Method for improving semiconductor wafer thinning efficiency through temperature and atmosphere coordinated regulation and control

Abstract

The invention discloses a method for improving semiconductor wafer thinning efficiency through temperature and atmosphere coordinated regulation and control. The method comprises the following steps: placing a wafer in a low-temperature modification environment; then, the oxygen concentration of the modified environment is always kept constant through a dynamic oxygen concentration adjusting device; then laser parameters are adjusted, so that the semiconductor wafer is subjected to high-efficiency and high-quality modification in a low-temperature oxygen-enriched environment; and finally, grinding and thinning the modified wafer through a wafer thinning machine so as to obtain a final finished product sample piece. The method has the advantages of being simple, efficient, high in repeatability and the like, the advantages of laser modification in the low-temperature and oxygen-enriched environments are combined, and the laser modification efficiency and quality can be effectively improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser-assisted processing, and in particular relates to a method for improving semiconductor wafer thinning efficiency by coordinated regulation of temperature and atmosphere. Background Art

[0002] Semiconductors such as silicon carbide are widely used in the manufacture of semiconductor devices and power electronic devices due to their excellent mechanical strength, high thermal conductivity, high temperature resistance and corrosion resistance. However, these semiconductors are hard and brittle, which leads to low efficiency, poor surface quality and high material loss during mechanical thinning and grinding.

[0003] Due to its ultra-short pulse time and ultra-high energy density, pulse laser can form a modified layer and micro-nano structure on the surface while removing a certain depth of material, thereby improving the machinability of silicon carbide materials. However, the composition and uniformity of the modified layer after pulse laser modification greatly affect the efficiency and surface quality of subsequent mechanical thinning. The existing technology has limited control capabilities in the above aspects, especially the regulation of changes in the chemical environment of the material surface.

[0004] The present invention significantly optimizes the composition, uniformity and sub-surface quality of the modified layer of the semiconductor wafer by synergistically regulating the modification temperature and atmosphere and combining the pulsed laser modification process, and improves its efficiency in the subsequent thinning process, thereby solving the problems of poor modification effect and poor modification controllability in the prior art. Summary of the invention

[0005] (I) Purpose of the invention

[0006] In view of the deficiencies in the prior art, an object of the present invention is to provide a method for improving the efficiency of semiconductor wafer thinning by coordinated regulation of temperature atmosphere, thereby achieving high-quality and efficient processing of laser modification and thinning processes.

[0007] (II) Technical solution

[0008] The present invention is achieved through the following technical solutions.

[0009] (1) cleaning the surface of the semiconductor wafer obtained by multi-wire cutting or laser stripping with anhydrous ethanol and drying it for later use;

[0010] (2) placing the cleaned and dried wafer in a low-temperature generator in the sample chamber, and sealing the low-temperature generator after setting the temperature;

[0011] (3) Turn on the flow regulating device to control the oxygen concentration inside the low-temperature generating device to be stable to a certain set value;

[0012] (4) Turn on the femtosecond laser, set the laser parameters, and start surface modification of the semiconductor wafer.

[0013] (5) During the laser modification process, the oxygen concentration value inside the low-temperature generator is monitored in real time by an oxygen concentration monitor, and the oxygen concentration is always maintained at an initial set value by a controller;

[0014] (6) The modified semiconductor wafer is ground and thinned by a thinning machine to obtain a final finished product sample.

[0015] Furthermore, the size of the semiconductor wafer in step (1) is two inches, four inches or six inches;

[0016] Furthermore, in step (2), the temperature of the low temperature generating device is set to -50°C to -100°C;

[0017] Furthermore, the oxygen concentration setting value in step (3) is 40% to 100%;

[0018] Furthermore, the laser parameters in step (4) include laser pulse width, laser wavelength, laser power, pulse frequency, scanning speed, scanning spacing, and number of scans, and their values ​​are set to 50fs-10ns, 1026nm, 6W-10W, 100KHz-1MHz, 10mm / s-50mm / s, 10-30μm, and 3-5 times, respectively.

[0019] (III) Beneficial effects

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

[0021] (1) The oxygen concentration regulating device proposed in the present invention can maintain the oxygen concentration of the system at a constant value, ensure the uniformity of the laser modified product, and utilize subsequent thinning and removal by adjusting the composition of the modified product.

[0022] (2) The low-temperature assisted laser modification method proposed in the present invention can effectively reduce the thermal effect generated by the laser during the processing, thereby reducing the damage of the laser to the sub-surface and improving the quality of the subsequent thinning and CMP processes.

[0023] (3) The laser-modified coupled atmosphere / low-temperature control method proposed in the present invention can significantly improve the subsequent thinning efficiency while optimizing the wafer quality. 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 This is a scanning electron microscope image of the cross section of the wafer obtained in Example 1.

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

[0027] Figure 4 The EDS atomic percentage data of the modified surface obtained in Example 1 and the EDS atomic percentage data of the laser-modified surface under air conditions. DETAILED DESCRIPTION

[0028] 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.

[0029] Embodiment 1:

[0030] (1) The six-inch silicon carbide wafer obtained by multi-wire cutting or laser stripping is surface cleaned with anhydrous ethanol and then dried for later use.

[0031] (2) The cleaned and dried wafer is placed in a low-temperature generator in the sample chamber, the temperature is set to -60°C, and then the low-temperature generator is sealed.

[0032] (3) Turn on the flow regulating device to control the oxygen concentration inside the low-temperature generating device to be stable at 100%.

[0033] (4) Turn on the femtosecond laser, set the laser pulse width, laser wavelength, laser power, pulse frequency, scanning speed, scanning spacing, and scanning times to 230 fs, 1026 nm, 8 W, 100 kHz, 20 mm / s, 10 μm, and 3 times, respectively, and start surface modification of the silicon carbide wafer.

[0034] (5) During the laser modification process, the oxygen concentration value inside the low-temperature generator is monitored in real time by an oxygen concentration monitor, and the oxygen concentration is always maintained at an initial set value by a controller;

[0035] (6) The modified silicon carbide wafer is ground and thinned by a thinning machine to obtain the final finished product sample.

[0036] Test results: Figure 2 This is a scanning electron microscope image of the cross section of the wafer obtained in Example 1. From the image, it can be seen that the laser modified layer is evenly distributed and the sub-surface quality is good.

[0037] Figure 3 This is a comparison chart of the hardness surface of the modified wafer obtained in Example 1 and the original silicon carbide wafer. It can be found that the surface hardness of the silicon carbide modified by this method is reduced by 23.645 GPa compared with the surface hardness of the original silicon carbide, indicating that this method can greatly improve the subsequent thinning efficiency of silicon carbide.

[0038] Figure 4 The EDS atomic percentage data of the modified surface obtained in Example 1 and the EDS atomic percentage data of the laser modified surface under air conditions are shown in Table 1. It can be found that under high oxygen concentration modification conditions, the surface composition does not contain C element, the composition is more uniform, and is only silicon oxide.

[0039] 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 method for improving semiconductor wafer thinning efficiency by coordinated temperature and atmosphere control, characterized in that The steps include: (1) cleaning the surface of the semiconductor wafer obtained by multi-wire cutting or laser stripping with anhydrous ethanol and drying it for later use; (2) placing the cleaned and dried wafer in a low-temperature generator in the sample chamber, and sealing the low-temperature generator after setting the temperature; (3) Turn on the flow regulating device to control the oxygen concentration inside the low-temperature generating device to be stable to a certain set value; (4) turning on the femtosecond laser, setting laser parameters, and starting surface modification of the semiconductor wafer; (5) During the laser modification process, the oxygen concentration value inside the low-temperature generator is monitored in real time by an oxygen concentration monitor, and the oxygen concentration is always maintained at an initial set value by a controller; (6) The modified semiconductor wafer is ground and thinned by a thinning machine to obtain the final finished product sample.

2. The method for improving semiconductor wafer thinning efficiency by coordinated temperature and atmosphere control according to claim 1, characterized in that: The size of the semiconductor wafer in step (1) is two inches, four inches or six inches.

3. The method for improving semiconductor wafer thinning efficiency by coordinated temperature and atmosphere control according to claim 1, characterized in that: In the step (2), the temperature of the low temperature generating device is set to -50°C to -100°C.

4. The method for improving semiconductor wafer thinning efficiency by coordinated temperature and atmosphere control according to claim 1, characterized in that: The oxygen concentration setting value in step (3) is 40% to 100%.

5. The method for improving semiconductor wafer thinning efficiency by coordinated temperature and atmosphere control according to claim 1, characterized in that: The laser parameters in step (4) include laser pulse width, laser wavelength, laser power, pulse frequency, scanning speed, scanning spacing, and scanning times, and their values ​​are set to 50fs-10ns, 1026nm, 6W-10W, 100KHz-1 MHz, 10mm / s-50mm / s, 10-30μm, and 3-5 times, respectively.

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