Laser modification and polishing integrated method for improving semiconductor wafer thinning efficiency

Abstract

The invention discloses a laser modification and polishing integrated method for improving the thinning efficiency of a semiconductor wafer. The method comprises the following steps: firstly, placing a wafer on an ultrasonic vibration platform; then laser low-speed scanning parameters are set, so that the semiconductor wafer is efficiently modified under the action of ultrasonic vibration; then an airflow device is started, laser polishing parameters are set, and the laser polishes the surface of the modified wafer under the action of ultrasonic vibration and high-speed airflow; and finally, a wafer thinning machine matched with a fine-particle-size diamond grinding wheel is used for carrying out grinding and thinning on the wafer subjected to laser polishing, so that a final finished product sample piece is obtained. The method has the advantages of being simple, efficient, high in repeatability and the like, and the thinning efficiency can be effectively improved and the wafer thinning cost can be effectively reduced in combination with the external field-assisted laser modification polishing process.

Description

Technical Field

[0001] The invention belongs to the technical field of laser-assisted processing, and in particular relates to an integrated laser modification and polishing method for improving semiconductor wafer thinning efficiency. Background Art

[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 their high hardness and brittleness, the thinning and polishing processes of such materials face many technical challenges. Traditional mechanical processing methods, such as grinding wheel thinning and chemical mechanical polishing, usually have problems such as low efficiency, high processing costs and difficult to ensure surface quality. In addition, multiple processing steps not only increase equipment investment and maintenance costs, but may also introduce more processing defects.

[0003] In the prior art, although the laser modification process has improved the efficiency and surface quality of the semiconductor wafer thinning process to a certain extent, there are still some shortcomings. In particular, for the fine processing of the wafer surface, how to further improve the processing efficiency, reduce costs and improve the surface quality is still a key issue that needs to be solved. Therefore, a new processing method is needed to improve the efficiency and surface quality of the semiconductor wafer thinning process. In response to the above problems, this paper proposes an integrated laser modification and polishing method, which is expected to achieve efficient and high-quality thinning processing of semiconductor wafers. Summary of the invention

[0004] (I) Purpose of the invention

[0005] In view of the deficiencies in the prior art, the object of the present invention is to provide an integrated laser modification and polishing method for improving the efficiency of semiconductor wafer thinning, aiming to improve the efficiency and quality of the wafer thinning process.

[0006] (II) Technical solution

[0007] The present invention is achieved through the following technical solutions.

[0008] (1) Pre-treating the surface of the semiconductor wafer obtained by multi-wire cutting or laser stripping to remove surface dirt and improve surface finish;

[0009] (2) placing the cleaned and dried wafer on an ultrasonic vibration device and setting ultrasonic vibration parameters;

[0010] (3) turning on the femtosecond laser, setting slow scanning modified laser parameters, and starting to process the semiconductor wafer;

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

[0012] (5) turning on the femtosecond laser, setting the laser polishing parameters, setting the scanning path, and starting to polish the modified semiconductor wafer;

[0013] (6) The semiconductor wafer that has been laser polished is thinned and ground using a fine-grained diamond grinding wheel to obtain a final finished product sample.

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

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

[0016] Furthermore, the airflow parameters in step (4) include airflow rate, airflow direction and airflow type, wherein the airflow rate is 10-30 m / 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 spacing, and scanning times, and their values ​​are set to 50fs-300fs, 343 or 532nm, 8W-12W, 100KHz-1 MHz, 100mm / s-1000mm / s, 5-30μm, and 2-5 times, respectively;

[0018] Furthermore, the laser polishing path in step (5) is a cross-scanning method.

[0019] (III) Beneficial effects

[0020] The above technical solution of the present invention has the following beneficial technical effects:

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

[0022] (2) The laser polishing process proposed in the present invention can efficiently remove the oxide deposition layer produced by the laser slow scanning modification process on the basis of the laser modified surface, and optimize the surface quality, thereby eliminating the original rough grinding process.

[0023] (3) The airflow-assisted process proposed in the present invention can effectively reduce and blow away the oxide deposition layer during the laser modification and polishing process, thereby improving the processing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of a method and device for processing semiconductor wafers according to the present invention.

[0025] Figure 2 It is a schematic diagram of the process flow of semiconductor wafer processing according to the present invention.

[0026] Figure 3 This is a comparison chart of the surface roughness of the modified wafer obtained in Example 1 and the original silicon carbide wafer. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the present invention more clear, the present invention is further described in detail below in combination with specific implementation methods and with reference to the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention.

[0028] Embodiment 1:

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

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

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

[0032] (4) After the laser modification is completed, the airflow device is turned on and the airflow parameters are set, including the airflow rate, airflow direction and airflow type. 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, set the laser polishing parameters, laser pulse width, laser wavelength, laser power, pulse frequency, scanning speed, scanning spacing, and scanning times, and set the 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 laser-polished silicon carbide wafer is thinned and ground with fine-grained diamond to obtain the final finished product sample.

[0035] Test results: Figure 3 This is a comparison chart of the surface roughness of the modified polished surface of the wafer obtained in Example 1 and the original silicon carbide wafer. It can be found that the surface roughness after laser modification and polishing is greatly reduced compared with the original cut wafer.

[0036] It should be understood that the above specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, and do not constitute a limitation of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the appended claims, or the equivalent forms of such scope and boundaries.

Claims

1. A laser modification and polishing integrated method for improving semiconductor wafer thinning efficiency, characterized in that The steps include: (1) Pre-treating the surface of the semiconductor wafer obtained by multi-wire cutting or laser stripping to remove surface dirt and improve surface finish; (2) placing the cleaned and dried wafer on an ultrasonic vibration device and setting ultrasonic vibration parameters; (3) turning on the femtosecond laser, setting slow scanning modified laser parameters, and starting to process the semiconductor wafer; (4) After laser modification is completed, turn on the airflow device and set the airflow parameters; (5) turning on the femtosecond laser, setting the laser polishing parameters, setting the scanning path, and starting to polish the modified semiconductor wafer; (6) The semiconductor wafer that has been laser polished is thinned and ground using a diamond grinding wheel, and the final finished product sample is obtained after grinding.

2. The laser modification and polishing integrated method for improving semiconductor wafer thinning efficiency according to claim 1, characterized in that: The ultrasonic vibration parameters in step (2) include vibration frequency, vibration intensity and amplitude, and their values ​​are set to 20-40KHz, 20-50W, and 10μm respectively.

3. The laser modification and polishing integrated method for improving semiconductor wafer thinning efficiency according to claim 1, characterized in that: The slow scanning modified laser parameters in the step (3) include laser pulse width, laser wavelength, laser power, pulse frequency, scanning speed, scanning spacing, and scanning times, and their values ​​are set to 50fs-300fs, 1026nm, 4W-8W, 100KHz-1 MHz, 5mm / s-20mm / s, 10-20μm, and 2-10 times, respectively.

4. The laser modification and polishing integrated method for improving semiconductor wafer thinning efficiency according to claim 1, characterized in that: The airflow parameters in step (4) include airflow rate, airflow direction and airflow type, wherein the airflow rate is 10-30 m / s, the airflow direction is consistent with the laser scanning direction, and the airflow type is one of nitrogen or helium.

5. The laser modification and polishing integrated method for improving semiconductor wafer thinning efficiency according to claim 1, characterized in that: The laser polishing parameters in step (5) include laser pulse width, laser wavelength, laser power, pulse frequency, scanning speed, scanning spacing, and scanning times, and their values ​​are set to 50fs-300fs, 343 or 532nm, 8W-12W, 100KHz-1 MHz, 100mm / s-1000mm / s, 5-30μm, and 2-5 times, respectively.

6. The integrated laser modification and polishing method for improving silicon carbide thinning efficiency according to claim 1, characterized in that: The laser polishing path in step (5) is a cross-scanning method.

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