant waste of silicon carbide (SiC) material, increasing costs.

[0079] In this embodiment, by incident a laser from either side of the substrate layer 1, the laser processes a second modified layer 21 within the substrate layer 1, directly producing a second substrate 11 of a predetermined thickness range, typically 50 μm to 150 μm. This improves processing efficiency, and by polishing the peeled surface of the second substrate 11, only the defective areas after laser treatment need to be smoothed to obtain the second substrate 11 of the predetermined thickness range, effectively reducing excessive material waste.

[0080] like Figures 4 to 6 As shown, before separating the remaining substrate layer 2 along the second modified layer 21, the method for preparing the semiconductor device further includes: step S134, fixing the second stripping substrate 7 to the surface of the second epitaxial layer 4 and the remaining substrate layer 2 through a temporary bonding process.

[0081] Specifically, external force can be applied to the second release substrate 7 to separate the remaining base layer 2 along the second modified layer 21 to form a second substrate 11 of a predetermined thickness range. The second release substrate 7 is located on both the remaining base layer 2 and the second epitaxial layer 4. The second release substrate 7 can be made of silicon carbide (SiC), sapphire, glass, metal, etc. The function of the second release substrate 7 is twofold: firstly, to protect the remaining base layer 2 from breakage in subsequent processes; and secondly, to assist in the subsequent peeling of the remaining base layer 2, facilitating the application of external force to the second release substrate 7 for peeling.

[0082] Step S134 can be performed before step S133. When the distance between the second modified layer 21 and the second epitaxial layer 4 is small (e.g., 50-150 μm), the second substrate 11 and the second epitaxial layer 4 are prone to cracking due to stress in the second modified layer 21 during laser processing. In this case, step S134 can be performed first. Before laser processing, a second release substrate 7 made of a transparent material that can be penetrated by the laser, such as silicon carbide (SiC), sapphire, or glass, is required. The second release substrate 7 made of such material is bonded to the surface of the second epitaxial layer 4. The bonding process can increase the strength of the second epitaxial layer 4 and the second substrate 11, thereby preventing the second substrate 11 from cracking under laser stress.

[0083] like Figure 4 , Figure 7 As shown, before fabricating the second device 18 on the surface of the second epitaxial layer 4, the method for fabricating the semiconductor element further includes: step S136, polishing the release surface of the second substrate 11; and fixing the release surface of the second substrate 11 onto the second support substrate 14 through a temporary bonding process.

[0084] Specifically, polishing the release surface of the second substrate 11 removes defective areas caused by laser treatment and obtains a smooth surface, ensuring the quality of the subsequently fabricated semiconductor devices. After polishing the release surface of the second substrate 11, a temporary bonding process is used to fix the release surface of the second substrate 11 onto the second support substrate 14. The second support substrate 14 is used to support the second substrate 11 and the second epitaxial layer 4. Since the second substrate 11 and the second epitaxial layer 4 are relatively thin, the second support substrate 14 ensures that bending or cracking will not occur during the subsequent fabrication of the second device 18 on the second epitaxial layer 4.

[0085] like Figure 4 , Figure 6 As shown, before fabricating the second device 18 on the surface of the second epitaxial layer 4, the method for fabricating the semiconductor element further includes: step S137, separating the second stripping substrate 7 from the second epitaxial layer 4 by a bonding release process.

[0086] Specifically, after the second release substrate 7 separates from the second epitaxial layer 4, the second epitaxial layer 4 is located on the second substrate 11, allowing subsequent processes to be performed to fabricate the second device 18 on the second epitaxial layer 4. After the second release substrate 7 separates from the remaining base layer 2, the remaining base layer 2 can continue to undergo subsequent processing steps. The order of steps S136 and S137 can be interchanged; performing step S136 first or step S137 first achieves the same effect.

[0087] like Figure 4 , Figure 7 As shown, in step S138, a second device 18 layer is fabricated on the surface of the second epitaxial layer 4. The second device 18 can be a bipolar junction transistor (BJT), a metal-oxide-semiconductor field-effect transistor (MOSFET), or the like.

[0088] After fabricating the second device 18 on the surface of the first epitaxial layer 3, the method for fabricating the semiconductor element further includes: step S139, separating the second substrate 11 from the second support substrate 14 by a debonding process. This completes the fabrication of the semiconductor element. For a thicker substrate layer 1, several semiconductor elements can be fabricated using the above steps.

[0089] like Figure 9 , Figure 12 As shown, in another embodiment of the present invention, the method for preparing the semiconductor element further includes:

[0090] In step S101, a first epitaxial layer 3 and a third epitaxial layer 5 are grown on opposite sides of the substrate layer 1.

[0091] Specifically, the first epitaxial layer 3 and the third epitaxial layer 5 can be homogeneous epitaxial layers, meaning that the first epitaxial layer 3 and the third epitaxial layer 5 are made of the same material as the substrate layer 1; for example, if the substrate layer 1 is made of silicon carbide (SiC), the first epitaxial layer 3 and the third epitaxial layer 5 are also made of silicon carbide (SiC). Alternatively, the first epitaxial layer 3 and the third epitaxial layer 5 can be heterogeneous epitaxial layers, meaning that the first epitaxial layer 3 and the third epitaxial layer 5 are made of a different material than the substrate layer 1; for example, if the substrate layer 1 is made of silicon carbide (SiC), the first epitaxial layer 3 and the third epitaxial layer 5 are made of a different material than the substrate layer 1, such as one or more of gallium nitride (GaN), aluminum gallium nitride (AlGaN), and aluminum nitride (AlN). Furthermore, the first epitaxial layer 3 and the third epitaxial layer 5 can also be made of different materials.

[0092] like Figure 9 As shown, in step S102, the first modified layer 20 is formed in the substrate layer 1 using a laser.

[0093] Specifically, the first modified layer 20 is created by focusing a laser beam of a specific wavelength inside the wafer through a lens, generating a localized deformation layer inside the wafer. This layer mainly consists of voids, a high dislocation density layer, and cracks. The modified layer serves as the starting point for subsequent wafer dicing and cracking. By optimizing the laser and optical path system, the modified layer can be confined inside the wafer, preventing thermal damage to the wafer surface and bottom surface. Then, external force is used to guide the cracks to the wafer surface and bottom surface, thereby separating the wafer into the required dimensions. The first modified layer 20 can be composed of a densely packed ablation lattice or a crack layer.

[0094] During the process of irradiating the interior of the substrate 1 with a laser, the photon energy of the laser used must be less than the bandgap of the substrate 1 material and the first epitaxial layer 3 material. For example, the photon energy of the laser on the substrate 1 material must be less than the bandgap of SiC (2–2.7 eV); the photon energy of the laser on the first epitaxial layer 3 material must be less than the bandgap of one or more of SiC, GaN (3.39 eV), AlGaN (3.4–6.2 eV), and AlN (6.42 eV). This allows the laser to penetrate the surface of the substrate 1 and be focused inside the substrate 1 to form the first modified layer 20.

[0095] like Figure 9 , Figure 10 As shown, before separating the substrate layer 1 along the first modified layer 20, the method for preparing the semiconductor device further includes: step S104, fixing the third release substrate 8 to the surface of the first epitaxial layer 3 and the third epitaxial layer 5 through a temporary bonding process.

[0096] Specifically, external force can be applied to the third release substrate 8 to separate the base layer 1 along the first modified layer 20 into a first substrate 10 and a third substrate 12 with a predetermined thickness range; wherein, the third release substrate 8 is located on the first epitaxial layer 3 and the third epitaxial layer 5, respectively. The third release substrate 8 can be silicon carbide (SiC), sapphire, glass, metal, etc. The function of the third release substrate 8 is, on the one hand, to protect the base layer 1 from breakage in subsequent processes; on the other hand, it serves as an auxiliary force during the subsequent release of the base layer 1, facilitating the application of external force to the third release substrate 8 to release the base layer 1.

[0097] Step S104 can be performed before step S102. When the distance between the first modified layer 20 and the first epitaxial layer 3 and / or the third epitaxial layer 5 is small (e.g., 50-150 μm), the first substrate 10, first epitaxial layer 3, third substrate 12, and third epitaxial layer 5 are prone to cracking due to stress in the first modified layer 20 during laser processing. In this case, step S104 can be performed first. Before laser processing, a third release substrate 8 made of a transparent material that can be penetrated by the laser is required, such as silicon carbide (SiC), sapphire, or glass. The third release substrate 8 made of such material is bonded to the surfaces of the first epitaxial layer 3 and the third epitaxial layer 5. The bonding process can increase the strength of the first substrate 10, first epitaxial layer 3, third substrate 12, and third epitaxial layer 5, thereby preventing cracking of the first substrate 10, first epitaxial layer 3, third substrate 12, and third epitaxial layer 5 under laser stress.

[0098] like Figure 9 As shown, in step S103, the first substrate 10 and the third substrate 12 with a preset thickness range are separated from the first modified layer 20 along the base layer 1; wherein, the first epitaxial layer 3 is disposed on the first substrate 10, and the third epitaxial layer 5 is disposed on the third substrate 12.

[0099] In this embodiment, by incident a laser from either side of the substrate 1, the laser processes a first modified layer 20 within the substrate 1, directly producing a first substrate 10 and a third substrate 12 within a predetermined thickness range. This improves processing efficiency, allowing both the first substrate 10 and the third substrate 12 to be processed simultaneously in a single laser operation, effectively doubling the efficiency. Furthermore, by polishing the peeled surfaces of the first substrate 10 and the third substrate 12, only the defective areas left by the laser action need to be smoothed to obtain the first substrate 10 and the third substrate 12 within the predetermined thickness range, effectively reducing excessive material waste.

[0100] like Figure 9 , Figure 11As shown, a first device 17 is fabricated on the surface of the first epitaxial layer 3, and a third device 19 is fabricated on the surface of the third epitaxial layer 5. The method for fabricating the semiconductor device further includes: step S107, polishing the release surfaces of the first substrate 10 and the third substrate 12; fixing the release surface of the first substrate 10 to the third support substrate 15 through a temporary bonding process, and fixing the release surface of the third substrate 12 to the third support substrate 15.

[0101] Specifically, polishing the release surfaces of the first substrate 10 and the third substrate 12 removes defective areas caused by laser treatment and obtains a smooth surface, ensuring the quality of subsequently fabricated semiconductor devices. After polishing the release surfaces of the first substrate 10 and the third substrate 12, a temporary bonding process is used to fix the release surfaces of the first substrate 10 and the third substrate 12 onto the third support substrate 15. The first substrate 10 and the third substrate 12 can be fixed to the same third support substrate 15, or they can be fixed to different third support substrates 15.

[0102] The third support substrate 15 is used to support the first substrate 10 and the first epitaxial layer 3. The third support substrate 15 is also used to support the third substrate 12 and the third epitaxial layer 5. Since the first substrate 10, the first epitaxial layer 3, the third substrate 12 and the third epitaxial layer 5 are relatively thin, the third support substrate 15 can ensure that bending or cracking will not occur during the subsequent fabrication of the first device 17 on the first epitaxial layer 3 and the third device 19 on the third epitaxial layer 5.

[0103] like Figures 9 to 11 As shown, a first device 17 is fabricated on the surface of the first epitaxial layer 3, and a third device 19 is fabricated on the surface of the third epitaxial layer 5. The method for fabricating the semiconductor device further includes step S106, in which the third stripping substrate 8 is separated from the first epitaxial layer 3 and the third epitaxial layer 5 respectively by a bonding release process.

[0104] Specifically, after the third release substrate 8 is separated from the first epitaxial layer 3 and the third epitaxial layer 5, the first epitaxial layer 3 is located on the first substrate 10, and the third epitaxial layer 5 is located on the third substrate 12. This allows subsequent processes to proceed, including fabricating the first device 17 on the first epitaxial layer 3 and the third device 19 on the third epitaxial layer 5.

[0105] The order of steps S105 and S106 can be reversed; executing step S105 first or step S106 first will achieve the same effect.

[0106] like Figure 9 , Figure 11As shown, in step S107, a first device 17 is fabricated on the surface of the first epitaxial layer 3, and a third device 19 is fabricated on the surface of the third epitaxial layer 5. Specifically, the first device 17 and the third device 19 can be bipolar junction transistors (BJTs), metal-oxide-semiconductor field-effect transistors (MOSFETs), etc.

[0107] Following step S107, the method for fabricating the semiconductor element further includes step S108, in which the first substrate 10 and the third substrate 12 are separated from the third supporting substrate 15 by a bonding release process. This completes the fabrication of the semiconductor element.

[0108] like Figure 13 , Figure 16 As shown, in another embodiment of the present invention, the method for fabricating the semiconductor element further includes:

[0109] Step S200: A first modified layer 20 is formed in the substrate layer 1 using a laser;

[0110] Specifically, the first modified layer 20 is created by focusing a laser beam of a specific wavelength inside the wafer through a lens, generating a localized deformation layer inside the wafer. This layer mainly consists of voids, a high dislocation density layer, and cracks. The first modified layer 20 serves as the starting point for subsequent wafer dicing and cracking. By optimizing the laser and optical path system, the first modified layer 20 can be confined inside the wafer, preventing thermal damage to the wafer surface and bottom surface. Then, external force is used to guide the cracks to the wafer surface and bottom surface, thereby separating the wafer into the required size. The first modified layer 20 can be composed of a densely packed ablation lattice or a crack layer.

[0111] During the process of irradiating the interior of the substrate 1 with a laser, the photon energy of the laser used must be less than the bandgap of the substrate 1 material and the first epitaxial layer 3 material. For example, the photon energy of the laser on the substrate 1 material must be less than the bandgap of SiC (2–2.7 eV); the photon energy of the laser on the first epitaxial layer 3 material must be less than the bandgap of one or more of SiC, GaN (3.39 eV), AlGaN (3.4–6.2 eV), and AlN (6.42 eV). This allows the laser to penetrate the surface of the substrate 1 and be focused inside the substrate 1 to form the first modified layer 20.

[0112] like Figure 13 , Figure 14 As shown, before step S300, the method further includes step S600, in which the fourth release substrate 9 is fixed to the opposite sides of the base layer 1 through a temporary bonding process.

[0113] Specifically, external force can be applied to the fourth release substrate 9 to separate the base layer 1 from the first substrate 10 of a predetermined thickness along the first modified layer 20; wherein the fourth release substrate 9 is located on opposite sides of the base layer 1. The fourth release substrate 9 can be silicon carbide (SiC), sapphire, glass, metal, etc. The function of the fourth release substrate 9 is twofold: firstly, to protect the base layer 1 from breakage in subsequent processes; and secondly, to act as an auxiliary force during the subsequent release of the base layer 1, facilitating the application of external force to the fourth release substrate 9 to release the base layer 1.

[0114] Step S600 can be performed before step S200. When the distance between the first modified layer 20 and the surface of the substrate 1 is small (e.g., 50-150 μm), the first substrate 10 is prone to cracking due to stress in the first modified layer 20 during laser processing. In this case, step S600 can be performed first. Before laser processing, a fourth release substrate 9 made of a transparent material that lasers can penetrate, such as silicon carbide (SiC), sapphire, or glass, is required. The fourth release substrate 9 made of such material is bonded to the surface of the substrate 1. The bonding process can increase the strength of the substrate 1, thereby preventing the substrate 1 from cracking under laser stress.

[0115] like Figure 13 As shown, in step S300, the first substrate 10 with a preset thickness range is separated from the base layer 1 along the first modified layer 20.

[0116] Specifically, under normal processing conditions, a silicon carbide (SiC) layer with a thickness of 500 μm is typically chosen as the substrate layer 1 to ensure that bending or cracking does not occur during the subsequent fabrication of the first device 17 on the first epitaxial layer 3. After the first device 17 is fabricated, the substrate layer 1 needs to be ground to reduce the thickness of the semiconductor element from 500 μm to 50 μm to 150 μm. Due to the substrate layer 1 being made of materials such as silicon carbide (SiC), which has a Mohs hardness of 9.5, the grinding wheel needs to be made of relatively expensive diamond material, resulting in lower grinding efficiency and wheel lifespan. Furthermore, the grinding process also leads to significant waste of silicon carbide (SiC) material, increasing costs.

[0117] In this embodiment, by incident a laser from either side of the substrate layer 1, the laser processes a first modified layer 20 within the substrate layer 1, directly producing a first substrate 10 of a predetermined thickness range, typically 50 μm to 150 μm. This improves processing efficiency, and by polishing the peeled surface of the first substrate 10, only the defective areas after laser treatment need to be smoothed to obtain the first substrate 10 of the predetermined thickness range, effectively reducing excessive material waste.

[0118] like Figure 13 , Figure 15 As shown, after step S300, the method further includes: step S700, polishing the release surface of the first substrate 10; and fixing the release surface of the first substrate 10 onto the fourth support substrate 16 through a temporary bonding process.

[0119] Specifically, polishing the release surface of the first substrate 10 removes defective areas caused by laser treatment and obtains a smooth surface, ensuring the quality of the subsequently fabricated semiconductor devices. After polishing the release surface of the first substrate 10, a temporary bonding process is used to fix the release surface of the first substrate 10 onto the fourth support substrate 16. The fourth support substrate 16 is used to support the first substrate 10. Since the first substrate 10 is relatively thin, the fourth support substrate 16 ensures that bending or cracking will not occur during the subsequent growth of the first epitaxial layer 3 on the first substrate 10 and the fabrication of the first device 17 on the first epitaxial layer 3.

[0120] like Figures 13 to 15 As shown, before step S400, the method further includes step S800, in which the fourth stripping substrate 9 is separated from the first substrate 10 by a bonding release process.

[0121] After the fourth stripping substrate 9 separates from the remaining substrate layer 2, the remaining substrate layer 2 can continue to undergo subsequent processing steps. After the fourth stripping substrate 9 separates from the first substrate 10, the subsequent step S400 can be performed to grow and form the first epitaxial layer 3 on the first substrate 10.

[0122] Specifically, the first epitaxial layer 3 can be a homogeneous epitaxial layer, that is, the first epitaxial layer 3 and the substrate layer 1 are made of the same material; for example, the substrate layer 1 is made of silicon carbide (SiC) material, and the first epitaxial layer 3 is also made of silicon carbide (SiC) material; the first epitaxial layer 3 can also be a heterogeneous epitaxial layer, that is, the first epitaxial layer 3 and the substrate layer 1 are made of different materials; for example, the substrate layer 1 is made of silicon carbide (SiC) material, while the first epitaxial layer 3 is made of a different material than the substrate layer 1, such as one or more of gallium nitride (GaN), aluminum gallium nitride (AlGaN), aluminum nitride (AlN), etc.

[0123] The order of steps S700 and S800 can be interchanged; executing step S700 first or step S800 first will achieve the same effect.

[0124] like Figure 13 , Figure 15 As shown, in step S500, a first device 17 is fabricated on the surface of the first epitaxial layer 3. Specifically, the first device 17 can be a bipolar junction transistor (BJT), a metal-oxide-semiconductor field-effect transistor (MOSFET), or the like.

[0125] Following step S500, the process further includes step S900, in which the first substrate 10 is separated from the fourth supporting substrate 16 through a bonding release process. This completes the fabrication of the semiconductor device.

[0126] While the disclosure is as stated above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of this disclosure, and all such changes and modifications will fall within the protection scope of this invention.

Claims

1. A method for fabricating a semiconductor element, characterized in that, include: The first epitaxial layer is grown on one side of the basal layer; The first release substrate is fixed to the surface of the first epitaxial layer and the base layer through a temporary bonding process; A first modified layer is formed within the substrate layer using a laser. A first substrate with a predetermined thickness range is separated from the base layer along the first modified layer; wherein, the first epitaxial layer is located on the first substrate; The release surface of the first substrate is polished; The release surface of the first substrate is fixed to the first support substrate through a temporary bonding process; A first device is fabricated on the surface of the first epitaxial layer; The first substrate is separated from the first support substrate by a debonding process.

2. The method for fabricating a semiconductor element according to claim 1, characterized in that, Before fabricating the first device on the surface of the first epitaxial layer, the process further includes: The first stripped substrate is separated from the first epitaxial layer by a bonding release process.

3. The method for fabricating a semiconductor element according to claim 1, characterized in that, Also includes: A second epitaxial layer is grown on the remaining basal layer surface; A second modified layer is formed within the remaining substrate layer using a laser; The remaining base layer is separated along the second modified layer to form a second substrate with a predetermined thickness range; wherein the second epitaxial layer is located on the second substrate; A second device is fabricated on the surface of the second epitaxial layer.

4. The method for preparing a semiconductor element according to claim 3, characterized in that, Before growing the second epitaxial layer on the remaining substrate surface, the process also includes: The remaining base layer surface is then polished.

5. The method for preparing a semiconductor element according to claim 3, characterized in that, Before separating the remaining base layer along the second modified layer, the process further includes: The second release substrate is fixed to the surface of the second epitaxial layer and the remaining base layer through a temporary bonding process.

6. The method for fabricating a semiconductor element according to claim 5, characterized in that, Before fabricating the second device on the surface of the second epitaxial layer, the process further includes: The second stripped substrate is separated from the second epitaxial layer by a bonding release process.

7. The method for preparing a semiconductor element according to claim 3, characterized in that, Before fabricating the second device on the surface of the second epitaxial layer, the process further includes: The peeling surface of the second substrate is polished; The release surface of the second substrate is fixed to the second support substrate through a temporary bonding process.

8. The method for preparing a semiconductor element according to claim 7, characterized in that, After fabricating the second device on the surface of the second epitaxial layer, the process further includes: The second substrate is separated from the second support substrate by a debonding process.

9. A method for fabricating a semiconductor element, characterized in that, include: The first epitaxial layer and the third epitaxial layer are grown on opposite sides of the basal layer, respectively; The third release substrate is fixed to the surfaces of the first epitaxial layer and the third epitaxial layer respectively through a temporary bonding process; A first modified layer is formed within the substrate layer using a laser. The base layer is separated along the first modified layer to form a first substrate and a third substrate with a predetermined thickness range; Wherein, the first epitaxial layer is disposed on the first substrate, and the third epitaxial layer is disposed on the third substrate; The peeling surfaces of the first substrate and the third substrate are polished; Through a temporary bonding process, the release surface of the first substrate is fixed to the third support substrate, and the release surface of the third substrate is fixed to the fourth support substrate. By performing a debonding process, the third support substrate is separated from the first substrate, and the fourth support substrate is separated from the third substrate; A first device is fabricated on the surface of the first epitaxial layer, and a third device is fabricated on the surface of the third epitaxial layer.

10. The method for fabricating a semiconductor element according to claim 9, characterized in that, Before fabricating a first device on the surface of the first epitaxial layer, and before fabricating a third device on the surface of the third epitaxial layer, the method further includes: By performing a bonding release process, the third stripping substrate is separated from the first epitaxial layer and the third epitaxial layer, respectively.

11. A method for fabricating a semiconductor element, characterized in that, include: The first modified layer is formed within the substrate using a laser; The fourth release substrate is fixed to the opposite sides of the base layer through a temporary bonding process; The base layer is separated along the first modified layer to form a first substrate with a predetermined thickness range; The release surface of the first substrate is polished; The release surface of the first substrate is fixed to the fourth support substrate through a temporary bonding process; A first epitaxial layer is grown and formed on the first substrate; A first device is fabricated on the surface of the first epitaxial layer; The first substrate is separated from the fourth support substrate by a debonding process.

12. The method for fabricating a semiconductor element according to claim 11, characterized in that, Before growing the first epitaxial layer on the first substrate, the method further includes: The fourth stripping substrate is separated from the first substrate by a debonding process.

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