A laser modification polishing integrated method for improving thinning efficiency of silicon carbide wafer

Abstract

The application discloses a laser modification polishing integrated method for improving thinning efficiency of silicon carbide wafers. First, the wafer is placed on an ultrasonic vibration platform; then laser slow scanning parameters are set to make the semiconductor wafer efficiently modified under the action of ultrasonic vibration; then an air flow device is started, laser polishing parameters are set, and the laser is polished on the surface of the modified wafer under the action of ultrasonic vibration and high-speed air flow; finally, the wafer after laser polishing is ground and thinned by a wafer thinning machine matched with a fine-grit diamond grinding wheel, so that the final finished product sample is obtained. The method has the advantages of simplicity, high efficiency, strong repeatability and the like, and in combination with an external field assisted laser modification polishing process, the thinning efficiency can be effectively improved and the wafer thinning cost can be reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of laser-assisted processing, and particularly relates to a laser modification and polishing integrated method for improving the thinning efficiency of a silicon carbide wafer. BACKGROUND

[0002] Semiconductor materials such as silicon carbide have high hardness, high thermal conductivity and good chemical stability, and have been widely used in the manufacture of high-power and high-frequency electronic devices. However, due to its high hardness and brittleness, the thinning and polishing process of such materials faces many technical challenges. Traditional mechanical processing methods, such as abrasive wheel thinning and chemical mechanical polishing, usually have problems such as low efficiency, high processing cost and difficult to guarantee surface quality. In addition, multiple processing steps not only increase equipment investment and maintenance cost, but also may introduce more processing defects.

[0003] In the prior art, although the laser modification process improves the efficiency and surface quality of the semiconductor wafer thinning process to some extent, there are still some deficiencies. In particular, for the fine processing of the wafer surface, how to further improve the processing efficiency, reduce the cost and improve the surface quality is still a key problem to be solved. Therefore, a new processing method is needed to improve the efficiency and surface quality of the semiconductor wafer thinning process. In view of the above problems, the present application proposes a laser modification and polishing integrated method, which is expected to realize high-efficiency and high-quality thinning processing of semiconductor wafers. SUMMARY

[0004] (I) Invention purpose

[0005] In view of the deficiencies of the prior art, the purpose of the present application is to provide a laser modification and polishing integrated method for improving the thinning efficiency of a silicon carbide wafer, aiming to improve the efficiency and quality in the wafer thinning process.

[0006] (II) Technical solution

[0007] The present application is realized by the following technical solutions.

[0008] (1) The semiconductor wafer obtained by multi-wire cutting or laser stripping is subjected to surface pretreatment to remove surface contaminants and improve surface smoothness;

[0009] (2) The cleaned and dried wafer is placed on an ultrasonic vibration device, and the ultrasonic vibration parameters are set;

[0010] (3) Turn on the femtosecond laser, set the slow scanning modification laser parameters, and start processing the semiconductor wafer;

[0011] (4) After laser modification, turn on the airflow device and set the airflow parameters.

[0012] (5) Turn on the femtosecond laser, set the laser polishing parameters, set the scanning path, and start polishing the modified semiconductor wafer;

[0013] (6) The semiconductor wafer polished by laser is thinned by fine-grit diamond grinding wheel, and the final product sample is obtained after grinding.

[0014] Further, the ultrasonic vibration parameters in step (2) include vibration frequency, vibration intensity and amplitude, and their values are respectively set to 20-40KHz, 20-50W and 10μm;

[0015] Further, the slow scanning modification laser parameters in step (3) include laser pulse width, laser wavelength, laser power, pulse frequency, scanning speed, scanning interval, and scanning times, and their values are respectively set to 50fs-300fs, 1026nm, 4W-8W, 100KHz-1 MHz, 5mm / s-20mm / s, 10-20μm, and 2-10 times;

[0016] Further, the airflow parameters in step (4) include airflow rate, airflow direction and airflow type, wherein the airflow rate is 10-30m / s, the airflow direction is consistent with the laser scanning direction, and the airflow type is one of nitrogen or helium;

[0017] Further, the laser polishing parameters in step (5) include laser pulse width, laser wavelength, laser power, pulse frequency, scanning speed, scanning interval, and scanning times, and their values are respectively set to 50fs-300fs, 343 or 532nm, 8W-12W, 100KHz-1 MHz, 100mm / s-1000mm / s, 5-30μm, and 2-5 times;

[0018] Further, the laser polishing path in step (5) is a cross scanning mode.

[0019] (Three) Beneficial effects

[0020] The above technical scheme of the present application has the following beneficial technical effects:

[0021] (1) The ultrasonic vibration assisted process proposed in the present application can effectively increase the efficiency and quality of the laser modification and polishing process.

[0022] (2) The laser polishing process proposed in the present application can efficiently remove the oxidation deposition layer generated in the laser slow scanning modification process on the basis of the laser modified surface, and optimize the surface quality, which can save the original rough grinding process.

[0023] (3) The airflow auxiliary process can effectively reduce and blow off the oxidized deposition layer in the laser modification and polishing process, and improve the processing efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 A schematic diagram of a method and device for processing a semiconductor wafer.

[0025] Figure 2 A schematic diagram of a process flow for processing a semiconductor wafer.

[0026] Figure 3 A comparison diagram of the roughness of the modified surface of the wafer obtained in Example 1 and the original silicon carbide wafer surface. DETAILED DESCRIPTION

[0027] To make the purpose, technical scheme and advantages of the present application clearer and more comprehensible, the present application will be further described in detail below with reference to the specific embodiments and the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present application.

[0028] Example 1:

[0029] (1) The silicon carbide wafer obtained by multi-wire cutting or laser stripping is pretreated to remove surface contaminants and improve surface smoothness.

[0030] (2) The cleaned and dried wafer is placed on an ultrasonic vibration device, and the ultrasonic vibration parameters, including vibration frequency, vibration intensity and amplitude, are set to 20 KHz, 20 W and 10 μm, respectively.

[0031] (3) Turn on the femtosecond laser, set the slow scanning modification laser parameters, including laser pulse width, laser wavelength, laser power, pulse frequency, scanning speed, scanning pitch, scanning times, and set their values to 230 fs, 1026 nm, 6 W, 100 KHz, 5 mm / s, 10 μm, 2 times, respectively, and start processing the silicon carbide wafer.

[0032] (4) After the laser modification is completed, turn on the airflow device and set the airflow parameters, including airflow rate, airflow direction and airflow type, wherein the airflow rate is 30 m / s, the airflow direction is consistent with the laser scanning direction, and the airflow type is nitrogen.

[0033] (5) Turn on the femtosecond laser and set the laser polishing parameters, including laser pulse width, laser wavelength, laser power, pulse frequency, scanning speed, scanning pitch, and scanning times, and set their values to 100 fs, 343 nm, 10 W, 100 KHz, 500 mm / s, 10 μm, and 5 times, respectively, set the cross scanning path, and start polishing the modified silicon carbide wafer;

[0034] (6) The silicon carbide wafer polished by laser is thinned by fine-grit diamond, and the final product sample is obtained after grinding.

[0035] Test results: Figure 3 The roughness of the modified polishing surface of the wafer obtained in Example 1 is compared with that of the original silicon carbide wafer surface, and it can be found that the roughness of the surface after laser modification and polishing is greatly reduced compared with that of the original cutting piece.

[0036] It should be understood that the above specific embodiments of the present application are only used for illustrative or explanatory purposes of the principles of the present application, and do not constitute a limitation on the present application. Therefore, any modification, equivalent replacement, improvement, etc. made without departing from the spirit and scope of the present application shall be included in the protection scope of the present application. In addition, the appended claims of the present application are intended to cover all variations and modifications falling within the scope and boundary of the appended claims, or the equivalent forms of such scope and boundary.

Claims

1. A method for improving the thinning efficiency of a silicon carbide wafer by integrating laser modification and polishing, characterized in that It comprises the following steps: (1) The semiconductor wafer obtained by multi-wire cutting or laser stripping is pretreated on the surface to remove surface dirt and improve surface finish; (2) The cleaned and dried wafer is placed on an ultrasonic vibration device, and the ultrasonic vibration parameters are set; (3) Turn on the femtosecond laser, set the slow scanning modification laser parameters, and start processing the semiconductor wafer; (4) After laser modification, turn on the airflow device and set the airflow parameters; (5) Turn on the femtosecond laser, set the laser polishing parameters, set the scanning path, and start polishing the modified semiconductor wafer to efficiently remove the oxidation deposition layer generated during the slow scanning modification process on the basis of the laser modified surface; (6) The semiconductor wafer polished by laser is thinned and ground by a diamond fine grinding wheel, and the final product sample is obtained after grinding.

2. The method of claim 1, wherein the method further comprises: The ultrasonic vibration parameters in step (2) include vibration frequency, vibration intensity and amplitude, which are set to 20KHz-40KHz, 20W-50W and 10μm respectively.

3. The method of claim 1, wherein the method further comprises: The slow scanning modification laser parameters in step (3) include laser pulse width, laser wavelength, laser power, pulse frequency, scanning speed, scanning pitch and scanning times, which are set to 50fs-300fs, 1026nm, 4W-8W, 100KHz-1MHz, 5mm / s-20mm / s, 10μm-20μm and 2-10 times respectively.

4. The method of claim 1, wherein the method further comprises: The airflow parameters in step (4) include airflow rate, airflow direction and airflow type, wherein the airflow rate is 10m / s-30m / s, the airflow direction is consistent with the laser scanning direction, and the airflow type is one of nitrogen or helium.

5. The method of claim 1, wherein the method further comprises: The laser polishing parameters in step (5) include laser pulse width, laser wavelength, laser power, pulse frequency, scanning speed, scanning pitch and scanning times, which are set to 50fs-300fs, 343nm or 532nm, 8W-12W, 100KHz-1MHz, 100mm / s-1000mm / s, 5μm-30μm, 2-5 times respectively.

6. The method of claim 1, wherein the method further comprises: The laser polishing path in step (5) is a cross scanning mode.

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