Method for improving semiconductor wafer thinning efficiency through photochemistry assistance

Abstract

The invention discloses a method for improving semiconductor wafer thinning efficiency through photochemistry assistance. The method comprises the following steps: performing ion implantation on the surface of a wafer; then laser modification treatment is further carried out on the softened ion implantation modified surface, so that a low-hardness modified layer is efficiently obtained; then element deposition and annealing treatment are conducted on the laser modified surface through a magnetron sputtering device, and the hardness of the laser modified surface is further improved through a chemical metallurgical reaction; and finally, the modified wafer is thinned and polished through a wafer thinning machine or chemical mechanical polishing treatment, so that a final finished sample wafer is obtained. The method has the advantages of being efficient, high in repeatability and the like, the advantages of several kinds of photochemical modification methods are combined, and the follow-up thinning efficiency and quality of the wafer can be effectively improved.

Description

Technical Field

[0001] The invention belongs to the technical field of laser-assisted processing, and in particular relates to a method for improving semiconductor wafer thinning efficiency with photochemical assistance. Background Art

[0002] Semiconductor materials such as silicon carbide (SiC) are third-generation wide-bandgap semiconductor materials with excellent physical and chemical properties. Due to their high hardness, high temperature resistance, and corrosion resistance, they are currently widely used in high-power and high-frequency devices, especially in new energy, aerospace, and high-temperature power electronic devices. However, the processing of such wafers is extremely difficult, especially in the wafer thinning stage. Traditional mechanical grinding and chemical mechanical polishing processes are inefficient and easily cause surface and subsurface damage to the wafer, including cracks, defects, and particle contamination. These defects will seriously affect the yield and device performance in subsequent device manufacturing.

[0003] In order to solve the above problems, researchers have tried to combine chemical etching, laser-assisted and other technical means to improve the surface modification effect of hard and brittle semiconductor wafers, but the comprehensive modification efficiency and quality still cannot meet the actual needs. Therefore, an efficient method is urgently needed to optimize the thinning process of silicon carbide wafers, reduce processing damage and improve processing efficiency.

[0004] The present invention combines the advantages of multiple types of modification processes and can effectively regulate the hardness, composition and structure of the semiconductor wafer surface, thereby improving the quality and efficiency of the semiconductor wafer thinning process. Summary of the invention

[0005] (I) Purpose of the invention

[0006] In view of the deficiencies in the prior art, the object of the present invention is to provide a method for photochemically assisted improvement of semiconductor wafer thinning efficiency, aiming to improve the efficiency and quality of the wafer thinning process.

[0007] (II) Technical solution

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

[0009] (1) Pre-treating the surface of the semiconductor wafer after cutting or mechanical polishing to remove impurities, particles and contaminants on the surface to ensure the cleanliness of the wafer surface;

[0010] (2) setting ion implantation parameters and implanting ions into the pretreated wafer using an ion implantation device;

[0011] (3) turning on the laser, setting laser parameters, and performing femtosecond laser modification treatment on the surface of the semiconductor wafer after ion implantation;

[0012] (4) Setting magnetron sputtering parameters, using a magnetron sputtering coating machine to deposit chemical elements on the surface of the semiconductor wafer modified by the femtosecond laser, and performing annealing after the deposition.

[0013] (5) The annealed semiconductor wafer is subjected to grinding and thinning or chemical mechanical polishing by a thinning machine to obtain a final finished product sample;

[0014] Furthermore, the type of ions implanted in step (2) is one of hydrogen ions, helium ions, silicon ions, copper ions, gallium ions or argon ions;

[0015] Furthermore, the parameters of ion implantation in step (2) include implantation energy, implantation dose, and implantation temperature, and their values ​​are set to 20keV-500keV, 1×10 15 cm -2 -1×10 17 cm -2 , 25-500℃;

[0016] Furthermore, the 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 30fs-500fs, 343nm, 4W-12W, 100KHz-1MHz, 5mm / s-100mm / s, 10-50μm, and 2-10 times, respectively;

[0017] Furthermore, the magnetron sputtering element in step (4) is one of nickel and aluminum;

[0018] Furthermore, the magnetron sputtering parameters in step (4) include sputtering power, sputtering pressure, film thickness range, and sputtering temperature, and their values ​​are 50W-500W, 1Pa-10Pa, 10nm-1μm, and 25-400°C, respectively.

[0019] (III) Beneficial effects

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

[0021] (1) The ion implantation method proposed in the present invention can form microstructural defects on the surface of semiconductor wafers, significantly reducing the hardness of the material.

[0022] (2) The femtosecond laser modification strategy proposed in the present invention can further improve the modification efficiency based on ion implantation to soften the surface.

[0023] (3) The magnetron sputtering method proposed in the present invention can effectively produce a chemical metallurgical reaction with the laser-modified product / substrate structure to form a modified substance that is easier to remove, thereby improving the subsequent thinning efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic flow chart of the method for photochemical treatment of semiconductor wafers in the present invention.

[0025] Figure 2 This is a comparison chart of the hardness of the modified wafer surface obtained in Example 1 and the original silicon carbide wafer surface.

[0026] Figure 3 This is a comparison chart of the average material removal rate (MRR) of the CMP chemical mechanical polishing technology obtained in Example 1 and the CMP after being processed by the solution of the present invention within a polishing time of 40 minutes. 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) Pre-treat the surface of the silicon carbide wafer after cutting or mechanical polishing to remove impurities, particles and contaminants on the surface to ensure the cleanliness of the wafer surface.

[0030] (2) Set the ion implantation parameters, including implantation energy, implantation dose, and implantation temperature, and set their values ​​to 200 keV, 1×10 15 cm -2 , 300°C, the implanted ion type is gallium ion, and the pre-treated wafer is implanted with an ion implantation device.

[0031] (3) Turn on the laser and set the laser parameters, including laser pulse width, laser wavelength, laser power, pulse frequency, scanning speed, scanning spacing, and scanning times, with the values ​​being set to 230 fs, 343 nm, 8 W, 100 kHz, 10 mm / s, 10 μm, and 2 times, respectively, and perform femtosecond laser modification on the surface of the silicon carbide wafer after ion implantation.

[0032] (4) setting magnetron sputtering parameters, including sputtering power, sputtering pressure, film thickness, and sputtering temperature, whose values ​​are 100 W, 5 Pa, 1 μm, and 300 ° C, respectively; the magnetron sputtering element is nickel; and a magnetron sputtering coating machine is used to deposit chemical elements on the surface of the silicon carbide wafer modified by the femtosecond laser, and annealing is performed after the deposition is completed;

[0033] (5) The annealed silicon carbide wafer is subjected to chemical mechanical polishing to obtain the final finished product sample.

[0034] Test results: Figure 2This is a comparison chart of the surface hardness of the modified wafer obtained in Example 1 and the original silicon carbide wafer. It can be found that the surface hardness of the material is significantly reduced after modification by this method.

[0035] Figure 3 This is a comparison chart of the average material removal rate (MRR) of the CMP chemical mechanical polishing technology obtained in Example 1 and the CMP after processing by the solution of the present invention within a polishing time of 40 minutes. It can be found that the material removal efficiency of the wafer modified by this method during the CMP process is improved by about eight times compared with the original CMP method.

[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 method for photochemically assisted improvement of semiconductor wafer thinning efficiency, characterized in that The steps include: (1) Pre-treating the surface of the semiconductor wafer after cutting or mechanical polishing to remove impurities, particles and contaminants on the surface to ensure the cleanliness of the wafer surface; (2) setting ion implantation parameters and implanting ions into the pretreated wafer using an ion implantation device; (3) turning on the laser, setting laser parameters, and performing femtosecond laser modification treatment on the surface of the semiconductor wafer after ion implantation; (4) setting magnetron sputtering parameters, using a magnetron sputtering coating machine to deposit chemical elements on the surface of the semiconductor wafer modified by the femtosecond laser, and performing annealing after the deposition; (5) The annealed semiconductor wafer is subjected to grinding and thinning or chemical mechanical polishing by a thinning machine to obtain the final finished product sample.

2. The method of photochemically assisted semiconductor wafer thinning efficiency according to claim 1, characterized in that: The type of ions implanted in step (2) is one of hydrogen ions, helium ions, silicon ions, copper ions, gallium ions or argon ions.

3. The method of photochemically assisted semiconductor wafer thinning efficiency according to claim 1, characterized in that: The parameters of ion implantation in step (2) include implantation energy, implantation dose, and implantation temperature, and the values ​​thereof are set to 20keV-500keV, 1×10 15 cm- 2 -1×10 17 cm- 2 , 25-500℃.

4. The method of photochemically assisted semiconductor wafer thinning efficiency according to claim 1, characterized in that: The 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 30fs-500fs, 343nm, 4W-12W, 100KHz-1MHz, 5mm / s-100mm / s, 10-50μm, and 2-10 times, respectively.

5. The method of photochemically assisted semiconductor wafer thinning efficiency improvement according to claim 1, characterized in that: The magnetron sputtering element in step (4) is one of nickel and aluminum.

6. The method of photochemically assisted semiconductor wafer thinning efficiency according to claim 1, characterized in that: The magnetron sputtering parameters in step (4) include sputtering power, sputtering pressure, film thickness range, and sputtering temperature, and their values ​​are 50W-500W, 1Pa-10Pa, 10nm-1μm, and 25-400°C, respectively.

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