Method for manufacturing silicon carbide wafer
By forming a thermal separation layer in the silicon carbide epitaxial layer and using a chemical mechanical polishing process, the problems of process yield loss and defect measurement difficulties in silicon carbide wafers after transplantation are solved, and the manufacturing of high-quality silicon carbide wafers is achieved.
Patent Information
- Application Number
- CN202410289950.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-03-14
- Publication Date
- 2025-09-16
AI Technical Summary
After silicon carbide wafers are transplanted to another substrate, there are problems with subsequent process yield loss and difficulty in defect measurement.
An ion implantation process is used to form a thermal segmentation layer in the silicon carbide epitaxial layer, which is then decomposed by heating. Combined with a temporary substrate bonding and chemical mechanical polishing process, the silicon carbide epitaxial layer is segmented and transferred to a permanent substrate. Finally, the surface is restored to flatness through a CMP process.
The subsequent process yield of silicon carbide wafers is improved, defect measurement is simplified, and high-quality silicon carbide wafers are obtained.
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Figure CN120656935A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a semiconductor manufacturing method, in particular to a method for manufacturing a silicon carbide wafer. Background Art
[0002] Silicon carbide wafers are a substrate used in semiconductor manufacturing. This material possesses a range of advantageous properties, making it an ideal choice for high-temperature, high-voltage, and high-frequency applications. The manufacturing process for silicon carbide wafers involves growing a single crystal of silicon carbide to a specific size and thickness, then forming it into disc-shaped wafers for use in semiconductor device fabrication.
[0003] One of the main advantages of silicon carbide is its high thermal stability. Its ability to maintain stability under extreme temperature conditions makes it an excellent choice for high-temperature applications. Furthermore, silicon carbide has a high electron mobility, meaning that electrons move more quickly within the crystal, thus improving overall device performance.
[0004] Silicon carbide wafers also excel in high-power and high-frequency applications. Their superior electrical conductivity and heat dissipation properties make them ideal for manufacturing power electronics, such as high-power converters and transmission lines. Furthermore, silicon carbide exhibits excellent performance in radio frequency (RF) applications, making it a top choice for manufacturing high-frequency wireless communication devices.
[0005] The manufacturing process for silicon carbide wafers requires transplanting the silicon carbide epitaxial layer generated from the wafer substrate material to another surface. However, there are some problems after the silicon carbide epitaxial layer is bonded to the other substrate, which will cause a loss in subsequent process yield and increase the difficulty of defect measurement. Summary of the Invention
[0006] The present invention provides a method for manufacturing a silicon carbide wafer to solve the problems of the prior art.
[0007] According to some embodiments of the present invention, a method for manufacturing a silicon carbide wafer includes: forming a silicon carbide epitaxial layer on a first silicon carbide substrate; forming a thermal partition layer in the silicon carbide epitaxial layer using an ion implantation process; bonding the silicon carbide epitaxial layer using a temporary substrate; heating to decompose the thermal partition layer, thereby dividing the silicon carbide epitaxial layer into an upper silicon carbide epitaxial layer and a lower silicon carbide epitaxial layer; and performing a first chemical mechanical polishing process on the upper silicon carbide epitaxial layer bonded to the temporary substrate.
[0008] According to some embodiments of the present invention, a method for manufacturing a silicon carbide wafer includes: forming a silicon carbide epitaxial layer on a first silicon carbide substrate; forming a thermal partition layer in the silicon carbide epitaxial layer using an ion implantation process; bonding the silicon carbide epitaxial layer using a temporary substrate; heating to decompose the thermal partition layer, thereby dividing the silicon carbide epitaxial layer into an upper silicon carbide epitaxial layer and a lower silicon carbide epitaxial layer; performing a first chemical mechanical polishing process on the upper silicon carbide epitaxial layer bonded to the temporary substrate; and bonding a second silicon carbide substrate to the surface of the upper silicon carbide epitaxial layer treated by the first chemical mechanical polishing process.
[0009] According to some embodiments of the present invention, a method for manufacturing a silicon carbide wafer includes: forming a silicon carbide epitaxial layer on a first silicon carbide substrate; forming a thermal partition layer in the silicon carbide epitaxial layer using an ion implantation process; bonding the silicon carbide epitaxial layer using a temporary substrate; heating to decompose the thermal partition layer, thereby dividing the silicon carbide epitaxial layer into an upper silicon carbide epitaxial layer and a lower silicon carbide epitaxial layer; performing a first chemical mechanical polishing process on the upper silicon carbide epitaxial layer bonded to the temporary substrate; bonding a second silicon carbide substrate to the surface of the upper silicon carbide epitaxial layer treated by the first chemical mechanical polishing process; bonding a second silicon carbide substrate to the upper silicon carbide epitaxial layer bonded to the temporary substrate; and removing the temporary substrate and performing a second chemical mechanical polishing process on the exposed surface of the upper silicon carbide epitaxial layer.
[0010] According to some embodiments of the present invention, ions used in the ion implantation process include hydrogen ions, helium ions, or a combination thereof.
[0011] According to some embodiments of the present invention, ions used in the ion implantation process include hydrogen ions.
[0012] According to some embodiments of the present invention, ions used in the ion implantation process include helium ions.
[0013] According to some embodiments of the present invention, the silicon carbide epitaxial layer is a single crystal silicon carbide epitaxial layer.
[0014] According to some embodiments of the present invention, an extension direction of the thermal segmentation layer is perpendicular to a central axis of the first silicon carbide substrate.
[0015] According to some embodiments of the present invention, the manufacturing method further includes: bonding a second silicon carbide substrate on the upper silicon carbide epitaxial layer bonded to the temporary substrate, wherein the temporary substrate and the second silicon carbide substrate are respectively located on two opposite surfaces of the upper silicon carbide epitaxial layer.
[0016] According to some embodiments of the present invention, the manufacturing method further includes: removing the temporary substrate, so that the upper silicon carbide epitaxial layer is located on the second silicon carbide substrate.
[0017] According to some embodiments of the present invention, the manufacturing method further includes: performing a chemical mechanical polishing process on the upper silicon carbide epitaxial layer on the second silicon carbide substrate.
[0018] According to some embodiments of the present invention, the manufacturing method further includes: performing a chemical mechanical polishing process on the lower silicon carbide epitaxial layer on the first silicon carbide substrate.
[0019] According to some embodiments of the present invention, the temporary substrate and the second silicon carbide base material are respectively located on two opposite surfaces of the upper silicon carbide epitaxial layer.
[0020] In summary, the method for manufacturing a silicon carbide wafer of the present invention utilizes epitaxial growth technology to grow a thicker, high-quality silicon carbide epitaxial layer, and uses wafer separation technology to implant a high dose of H through an ion implantation process. + or He + The silicon carbide wafer is injected and bonded to a temporary substrate. The temporary substrate with the silicon carbide epitaxial layer is peeled off by heating to form two silicon carbide wafers. The silicon carbide epitaxial layer on the temporary substrate is transferred to a permanent silicon carbide substrate. Finally, the silicon carbide substrate and the original silicon carbide wafer are subjected to CMP to remove the damaged layer and restore the surface of the epitaxial layer to a flat state, thus obtaining two silicon carbide wafers with high-quality epitaxial layers.
[0021] The above description will be described in detail below with reference to implementation examples, and a further explanation of the technical solution of the present invention will be provided. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] To make the above and other objects, features, advantages and embodiments of the present invention more apparent, the accompanying drawings are described as follows:
[0023] Figure 1A 、 Figure 1B A cross-sectional view illustrating steps of a method for manufacturing a silicon carbide wafer according to an embodiment of the present invention; and
[0024] Figure 2 FIG1 is a flow chart illustrating a method for manufacturing a silicon carbide wafer according to an embodiment of the present invention. DETAILED DESCRIPTION
[0025] For a more detailed and complete description of the present invention, reference is made to the accompanying drawings and various embodiments described below. Like numbers in the drawings represent like or similar elements. Well-known elements and steps are not described in the embodiments to avoid unnecessary limitations on the present invention. In the embodiments and claims, unless the context specifically dictates otherwise, the words "a," "an," and "the" may refer to a single or multiple person.
[0026] Please also refer to Figure 1A 、 Figure 1Band Figure 2 , Figure 1A 、 Figure 1B 1 is a cross-sectional view illustrating steps of a method 100 for manufacturing a silicon carbide wafer according to an embodiment of the present invention. Figure 2 The present invention provides a flow chart of a method 200 for manufacturing a silicon carbide wafer according to an embodiment of the present invention. To address the issues of subsequent process yield loss and increased difficulty in defect measurement caused by transplanting a silicon carbide epitaxial layer to another substrate, the present invention provides an improved method for manufacturing a silicon carbide wafer.
[0027] exist Figure 1A Step 110 and Figure 2 In step 210, a silicon carbide epitaxial layer 103 is formed on the first silicon carbide substrate 101. A silicon carbide wafer is a semiconductor wafer made of silicon carbide material, which is typically used to manufacture components for high-power, high-frequency applications, such as power amplifiers and radio frequency components. The method of forming a silicon carbide epitaxial layer involves techniques such as chemical vapor deposition (CVD) or physical vapor deposition (PVD). In some embodiments of the present invention, the silicon carbide epitaxial layer 103 is a single-crystal silicon carbide epitaxial layer. The silicon carbide epitaxial layer 103 can generally be divided into two types: single crystal and polycrystalline. The single-crystal epitaxial layer has a relatively complete crystalline structure and provides better electrical properties, especially in high-temperature and high-power applications. In high-power, high-frequency applications, the performance of single-crystal silicon carbide may be more critical.
[0028] In the SiC wafer process, a common method is to use chemical vapor deposition. This method includes the following steps.
[0029] Pretreatment: Clean the wafer surface to ensure it is free of dust and impurities.
[0030] Introducing precursor gas: In a high vacuum or nitrogen environment, a silicon carbide precursor gas (such as monosilane, dimethylsilyl ether) is introduced into the reaction chamber.
[0031] Deposition of silicon carbide film: The precursor gas decomposes and deposits on the wafer surface, forming a silicon carbide film. This step is usually performed at high temperature to promote the reaction.
[0032] Epitaxial growth: Repeatedly introducing precursor gases and depositing thin films gradually forms a silicon carbide epitaxial layer. Reaction conditions, such as temperature and gas flow, are controlled to ensure uniformity and thickness of the epitaxial layer.
[0033] Physical vapor deposition can also be used to prepare silicon carbide films, in which a solid source material or target is used, and the source material is excited to form a vapor phase, which is then deposited on the wafer surface.
[0034] The fabrication of SiC wafers involves prior processing of the wafer and then depositing a SiC thin film using techniques such as CVD or PVD, ultimately forming a SiC epitaxial layer.
[0035] exist Figure 1A Step 112 and Figure 2 In step 212, a heat partition layer 105 is formed in the silicon carbide epitaxial layer 103 using an ion implantation process. In some embodiments of the present invention, the extension direction of the heat partition layer 105 is perpendicular to the central axis 101a of the first silicon carbide substrate 101 (for example, the central axis of a disk-shaped silicon carbide substrate). In some embodiments of the present invention, the dose of ions implanted is in the range of 1E15 to 5E17 [atom / cm2]. Using an ion implantation process to form a heat partition layer in a silicon carbide epitaxial layer is a technique for changing the properties of a material, typically using hydrogen ions (H + ), helium ions (He + ) or a combination thereof, the following is an example process.
[0036] Prepare the SiC epitaxial layer: Ensure that the SiC epitaxial layer has been grown on the wafer and is of the required thickness and quality.
[0037] Select ion species: Select appropriate ion species based on the characteristics of the thermal separation layer to be formed.
[0038] Energy and dose control: Adjust the energy and dose of ion implantation. Energy control affects the penetration depth of ions, while dose affects the density of implanted ions. Adjusting these parameters will affect the depth and properties of the resulting thermal segmentation layer.
[0039] Ion implantation process: Under specific vacuum conditions, selected ions are implanted into the silicon carbide epitaxial layer to form a thermal segmentation layer.
[0040] Heat treatment: After ion implantation, heat treatment is performed to repair the crystal lattice and stabilize weakened areas. This helps ensure the stability of the formed thermal separation layer in subsequent processes.
[0041] exist Figure 1A Step 114 and Figure 2 In step 214, a temporary substrate 106 is used to bond the silicon carbide epitaxial layer 103. This step facilitates the subsequent transfer of the divided half of the silicon carbide epitaxial layer 103 to another silicon carbide substrate when the silicon carbide epitaxial layer 103 is divided.
[0042] exist Figure 1A Step 116 and Figure 2 In step 216, the heat is applied to decompose the thermal segmentation layer 105, thereby segmenting the silicon carbide epitaxial layer 103 into an upper silicon carbide epitaxial layer 103b and a lower silicon carbide epitaxial layer 103a.
[0043] exist Figure 1A Step 118 and Figure 2In step 218, the upper silicon carbide epitaxial layer 103b bonded to the temporary substrate 106 undergoes a first chemical mechanical polishing process. This chemical mechanical polishing (hereinafter referred to as CMP) process is used to improve the surface flatness and processing accuracy of the upper silicon carbide epitaxial layer 103b and remove defects or damage that may occur during the decomposition of the thermally separated layer 105. The following are some exemplary steps.
[0044] Prepare the CMP process machine: Set up the CMP process machine, including appropriate abrasive, grinding wheel, grinding wheel speed, and pressure control parameters.
[0045] Coarse grinding stage: Start with coarse grinding using larger grain abrasives to quickly remove surface irregularities.
[0046] Intermediate grinding stage: Switch to smaller particle abrasives for intermediate grinding, gradually reducing surface roughness and achieving higher flatness.
[0047] Fine grinding stage: Use finer abrasives for fine grinding to further improve surface smoothness and processing accuracy.
[0048] Cleaning and inspection: After the CMP process is completed, cleaning is performed to remove residual abrasive and contaminants, and then the processed upper SiC epitaxial layer is inspected.
[0049] exist Figure 1A Step 120 and Figure 2 In step 220, a second silicon carbide substrate 109 is bonded to the upper silicon carbide epitaxial layer 103b bonded to the temporary substrate 106. The second silicon carbide substrate 109 is bonded to the surface of the upper silicon carbide epitaxial layer 103b that has been treated by the chemical mechanical polishing process. The temporary substrate 106 and the second silicon carbide substrate 109 are located on opposite surfaces of the upper silicon carbide epitaxial layer. In some embodiments of the present invention, the second silicon carbide substrate 109 and the first silicon carbide substrate 101 are made of the same material.
[0050] exist Figure 1B Step 122 and Figure 2 In step 222, the temporary substrate 106 is removed so that the upper silicon carbide epitaxial layer 103b is located on the second silicon carbide substrate 109. The temporary substrate 106 may be removed in the following manner, for example.
[0051] Chemical wet etching uses specific chemical solutions that selectively attack the temporary substrate without damaging the upper SiC epitaxial layer. For example, wet etching can selectively etch silicon or other substrate materials. This requires careful selection of chemical solutions to ensure that only the temporary substrate is removed without affecting the upper SiC layer.
[0052] Mechanical peeling: Using mechanical force to separate the temporary substrate. This may involve applying mechanical shock or stress to peel the substrate. This requires careful control of the direction and magnitude of the force to avoid damaging the SiC epitaxial layer.
[0053] Thermal treatment: By treating the temporary substrate with high temperature, the substrate material will have specific thermal expansion characteristics, thus facilitating separation. This method is usually combined with chemical wet etching to enhance the effect.
[0054] Laser lift-off: This method uses a laser beam focused on a temporary substrate, which generates heat in the light-absorbing areas, facilitating lift-off. This process also requires careful control of energy and timing.
[0055] Ion implantation: The ion implantation process changes the properties of the temporary substrate material, making it easier to peel off.
[0056] When performing these methods, special attention needs to be paid to selecting appropriate parameters to ensure effective and controlled removal of the temporary substrate while protecting the integrity of the upper SiC epitaxial layer.
[0057] exist Figure 1B Step 124 and Figure 2 In step 224, a chemical mechanical polishing process is performed on the lower silicon carbide epitaxial layer 103a on the first silicon carbide substrate 101. Figure 1B Step 124 and Figure 2 In step 226, a chemical mechanical polishing process is performed on the upper silicon carbide epitaxial layer 103b on the second silicon carbide substrate 109. Steps 224 and 226 can be performed simultaneously or separately. The chemical mechanical polishing process removes the damaged layers of the lower silicon carbide epitaxial layer 103a and the upper silicon carbide epitaxial layer 103b to restore the surface of the epitaxial layer to a flat state, thereby obtaining two silicon carbide wafers. In the above process, the two opposite surfaces of the upper silicon carbide epitaxial layer 103b are respectively subjected to chemical mechanical polishing processes to solve problems such as bonding flatness, new defects on the surface of the bonded silicon carbide substrate, and uneven surface of the silicon carbide epitaxial layer.
[0058] In summary, the method for manufacturing a silicon carbide wafer of the present invention utilizes epitaxial growth technology to grow a thicker, high-quality silicon carbide epitaxial layer, and uses wafer separation technology to implant a high dose of H through an ion implantation process. + or He + The silicon carbide wafer is injected and bonded to a temporary substrate. The temporary substrate with the silicon carbide epitaxial layer is peeled off by heating to form two silicon carbide wafers. The silicon carbide epitaxial layer on the temporary substrate is transferred to a permanent silicon carbide substrate. Finally, the silicon carbide substrate and the original silicon carbide wafer are subjected to CMP to remove the damaged layer and restore the surface of the epitaxial layer to a flat state, thus obtaining two silicon carbide wafers with high-quality epitaxial layers.
[0059] Although the present invention has been disclosed above in terms of embodiments, this is not intended to limit the present invention. Any person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.
[0060]
Explanation of symbols
[0061] 100: Manufacturing method
[0062] 101: first silicon carbide substrate
[0063] 101a: Central axis
[0064] 103: Silicon carbide epitaxial layer
[0065] 103a: Lower silicon carbide epitaxial layer
[0066] 103b: Upper silicon carbide epitaxial layer
[0067] 105: Thermal separation layer
[0068] 106: Temporary substrate
[0069] 109: Second silicon carbide substrate
[0070] 110, 112, 114, 116, 118, 120, 122, 124: Steps
[0071] 200: Manufacturing method
[0072] 210, 212, 214, 216, 218, 220, 222, 224, 226: steps.
Claims
1. A method for manufacturing a silicon carbide wafer, characterized in that: Include: forming a silicon carbide epitaxial layer on a first silicon carbide substrate; forming a thermal partition layer in the silicon carbide epitaxial layer using an ion implantation process; bonding the silicon carbide epitaxial layer using a temporary substrate; heating to decompose the thermal segmentation layer, thereby segmenting the silicon carbide epitaxial layer into an upper silicon carbide epitaxial layer and a lower silicon carbide epitaxial layer; as well as A first chemical mechanical polishing process is performed on the upper silicon carbide epitaxial layer bonded to the temporary substrate.
2. A method for manufacturing a silicon carbide wafer, characterized in that: Include: forming a silicon carbide epitaxial layer on a first silicon carbide substrate; forming a thermal partition layer in the silicon carbide epitaxial layer using an ion implantation process; bonding the silicon carbide epitaxial layer using a temporary substrate; heating to decompose the thermal segmentation layer, thereby segmenting the silicon carbide epitaxial layer into an upper silicon carbide epitaxial layer and a lower silicon carbide epitaxial layer; performing a first chemical mechanical polishing process on the upper silicon carbide epitaxial layer bonded to the temporary substrate; as well as A second silicon carbide substrate is bonded to the surface of the upper silicon carbide epitaxial layer processed by the first chemical mechanical polishing process.
3. A method for manufacturing a silicon carbide wafer, characterized in that: Include: forming a silicon carbide epitaxial layer on a first silicon carbide substrate; forming a thermal partition layer in the silicon carbide epitaxial layer using an ion implantation process; bonding the silicon carbide epitaxial layer using a temporary substrate; heating to decompose the thermal segmentation layer, thereby segmenting the silicon carbide epitaxial layer into an upper silicon carbide epitaxial layer and a lower silicon carbide epitaxial layer; performing a first chemical mechanical polishing process on the upper silicon carbide epitaxial layer bonded to the temporary substrate; bonding a second silicon carbide substrate to the surface of the upper silicon carbide epitaxial layer treated by the first chemical mechanical polishing process; Bonding a second silicon carbide substrate on the upper silicon carbide epitaxial layer bonded to the temporary substrate; as well as The temporary substrate is removed, and a second chemical mechanical polishing process is performed on the exposed surface of the upper silicon carbide epitaxial layer.
4. The method for manufacturing a silicon carbide wafer according to claim 1, 2 or 3, wherein: Ions used in the ion implantation process include hydrogen ions, helium ions, or a combination thereof.
5. The method for manufacturing a silicon carbide wafer according to claim 1, 2 or 3, wherein: The silicon carbide epitaxial layer is a single crystal silicon carbide epitaxial layer.
6. The method for manufacturing a silicon carbide wafer according to claim 1, 2 or 3, wherein: An extending direction of the heat separation layer is perpendicular to a central axis of the first silicon carbide substrate.
7. The method for manufacturing a silicon carbide wafer according to claim 1, wherein: The method further comprises bonding a second silicon carbide substrate on the upper silicon carbide epitaxial layer bonded to the temporary substrate, wherein the temporary substrate and the second silicon carbide substrate are respectively located on two opposite surfaces of the upper silicon carbide epitaxial layer.
8. The method for manufacturing a silicon carbide wafer according to claim 2 or 7, wherein: The method further comprises: removing the temporary substrate so that the upper silicon carbide epitaxial layer is located on the second silicon carbide substrate.
9. The method for manufacturing a silicon carbide wafer according to claim 8, wherein: The method further comprises: performing a second chemical mechanical polishing process on the upper silicon carbide epitaxial layer on the second silicon carbide substrate.
10. The method for manufacturing a silicon carbide wafer according to claim 1 or 2, wherein: The method further comprises: performing a second chemical mechanical polishing process on the lower silicon carbide epitaxial layer on the first silicon carbide substrate.