CN109545680B - Rapid preparation method of high-flatness and low-damage monocrystalline silicon carbide substrate - Google Patents
Rapid preparation method of high-flatness and low-damage monocrystalline silicon carbide substrate Download PDFInfo
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- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
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- H01L21/30625—With simultaneous mechanical treatment, e.g. mechanico-chemical polishing
Abstract
The invention provides a rapid preparation method of a single crystal silicon carbide substrate with high flatness and low damage, which is characterized by comprising the following steps: carrying out full-consolidation abrasive processing on the monocrystalline silicon carbide, and then carrying out chemical mechanical polishing treatment to obtain the monocrystalline silicon carbide substrate with high flatness and low damage; wherein the fixed abrasive machining includes wire cutting and wheel grinding, and abrasive grains are fixed on the cutting wire and abrasive grains are fixed on the grinding wheel. The single crystal silicon carbide substrate prepared by the preparation method provided by the invention has the advantages of low surface roughness, small scratch die ratio, pit ratio and bump, good surface type data, small thickness deviation, small curvature and small warping degree.
Description
Technical Field
The invention relates to the technical field of crystal material processing, in particular to a rapid preparation method of a single crystal silicon carbide substrate with high flatness and low damage.
Background
The monocrystalline silicon carbide is one of the most important third-generation semiconductor materials, and has excellent properties of large forbidden bandwidth, high saturated electron mobility, strong breakdown field, high thermal conductivity and the like, so that the monocrystalline silicon carbide has wide application prospects in the fields of power electronics, radio-frequency devices, photoelectronic devices and the like.
At present, the commercial single crystal silicon carbide mostly uses a PVT (physical vapor deposition) growth method, and then an open-box ready-to-use silicon carbide substrate is formed through end face machining, multi-line cutting, grinding, mechanical polishing, chemical mechanical polishing, cleaning and packaging. Because the mohs of the monocrystalline silicon carbide is 9.2, the monocrystalline silicon carbide is second to diamond in nature, the difficulty of physical processing is very high, and the silicon carbide has high chemical stability, such as acid-base resistance and oxidation resistance, so that the difficulty of Chemical Mechanical Polishing (CMP) is greatly increased. Chemical mechanical polishing is the only global planarization polishing method at present, and uses chemical polishing solution, which contains chemical agent with strong oxidizing property and particles as abrasive. In the polishing process, chemical action and mechanical action act on the surface of the wafer simultaneously to remove a damaged layer on the surface of the wafer.
In view of the processing difficulty of silicon carbide materials, the methods of primary processing → sand line cutting → free abrasive grinding → copper disc polishing → tin disc polishing → rough CMP → fine CMP are frequently used at present, and have the problems of complicated processing steps, low efficiency, difficulty in cleaning the free abrasive in the processing process, low one-time pass rate, poor surface shape (TTV/Bow/Warp), difficulty in eliminating subsurface damage and the like. If damage exists on the surface of the substrate after processing is finished, the damage can directly spread to the surface of the epitaxial wafer in a triangular defect mode, and a large number of unqualified areas are formed. In the next step of manufacturing chips, the defective areas greatly reduce the chip yield, which is the primary factor affecting the chip yield.
In the prior art, because the abrasive wire cutting is adopted, which is a cutting mode similar to grinding, the cutting force is very weak, so that the processing efficiency is greatly reduced; in the free abrasive grinding process, the large particles of the free abrasive cause deep scratches, which are difficult to remove in the next process. The copper disc and the tin disc are single-side processing methods, and due to the fact that the disc surface is soft, flatness control of the disc surface is poor, and the wafer surface type (TTV/LTV/BOW/Warp) is seriously influenced.
The conventional alkaline CMP process has been in conflict with surface quality and removal rate: the removal rate can be improved by using a high-hardness abrasive, but surface damage can be caused; high quality surfaces can be obtained with low hardness abrasives, but the removal rate is very low. The surface of the finally obtained wafer has a fatal influence on the application if a damaged layer exists.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a rapid preparation method of a high-flatness and low-damage single-crystal silicon carbide substrate, which comprises the following steps: carrying out full-consolidation abrasive processing on the monocrystalline silicon carbide, and then carrying out chemical mechanical polishing treatment to obtain the monocrystalline silicon carbide substrate with high flatness and low damage; wherein the fixed abrasive machining includes wire cutting and wheel grinding, and abrasive grains are fixed on the cutting wire and abrasive grains are fixed on the grinding wheel. The single crystal silicon carbide substrate prepared by the preparation method provided by the invention has the advantages of low surface roughness, small scratch die (unqualified square) occupation ratio, pit occupation ratio and bump, good surface type data, small thickness deviation, small bending degree and small warping degree.
In order to achieve the above purposes, the technical scheme adopted by the invention is as follows:
in one aspect, the invention provides a method for rapidly preparing a high-flatness low-damage monocrystalline silicon carbide substrate, which comprises the following steps: carrying out full-consolidation abrasive processing on the monocrystalline silicon carbide, and then carrying out chemical mechanical polishing treatment to obtain the monocrystalline silicon carbide substrate with high flatness and low damage; wherein the fixed abrasive machining includes wire cutting and wheel grinding, and abrasive grains are fixed on the cutting wire and abrasive grains are fixed on the grinding wheel.
Further, the abrasive particles are selected from one or more of silicon oxide, aluminum oxide, cerium oxide, silicon carbide, boron carbide, zirconium oxide and diamond.
Further, before diamond wire cutting is carried out on the single crystal silicon carbide, primary processing is carried out on the single crystal silicon carbide, wherein the primary processing adopts a fixed abrasive processing mode.
Further, the wire cutting is specifically diamond wire cutting.
Furthermore, abrasive particles are added into cooling liquid used in the diamond wire cutting process. Wherein the mass percentage concentration of the abrasive particles in the cooling liquid is 2-10%. The abrasive particles may be one or more of alumina, diamond, boron carbide. The particle size of the abrasive particles is 50-100 nm. Preferably, the abrasive particles have a particle size of 60 to 80 nm.
Furthermore, the tension of the cutting wire in the diamond wire cutting processing step is 22-40N, the wire running speed is 1200-1800m/min, the swing angle is 1-10 degrees, the feed speed is 5-15mm/h, and the diameter of the diamond wire is 0.12-0.28 mm. Preferably, the tension of the cutting line in the diamond wire cutting processing step is 30-40N, the line running speed is 1300-1600m/min, the swing angle is 3-8 degrees, the feed speed is 8-12mm/h, and the diameter of the diamond wire is 0.15-0.20 mm. More preferably, the diamond wire cutting process step comprises cutting wire tension of 33-38N, wire running speed of 1400-1500m/min, swing angle of 4-6 degrees, feed speed of 9-11mm/h, and diamond wire diameter of 0.15-0.18 mm.
The principle of the diamond wire cutting method is as follows: a diamond wire (made of nickel) is used for forming a wire net with equal intervals between the groove wheels, and the wire net reciprocates at a high speed to achieve the cutting effect. According to the invention, abrasive particles with a certain concentration are added into the cooling liquid, the particles can be alumina, diamond, boron carbide and the like, the mass percentage concentration is 2-10%, and the traditional mortar cutting method and the solidification mortar wire cutting method are combined, so that the roughness of a cutting surface is lower, and the cutter mark rate is lower.
Further, the grinding wheel grinding comprises two steps of rough grinding and finish grinding. Wherein, the consolidated abrasive in the rough grinding is obtained by consolidating abrasive grains of 1000 meshes to 5000 meshes on a grinding wheel; the fixed abrasive in the fine grinding is formed by fixing abrasive particles of 20000 meshes to 30000 meshes on a grinding wheel. Preferably, the fixed abrasive in the coarse grinding is obtained by fixing abrasive particles of 2000 meshes to 4000 meshes on a grinding wheel; the fixed abrasive in the fine grinding is obtained by fixing 25000-30000-mesh abrasive particles on a grinding wheel. More preferably, the fixed abrasive in the rough grinding is abrasive grains with 3000 meshes fixed on a grinding wheel; the fixed abrasive in the fine grinding is abrasive grains of 28000 meshes fixed on a grinding wheel.
Furthermore, the rotation speed of the grinding wheel in the coarse grinding step is 1000-2000rpm, and the feed speed is 0.2-1 um/s; the rotation speed of the grinding wheel in the fine grinding step is 1000-. Preferably, the rotation speed of the grinding wheel in the coarse grinding step is 1300-1600rpm, and the feed speed is 0.6-0.8 um/s; the rotation speed of the grinding wheel in the fine grinding step is 1000-.
The Grinding wheel Grinding (Grinding) principle is as follows: the wafer was subjected to single-side processing using a resin wheel containing diamond particles. The wafer rotates at low speed, the grinding wheel rotates at high speed, and grinding wheels with different meshes can obtain different processing surface roughness.
Further, the polishing solution used in the acidic chemical mechanical polishing step includes: abrasive, oxidant, water-soluble acidic polymer, dispersant and RO water; wherein, the mass percentage concentration of the grinding material is 1-30%; the abrasive is selected from one or more of silicon oxide, aluminum oxide, diamond particles, cerium oxide, silicon carbide, boron carbide, zirconium oxide and diamond; the oxidant is selected from one or more of hydrogen peroxide, potassium permanganate, nitric acid, hydrochloric acid and potassium perchlorate; the water-soluble acidic polymer is selected from one or more of carboxyl polymer and sulfonic polymer; the dispersing agent is selected from one or more of higher alcohol, polyvinyl alcohol and polyethylene glycol, and the mass percentage concentration of the dispersing agent is 0.2-1%.
The polishing solution of the present invention is added with a water-soluble acidic polymer, which not only can control the pH value of the polishing solution, but also can maintain the dispersion stability of the polishing solution. After the water-soluble acidic polymer is added, the pH value of the polishing solution is always kept within the range of 2-4 in the chemical mechanical polishing process, the dispersion uniformity of the abrasive in the polishing solution is basically not influenced, and the possibility of scratches and damages on the polished surface of a product is reduced.
Furthermore, the polishing solution can also comprise the following components: corrosion inhibitors, viscosity modifiers, surfactants, antimicrobial agents, and the like.
Further, the pH value of the acidic chemical mechanical polishing solution in the acidic chemical mechanical polishing treatment step is 2-4, the rotating speed is 20-50rpm, and the pressure is 200-2The material flow is 3-10L/min. Preferably, the pH value of the acidic chemical mechanical polishing solution in the acidic chemical mechanical polishing treatment step is 2.5-3.5, the rotation speed is 25-45rpm, and the pressure is 250-2The material flow is 5-7L/min. More preferably, the pH value of the acidic chemical mechanical polishing solution in the acidic chemical mechanical polishing treatment step is 3.0-3.5, the rotation speed is 30-40rpm, and the pressure is 400 g/cm-2The material flow is 6-7L/min.
On the other hand, the invention also provides a high-flatness low-damage monocrystalline silicon carbide substrate which is prepared by the rapid preparation method of the high-flatness low-damage monocrystalline silicon carbide substrate.
Furthermore, the diameter of the substrate is more than or equal to 100mm, the surface roughness is less than or equal to 0.2nm, no subsurface damage layer exists, the proportion of small scratches is less than 10%, and the proportion of pit is less than 0.1/cm2The bump ratio is less than 0.1 pieces/cm2。
Further, the surface roughness is less than or equal to 0.10nm, the proportion of fine scratches of the substrate is less than 10 percent, and the proportion of pit is less than 0.1/cm2The bump ratio is less than 0.1 per cm2。
Furthermore, the surface roughness is less than or equal to 0.09nm, the proportion of the fine scratches is less than 8 percent, and the proportion of the pit is less than 0.08/cm2The bump ratio is less than 0.08 pieces/cm2。
Furthermore, the surface roughness is less than or equal to 0.07nm, the proportion of the fine scratches is less than 6 percent, and the proportion of the pit is less than 0.05 per cm2The bump ratio is less than 0.05 pieces/cm2。
Furthermore, the surface roughness is less than or equal to 0.05nm, the proportion of the fine scratches is less than 4 percent, and the proportion of the pit is less than 0.03/cm2The bump ratio is less than 0.03 pieces/cm2。
Further, the thickness of the substrate is less than 500 um. Preferably, the substrate thickness is less than 350 um. More preferably, the substrate thickness is less than 200 um. More preferably, the substrate thickness is less than 100 um. More preferably, the substrate thickness is less than 50 um.
Further, the diameter of the substrate is one of 4 inches, 6 inches, and 8 inches. Preferably, the substrate has a diameter of one of 6 inches and 8 inches.
Further, the surface type data of the substrate: TTV (total thickness variation) < 5um, LTV (local thickness variation) (1 cm) < 2um, Bow (Bow) < 20um, and Warp (Warp) < 40um for a 4-inch substrate. TTV < 10um, LTV (1 cm x 1 cm) < 2um, Bow < 40um, and Warp < 60um for 6-inch substrates. TTV < 10um, LTV (1 cm x 1 cm) < 2um, Bow < 50um, and Warp < 70um for an 8-inch substrate.
Further, the surface type data of the substrate: TTV < 3um, LTV (1 cm x 1 cm) < 1.5um, Bow < 15um, and Warp < 30um for a 4-inch substrate. TTV < 5um, LTV (1 cm x 1 cm) < 1.5um, Bow < 30um, and Warp < 50um for a 6-inch substrate. TTV < 6um, LTV (1 cm x 1 cm) < 1.5um, Bow < 40um, and Warp < 60um for an 8-inch substrate.
Further, the 4 inch substrate has TTV < 1um, LTV (1 cm x 1 cm) < 1um, Bow < 10um, and Warp < 20 um. TTV < 3um, LTV (1 cm x 1 cm) < 1um, Bow < 20um, and Warp < 30um for a 6-inch substrate. TTV < 4um, LTV (1 cm x 1 cm) < 1um, Bow < 30um, and Warp < 50um for an 8-inch substrate.
Further, the 4 inch substrate has TTV < 0.5um, LTV (1 cm x 1 cm) < 0.5um, Bow < 5um, and Warp < 10 um. TTV < 1um, LTV (1 cm x 1 cm) < 0.5um, Bow < 10um, and Warp < 15um for a 6-inch substrate. TTV < 2um, LTV (1 cm x 1 cm) < 0.5um, Bow < 20um, and Warp < 40um for an 8-inch substrate.
Further, the 4 inch substrate has TTV < 0.1um, LTV (1 cm x 1 cm) < 0.08um, Bow < 2um, and Warp < 5 um. TTV < 0.15um, LTV (1 cm x 1 cm) < 0.12um, Bow < 3um, and Warp < 8um for a 6-inch substrate. TTV < 1um, LTV (1 cm x 1 cm) < 0.5um, Bow < 5um, and Warp < 10um for an 8-inch substrate.
Further, the 4 inch substrate has TTV < 0.08um, LTV (1 cm x 1 cm) < 0.08um, Bow < 0.5um, and Warp < 1 um. TTV < 0.1um, LTV (1 cm x 1 cm) < 0.1um, Bow < 1um, and Warp < 2um for a 6-inch substrate. TTV < 0.5um, LTV (1 cm x 1 cm) < 0.2um, Bow < 3um, and Warp < 5um for an 8-inch substrate.
The invention has the following beneficial effects:
1. the invention adopts a full-fixed abrasive processing method, which can greatly improve the processing efficiency; the fixed abrasive replaces the traditional free abrasive for grinding and polishing, and has the advantages that the abrasive is embedded on the carrier, the generated embedded scratch is shallow, and the scratch problem caused by abrasive aggregation and abrasive disc surface embedding can be solved. The fixed abrasive material is used for grinding, so that the high points on the surface of the wafer can be effectively removed, the grinding wheel is not easy to deform, and the processed surface type parameters are good, so that the flatness of the wafer is improved.
2. The single crystal silicon carbide substrate is processed by adopting the grinding wheel to solidify the grinding material, and the obtained single crystal silicon carbide substrate has better surface type data and lower total thickness change, local thickness change, curvature and warping degree.
3. The invention adopts an acid CMP processing method, can quickly and effectively remove the damage caused by the Grinding process, improves the efficiency by 5-10 times, and can ensure that the surface roughness of the wafer is less than or equal to 0.2 nm. The substrate prepared by the invention has no subsurface damage layer.
4. The processing method of the single crystal silicon carbide substrate is suitable for processing substrates of 2 inches, 3 inches, 4 inches, 6 inches and 8 inches, and the larger the size of the substrate is, the more obvious the advantages are.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and not to limit the invention. In the drawings:
FIG. 1 is an AFM surface topography of a single crystal silicon carbide substrate made by conventional processing methods
FIG. 2 is an AFM surface topography of a single crystal silicon carbide substrate made by the method of the present invention
FIG. 3 is a flow chart of a method for preparing a high-flatness low-damage silicon carbide single crystal substrate according to the present invention
Detailed Description
In order to more clearly explain the overall concept of the invention, the following detailed description is given by way of example in conjunction with the accompanying drawings.
A method for preparing a high-flatness low-damage single-crystal silicon carbide substrate, the flow of the preparation method is shown in figure 3, and the preparation method comprises the following steps:
step 2, diamond wire cutting: cutting the single crystal silicon carbide primarily processed in the step 1 by using a diamond wire, wherein the tension of the cutting wire is 22-40N, the linear running speed is 1200-1800m/min, the swing angle is 1-10 degrees, the feed speed is 5-15mm/h, and the diameter of the diamond wire is 0.12-0.28 mm;
step 3, grinding by using a grinding wheel: respectively installing Grinding wheels with two meshes in two stations of Grinding equipment, and Grinding the single crystal silicon carbide cut by the diamond wire in the step 2 as coarse Grinding and fine Grinding, wherein the Grinding wheels with 1000-5000 meshes are used for coarse Grinding, and the rotating speed and the feed speed are used for coarse Grinding; the grinding wheel with 20000 meshes to 30000 meshes is used for fine grinding, the rotating speed is 1000-2000rpm, and the feed speed is 0.2-1 um/s;
step 4, acid CMP processing: using acidic chemical mechanical polishing solution to perform acidic CMP processing on the monocrystalline silicon carbide ground by the grinding wheel in the step 3, wherein the pH value is kept to be 2-4, the rotating speed is 20-50rpm, and the pressure is 200-2The material flow is 3-10L/min.
Example 1
A method of preparing a high flatness, low damage single crystal silicon carbide substrate having a diameter of 100mm, the method comprising:
step 2, diamond wire cutting: cutting the single crystal silicon carbide primarily processed in the step 1 by using a diamond wire, wherein the tension of a cutting wire is 22N, the linear running speed is 1200m/min, the swing angle is 5 degrees, the feed speed is 5mm/h, and the diameter of the diamond wire is 0.12 mm;
step 3, grinding by using a grinding wheel: respectively installing Grinding wheels with two meshes in two stations of Grinding equipment, and Grinding the single crystal silicon carbide cut by the diamond wire in the step 2 as coarse Grinding and fine Grinding, wherein the Grinding wheel with 1000 meshes is used for coarse Grinding, and the rotating speed and the feed speed are used for coarse Grinding; the 20000-mesh grinding wheel is used for fine grinding, the rotating speed is 1000rpm, and the feed speed is 0.2 um/s;
step 4, acid CMP processing: performing acid CMP processing on the monocrystalline silicon carbide ground by the grinding wheel in the step 3 by using acid chemical mechanical polishing solution, wherein the pH value is kept to be 2, the rotating speed is 20rpm, and the pressure is 200g/cm in the acid CMP processing process2The material flow is 5L/min.
The single crystal silicon carbide substrate having a diameter of 100mm obtained in example 1 had the following technical parameters:
surface roughness of 0.05nm, no subsurface damage layer, small scratch die ratio of 5%, pit ratio of 0.05/cm2The bump ratio is 0.05 pieces/cm2。
The surface type data is as follows: TTV 2um, LTV (1 cm x 1 cm) 1.5um, Bow 15um, Warp 30 um.
Example 2
A method of preparing a high flatness, low damage single crystal silicon carbide substrate having a diameter of 100mm, the method comprising:
step 2, diamond wire cutting: cutting the single crystal silicon carbide primarily processed in the step 1 by using a diamond wire, wherein the tension of a cutting wire is 40N, the linear running speed is 1800m/min, the swing angle is 10 degrees, the feed speed is 15mm/h, and the diameter of the diamond wire is 0.28 mm;
step 3, grinding by using a grinding wheel: respectively installing Grinding wheels with two meshes in two stations of Grinding equipment, and Grinding the single crystal silicon carbide cut by the diamond wire in the step 2 as coarse Grinding and fine Grinding, wherein the Grinding wheel with 5000 meshes is used for coarse Grinding, and the rotating speed and the feed speed are used for coarse Grinding; a 30000-mesh grinding wheel is used for fine grinding, the rotating speed is 2000rpm, and the feed speed is 1 um/s;
step 4, acid CMP processing: performing acid CMP processing on the monocrystalline silicon carbide ground by the grinding wheel in the step 3 by using acid chemical mechanical polishing solution, wherein the pH value is kept at 4, the rotating speed is 50rpm, and the pressure is 500g/cm in the acid CMP processing process2The material flow is 5L/min.
The single crystal silicon carbide substrate having a diameter of 100mm obtained in example 2 had the following technical parameters:
the surface roughness is 0.08nm, no subsurface damage layer exists, the proportion of fine scratches is 4 percent, and the proportion of pit is 0.03/cm2The bump ratio is 0.03 pieces/cm2。
The surface type data is as follows: TTV 1.5um, LTV (1 cm x 1 cm) 1.1um, Bow 10um, Warp 20 um.
Example 3
A method of preparing a high flatness, low damage single crystal silicon carbide substrate having a diameter of 150mm, the method comprising:
step 2, diamond wire cutting: cutting the single crystal silicon carbide primarily processed in the step 1 by using a diamond wire, wherein the tension of a cutting wire is 30N, the linear running speed is 1500m/min, the swing angle is 5 degrees, the feed speed is 10mm/h, and the diameter of the diamond wire is 0.15 mm;
step 3, grinding by using a grinding wheel: respectively installing Grinding wheels with two meshes in two stations of Grinding equipment, and Grinding the single crystal silicon carbide cut by the diamond wire in the step 2 as coarse Grinding and fine Grinding, wherein the 3000-mesh Grinding wheel is used for coarse Grinding, and the rotating speed and the feed speed are used for coarse Grinding; a 25000-mesh grinding wheel is used for fine grinding, the rotating speed is 1500rpm, and the feed speed is 0.5 um/s;
step 4, acid CMP processing: performing acid CMP processing on the monocrystalline silicon carbide ground by the grinding wheel in the step 3 by using acid chemical mechanical polishing solution, wherein the pH value is kept to be 3, the rotating speed is 30rpm, and the pressure is 300g/cm in the acid CMP processing process2And the material flow is 8L/min.
The single crystal silicon carbide substrate having a diameter of 150mm obtained in example 3 had the following technical parameters:
the surface roughness is 0.08nm, no subsurface damage layer exists, the proportion of fine scratches is 6 percent, and the proportion of pit is 0.06 per cm2The bump ratio is 0.05 pieces/cm2。
The surface type data is as follows: TTV 3um, LTV (1 cm x 1 cm) 1.8um, Bow 17um, Warp 25 um.
Example 4
A method of preparing a high flatness, low damage single crystal silicon carbide substrate having a diameter of 150mm, the method comprising:
step 2, diamond wire cutting: cutting the single crystal silicon carbide primarily processed in the step 1 by using a diamond wire, wherein the tension of a cutting wire is 35N, the linear running speed is 1600m/min, the swing angle is 5 degrees, the feed speed is 12mm/h, and the diameter of the diamond wire is 0.15 mm;
step 3, grinding by using a grinding wheel: respectively installing Grinding wheels with two meshes in two stations of Grinding equipment, and Grinding the single crystal silicon carbide cut by the diamond wire in the step 2 as coarse Grinding and fine Grinding, wherein the 3000-mesh Grinding wheel is used for coarse Grinding, and the rotating speed and the feed speed are used for coarse Grinding; a 25000-mesh grinding wheel is used for fine grinding, the rotating speed is 1500rpm, and the feed speed is 0.6 um/s;
step 4, acid CMP processing: performing acid CMP processing on the monocrystalline silicon carbide ground by the grinding wheel in the step 3 by using acid chemical mechanical polishing solution, wherein the pH value is kept to be 2.5, the rotating speed is 40rpm, and the pressure is 400g/cm in the acid CMP processing process2The flow rate was 6L/min.
The single crystal silicon carbide substrate having a diameter of 150mm obtained in example 4 had the following technical parameters:
surface roughness of 0.01nm, no subsurface damage layer, small scratch die ratio of 5%, pit ratio of 0.03/cm2The bump ratio is 0.03 pieces/cm2。
The surface type data is as follows: TTV 1.4um, LTV (1 cm x 1 cm) 0.9um, Bow 9um, Warp 16 um.
Example 5
A method of producing a high flatness, low damage single crystal silicon carbide substrate having a diameter of 200mm, the method comprising:
step 2, diamond wire cutting: cutting the single crystal silicon carbide primarily processed in the step 1 by using a diamond wire, wherein the tension of a cutting wire is 35N, the linear running speed is 1500m/min, the swing angle is 4 degrees, the feed speed is 10mm/h, and the diameter of the diamond wire is 0.154 mm;
step 3, grinding by using a grinding wheel: respectively installing Grinding wheels with two meshes in two stations of Grinding equipment, and Grinding the single crystal silicon carbide cut by the diamond wire in the step 2 as coarse Grinding and fine Grinding, wherein the 3000-mesh Grinding wheel is used for coarse Grinding, and the rotating speed and the feed speed are used for coarse Grinding; a 25000-mesh grinding wheel is used for fine grinding, the rotating speed is 1500rpm, and the feed speed is 0.6 um/s;
step 4, acid CMP processing: performing acid CMP processing on the monocrystalline silicon carbide ground by the grinding wheel in the step 3 by using acid chemical mechanical polishing liquid, wherein the pH value is kept to be 2, the rotating speed is 35rpm, and the pressure is 400g/cm in the acid CMP processing process2And the material flow is 8L/min.
The single crystal silicon carbide substrate having a diameter of 200mm obtained in example 5 had the following technical parameters:
surface roughness of 0.01nm, no subsurface damage layer, a proportion of fine scratches die of 9% and a proportion of pit of 0.03/cm2The bump ratio is 0.02 pieces/cm2。
The surface type data is as follows: TTV 3.5um, LTV (1 cm x 1 cm) 2.3um, Bow 24um, Warp 35 um.
Comparative example 1
Fig. 1 shows a surface 10um x 10um AFM topography of a single crystal silicon carbide substrate prepared by a conventional processing method, and the obtained substrate has a surface with more scratches and a larger roughness and a damaged layer on the surface as seen from the AFM topography. FIG. 2 shows a 10um by 10um AFM surface topography of the surface of a single crystal silicon carbide substrate prepared by the method of the present invention, and from the AFM surface topography, the surface of the obtained substrate has almost no scratch, good surface uniformity, low roughness and no damage layer on the surface.
Comparative example 2
The surface roughness and the tool mark rate of a cutting piece obtained by adding and not adding an abrasive material in cooling liquid in the diamond wire cutting process are tested. The test result shows that the cooling liquid is not added with abrasive, the surface roughness of the cutting piece is not 500-700nm, and the rate of the tool mark is 5-10%; after the abrasive is added into the cooling liquid, the surface roughness of the cutting piece is 200-400nm, and the rate of the tool mark is less than 5 percent.
The cutting rate of diamond wire cutting is improved by 5-10 times than that of sand wire cutting.
Those not described in detail in this specification are within the skill of the art. The above description is only an example of the present invention, and is not intended to limit the present invention. Various modifications and alterations to this invention will become apparent to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.
Claims (12)
1. A method for rapidly preparing a high-flatness low-damage monocrystalline silicon carbide substrate suitable for an 8-inch monocrystalline silicon carbide substrate, the method comprising the steps of:
carrying out full-consolidation abrasive processing on the monocrystalline silicon carbide, and then carrying out chemical mechanical polishing treatment to obtain the monocrystalline silicon carbide substrate with high flatness and low damage;
wherein the fully consolidated abrasive machining includes wire cutting and wheel grinding, and abrasive grains are consolidated on the cutting wire for wire cutting and abrasive grains are consolidated on the wheel for wheel grinding;
the thickness of the single crystal silicon carbide substrate is less than 200um, and the surface type data of the single crystal silicon carbide substrate are as follows: the total thickness change is less than 10um, the local thickness change is less than 2um, the bending degree is less than 50um, and the warping degree is less than 70um, wherein the local thickness change refers to the thickness change of a 1 cm-1 cm area of the surface of the single crystal silicon carbide substrate.
2. The method of claim 1, wherein the rapid manufacturing process for a high flatness, low damage single crystal silicon carbide substrate suitable for an 8-inch single crystal silicon carbide substrate,
the surface roughness of the single crystal silicon carbide substrate is less than or equal to 0.10nm, the ratio of unqualified blocks of fine scratches is less than 10 percent, and the ratio of pits is less than 0.1/cm2The ratio of the protrusions is less than 0.1/cm2。
3. The method of claim 1, wherein the rapid manufacturing process for a high flatness, low damage single crystal silicon carbide substrate suitable for an 8-inch single crystal silicon carbide substrate,
the wire cutting is specifically diamond wire cutting, wherein abrasive particles with the mass percentage concentration of 2-10% are added into cooling liquid used in the diamond wire cutting process;
the abrasive particles used in the cooling liquid are selected from one or more of alumina, diamond and boron carbide, and the particle size of the abrasive particles is 50-100 nm.
4. The method of claim 3, wherein the rapid manufacturing process for a high flatness, low damage single crystal silicon carbide substrate suitable for an 8-inch single crystal silicon carbide substrate,
the diamond wire cutting processing step has the cutting wire tension of 22-40N, the wire running speed of 1200-1800m/min, the swing angle of 1-10 degrees, the feed speed of 5-15mm/h and the diamond wire diameter of 0.12-0.28 mm.
5. The method of claim 4, wherein the single-crystal silicon carbide substrate is a high-flatness, low-damage single-crystal silicon carbide substrate having a high flatness and a low damage,
the diamond wire cutting processing step has the cutting wire tension of 30-40N, the wire running speed of 1300-1600m/min, the swing angle of 3-8 degrees, the feed speed of 8-12mm/h and the diamond wire diameter of 0.15-0.20 mm.
6. The method of claim 1, wherein the rapid manufacturing process for a high flatness, low damage single crystal silicon carbide substrate suitable for an 8-inch single crystal silicon carbide substrate,
the grinding of the grinding wheel comprises two steps of coarse grinding and fine grinding;
wherein, the consolidated abrasive in the rough grinding is obtained by consolidating abrasive grains of 1000 meshes to 5000 meshes on a grinding wheel;
the fixed abrasive in the fine grinding is formed by fixing abrasive particles of 20000 meshes to 30000 meshes on a grinding wheel.
7. The method of claim 6, wherein the rapid manufacturing process for a high flatness, low damage single crystal silicon carbide substrate suitable for an 8-inch single crystal silicon carbide substrate,
the rotation speed of the grinding wheel in the coarse grinding step is 1000-2000rpm, and the feed speed is 0.2-1 um/s; the rotation speed of the grinding wheel in the fine grinding step is 1000-.
8. The method of claim 1, wherein the rapid manufacturing process for a high flatness, low damage single crystal silicon carbide substrate suitable for an 8-inch single crystal silicon carbide substrate,
the chemical mechanical polishing is acid chemical mechanical polishing.
9. The method of claim 8, wherein the rapid manufacturing process for a high flatness, low damage single crystal silicon carbide substrate suitable for an 8-inch single crystal silicon carbide substrate,
the polishing solution used in the step of acidic chemical mechanical polishing treatment comprises: abrasive, oxidant, water-soluble acidic polymer, dispersant and purified water;
wherein, the mass percentage concentration of the grinding material is 1-30%;
the abrasive is selected from one or more of silicon oxide, aluminum oxide, diamond particles, cerium oxide, silicon carbide, boron carbide, zirconium oxide and diamond;
the oxidant is selected from one or more of hydrogen peroxide, potassium permanganate, nitric acid, hydrochloric acid and potassium perchlorate;
the water-soluble acidic polymer is selected from one or more of carboxyl polymer and sulfonic polymer;
the dispersing agent is selected from one or more of higher alcohol, polyvinyl alcohol and polyethylene glycol, and the mass percentage concentration of the dispersing agent is 0.2-1%.
10. The method of claim 9, wherein the rapid manufacturing process for a high flatness, low damage single crystal silicon carbide substrate suitable for an 8-inch single crystal silicon carbide substrate,
the pH value of the acidic chemical mechanical polishing solution in the acidic chemical mechanical polishing treatment step is 2-4, the rotating speed is 20-50rpm, and the pressure is 200-2The material flow is 3-10L/min.
11. The method of claim 1, wherein the rapid manufacturing process for a high flatness, low damage single crystal silicon carbide substrate suitable for an 8-inch single crystal silicon carbide substrate,
the single crystal silicon carbide is also subjected to primary processing before diamond wire cutting, wherein the primary processing adopts a fixed abrasive processing mode.
12. The method of claim 1, wherein the rapid manufacturing process for a high flatness, low damage single crystal silicon carbide substrate suitable for an 8-inch single crystal silicon carbide substrate,
the abrasive particles are selected from one or more of silicon oxide, aluminum oxide, cerium oxide, silicon carbide, boron carbide, zirconium oxide and diamond.
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| CN201811205285.7A CN109545680B (en) | 2018-10-16 | 2018-10-16 | Rapid preparation method of high-flatness and low-damage monocrystalline silicon carbide substrate |
| KR1020217027445A KR102471865B1 (en) | 2018-10-16 | 2018-12-26 | High-flatness, low-damage and large-diameter monocrystalline silicon carbide substrate, and manufacturing method therefor |
| KR1020197037367A KR20200044726A (en) | 2018-10-16 | 2018-12-26 | Single crystal silicon carbide substrate with high flatness and low damage and its manufacturing method |
| PCT/CN2018/123718 WO2020077849A1 (en) | 2018-10-16 | 2018-12-26 | High-flatness, low-damage and large-diameter monocrystalline silicon carbide substrate, and manufacturing method therefor |
| JP2019571534A JP7298915B2 (en) | 2018-10-16 | 2018-12-26 | Method for manufacturing single-crystal silicon carbide substrate |
| EP18922088.2A EP3666937B1 (en) | 2018-10-16 | 2018-12-26 | High-flatness, low-damage and large-diameter monocrystalline silicon carbide substrate, and manufacturing method therefor |
| TW108136950A TWI748260B (en) | 2018-10-16 | 2019-10-14 | High-flatness, low-damage large-diameter single crystal silicon carbide substrate and preparation method thereof |
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| CN110539240A (en) * | 2019-07-18 | 2019-12-06 | 浙江博蓝特半导体科技股份有限公司 | Processing method of silicon carbide single crystal substrate |
| CN111755321A (en) * | 2020-05-20 | 2020-10-09 | 嘉兴市轩禾园艺技术有限公司 | Preparation method of polycrystalline silicon semiconductor film substrate |
| CN112209380A (en) * | 2020-10-13 | 2021-01-12 | 哈尔滨科友半导体产业装备与技术研究院有限公司 | Method for recovering silicon carbide crystal mortar linear cutting waste liquid |
| CN114686113A (en) * | 2020-12-30 | 2022-07-01 | 安集微电子科技（上海）股份有限公司 | Chemical mechanical polishing solution and using method thereof |
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| CN113752403A (en) * | 2021-09-17 | 2021-12-07 | 宁波江丰电子材料股份有限公司 | Silicon carbide target material assembly and preparation method thereof |
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