Surface treatment process before gettering of silicon wafer
By using SC cleaning solution, megasic wave cleaning and potassium hydroxide corrosion treatment in the surface treatment process of silicon wafers before absorbing miscibility, the problem of difficult to remove impurities in the surface damage layer of silicon wafers in the prior art has been solved, and the silicon wafers have been significantly improved Cleanliness and battery performance.
Patent Information
- Application Number
- CN202411385048.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-30
- Publication Date
- 2025-01-07
AI Technical Summary
The prior art is difficult to effectively remove impurities in the damaged layer on the surface of the silicon wafer, affecting the subsequent miscible absorption effect and battery performance.
The surface treatment process of silicon wafer miscible presorption is adopted, including soaking in SC cleaning solution to remove organic matter, megasic wave cleaning, plasma cleaning and potassium hydroxide corrosion treatment, combined with nitrogen purge, to remove impurities from the surface and damaged layer.
It significantly improves the cleanliness of the silicon wafer, reduces the surface roughness and particle count, and improves the conversion efficiency of the battery.
Smart Images
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Abstract
Description
Technical Field
[0001] The present application relates to the field of semiconductor manufacturing technology, and in particular to a surface treatment process before silicon wafer gettering. Background Art
[0002] In the semiconductor manufacturing process, the cleanliness of the silicon wafer surface directly affects the performance and yield of the device; silicon wafer gettering refers to the process of removing impurities, defects or contaminants from the surface or near the surface of the silicon wafer during the semiconductor manufacturing process. The goal of impurity gettering technology is to improve the cleanliness of silicon wafers and ensure that subsequent processes such as deposition, lithography, etching, etc. can proceed smoothly, thereby improving the quality and output of finished products; the industrialization of silicon wafer gettering mainly adopts chain gettering, which is an important way to getter impurities in batteries at present because of its short process time, rapid temperature control, and rapid cooling.
[0003] In order to improve the cleanliness of silicon wafers after impurity gettering, the prior art generally washes away impurities on the surface of the silicon wafer. However, the processing technology in the prior art can only remove silicon powder, oil stains, etc. on the surface of the silicon wafer, but fails to better remove impurities in the damaged layer, which is not conducive to subsequent impurity gettering. Summary of the invention
[0004] In order to solve the above technical problems, the present application provides a silicon wafer surface treatment process before doping.
[0005] The surface treatment process before silicon wafer gettering includes the following steps:
[0006] Step 1: Soak the silicon wafer in SC cleaning solution to remove organic matter, then rinse it with deionized water;
[0007] Step 2: Place the silicon wafer in a megasonic cleaning tank, use a megasonic cleaning device to clean the silicon wafer in deionized water, and then rinse it with deionized water after taking it out;
[0008] Step 4: Immerse the silicon wafer in potassium hydroxide etching solution;
[0009] Step 5: Use a nitrogen purge device to dry the silicon wafer.
[0010] As a further technical solution of the present invention, between step 2 and step 4, it also includes:
[0011] Step 3: Place the silicon wafer in a plasma cleaning device for treatment, and rinse it with deionized water after taking it out.
[0012] As a further technical solution of the present invention, in step 1, the SC cleaning solution includes ammonium hydroxide, hydrogen peroxide and deionized water, and the mass ratio of ammonium hydroxide, hydrogen peroxide and deionized water in the SC cleaning solution is 1:1:5.
[0013] As a further technical solution of the present invention, in step 1, the immersion time of the silicon wafer is 5-10 minutes, and the immersion temperature is 70-80°C.
[0014] As a further technical solution of the present invention, in step 2, the frequency of the megasonic cleaning equipment is 1-2 MHz, and the cleaning time of the silicon wafer is 3-5 minutes.
[0015] As a further technical solution of the present invention, in step three, the plasma source is oxygen or argon.
[0016] As a further technical solution of the present invention, in step three, the power of the plasma cleaning equipment is 200-300W, and the processing time is 2-3min.
[0017] As a further technical solution of the present invention, in step 4, the concentration of the potassium hydroxide etching solution is 1%-2%.
[0018] As a further technical solution of the present invention, in step 4, the processing temperature of the silicon wafer is 60° C.-80° C., and the processing time is 2-5 minutes.
[0019] As a further technical solution of the present invention, in step 4, the etching depth of the silicon wafer is 1-2 μm.
[0020] In summary, the present invention includes at least one of the following beneficial technical effects:
[0021] The present application adds potassium hydroxide corrosion treatment to the pre-treatment of silicon wafers for doping removal, and uses potassium hydroxide corrosion liquid to corrode the silicon wafers after the organic matter is removed, so as to remove the damaged layer in the silicon wafer, which is more conducive to doping removal and can improve the conversion efficiency of the manufactured battery performance. DETAILED DESCRIPTION
[0022] The following examples further illustrate the present application in detail.
[0023] This application provides a silicon wafer surface treatment process before gettering, and the specific steps are as follows:
[0024] Step 1: Soak the silicon wafer in SC cleaning solution to remove organic matter, the soaking time is 5-10 minutes, the soaking temperature is 70-80°C, and then rinse it with deionized water; the SC cleaning solution includes ammonium hydroxide, hydrogen peroxide and deionized water, and the mass ratio of ammonium hydroxide, hydrogen peroxide and deionized water in the SC cleaning solution is 1:1:5;
[0025] Ammonium hydroxide is used to provide an alkaline environment. Hydrogen peroxide has an oxidizing effect and can decompose organic matter on the surface of the silicon wafer.
[0026] Step 2: Place the silicon wafer in a megasonic cleaning tank and use a megasonic cleaning device to clean the silicon wafer in deionized water. The cleaning time is 3-5 minutes and the frequency is 1-2MHz. After taking it out, rinse it with deionized water.
[0027] Megasonic cleaning uses the shock waves of tiny bubbles generated by high-frequency sound waves when they burst to remove particles from the surface of silicon wafers;
[0028] Step 3: Place the silicon wafer in a plasma cleaning device for treatment. The plasma source is oxygen or argon, the power is 200-300W, and the treatment time is 2-3min. After taking it out, rinse it with deionized water;
[0029] Plasma cleaning uses active particles in the plasma to react with organic matter on the surface of the silicon wafer, decomposing it into volatile small molecules, thereby further removing the organic matter.
[0030] Step 4: Immerse the silicon wafer in a 1%-2% potassium hydroxide etching solution and perform etching treatment at 60°C-80°C for 2-5 minutes; the etching depth is 1-2 μm;
[0031] Potassium hydroxide, as a strong base, can react chemically with silicon to remove the damaged layer on the surface of the silicon wafer;
[0032] Step 5: Use a nitrogen purge device to dry the silicon wafer.
[0033] Example 1
[0034] This embodiment provides a surface treatment process for silicon wafers before gettering, and the specific steps are as follows:
[0035] Step 1: Soak the silicon wafer in SC cleaning solution to remove organic matter. The soaking time is 5 minutes and the soaking temperature is 80°C. After taking it out, rinse it with deionized water.
[0036] Step 2: Place the silicon wafer in a megasonic cleaning tank and use a megasonic cleaning device to clean the silicon wafer in deionized water. The cleaning time is 5 minutes and the frequency is 1 MHz. After taking it out, rinse it with deionized water.
[0037] Step 3: Immerse the silicon wafer in a 1% potassium hydroxide etching solution and perform etching treatment at 60°C for 5 minutes; the etching depth is 1 μm;
[0038] Step 4: Use a nitrogen purge device to dry the silicon wafer.
[0039] Example 2
[0040] This embodiment provides a surface treatment process for silicon wafers before gettering, and the specific steps are as follows:
[0041] Step 1: Soak the silicon wafer in SC cleaning solution to remove organic matter. The soaking time is 10 minutes and the soaking temperature is 70°C. After taking it out, rinse it with deionized water.
[0042] Step 2: Place the silicon wafer in a megasonic cleaning tank and use a megasonic cleaning device to clean the silicon wafer in deionized water. The cleaning time is 3 minutes and the frequency is 2 MHz. After taking it out, rinse it with deionized water.
[0043] Step 3: Immerse the silicon wafer in a 1.5% potassium hydroxide etching solution and perform etching treatment at 80°C for 2 minutes; the etching depth is 1.5 μm;
[0044] Step 4: Use a nitrogen purge device to dry the silicon wafer.
[0045] Example 3
[0046] This embodiment provides a surface treatment process for silicon wafers before gettering, and the specific steps are as follows:
[0047] Step 1: Soak the silicon wafer in SC cleaning solution to remove organic matter. The soaking time is 8 minutes and the soaking temperature is 75°C. After taking it out, rinse it with deionized water.
[0048] Step 2: Place the silicon wafer in a megasonic cleaning tank and use a megasonic cleaning device to clean the silicon wafer in deionized water. The cleaning time is 4 minutes and the frequency is 1.5 MHz. After taking it out, rinse it with deionized water.
[0049] Step 3: Immerse the silicon wafer in a 2% potassium hydroxide etching solution and perform etching treatment at 70° C. for 4 minutes; the etching depth is 2 μm;
[0050] Step 4: Use a nitrogen purge device to dry the silicon wafer.
[0051] Example 4
[0052] This embodiment provides a surface treatment process for silicon wafers before gettering, and the specific steps are as follows:
[0053] Step 1: Soak the silicon wafer in SC cleaning solution to remove organic matter. The soaking time is 5-10 minutes and the soaking temperature is 75°C. After taking it out, rinse it with deionized water;
[0054] Step 2: Place the silicon wafer in a megasonic cleaning tank and use a megasonic cleaning device to clean the silicon wafer in deionized water. The cleaning time is 3 minutes and the frequency is 2 MHz. After taking it out, rinse it with deionized water.
[0055] Step 3: Immerse the silicon wafer in a 1.5% potassium hydroxide etching solution and perform etching treatment at 75°C for 3 minutes; the etching depth is 1.3 μm;
[0056] Step 4: Use a nitrogen purge device to dry the silicon wafer.
[0057] Comparative Example 1
[0058] The specific steps of silicon wafer surface treatment process before gettering are as follows:
[0059] Step 1: Soak the silicon wafer in SC cleaning solution to remove organic matter. The soaking time is 5 minutes and the soaking temperature is 80°C. After taking it out, rinse it with deionized water.
[0060] Step 2: Place the silicon wafer in a megasonic cleaning tank and use a megasonic cleaning device to clean the silicon wafer in deionized water. The cleaning time is 5 minutes and the frequency is 1 MHz. After taking it out, rinse it with deionized water.
[0061] Step 3: Use a nitrogen purge device to dry the silicon wafer.
[0062] Performance testing: The silicon wafers cleaned in the above-mentioned Examples 1-4 and Comparative Examples 1-4 were tested, and the testing method was as follows.
[0063] Surface roughness testing: Use atomic force microscopy to evaluate the flatness of the silicon wafer surface;
[0064] Particle size detection: Use a scanning electron microscope to detect the particle size on the surface of the silicon wafer;
[0065] Conversion efficiency test: getter the silicon wafer and make it into a battery, and then get the conversion efficiency of the battery;
[0066] The above-mentioned detection method was used to perform performance detection on the cleaned silicon wafers in the above-mentioned Examples 1-4 and Comparative Examples 1-4. The detection results are shown in Table 1.
[0067] Table 1
[0068]
[0069]
[0070] As can be seen from Table 1, the arithmetic average roughness of the silicon wafers after etching with potassium hydroxide in Examples 1-4 is reduced from 0.41nm to below 0.34nm compared to the silicon wafer without removing the damaged layer in Comparative Example 1, and reaches the lowest point of 0.31nm in Example 2; at the same time, the number of particles with a size of >0.1μm on the surface of the silicon wafer is reduced from 65 / cm 2 Reduced to 46 / cm 2Below, and in Example 2, the minimum value of 41 / cm 2 ; And the conversion efficiency of the battery performance produced by Examples 1-4 is improved by 0.1%-0.18% compared with Comparative Example 1, indicating that the silicon wafer after the cleaning treatment of the present application has a better impurity absorption effect, and the conversion efficiency of the battery performance produced is significantly improved.
[0071] The applicant discovered that the removal of organic matter on the surface of the silicon wafer before etching will affect the subsequent etching effect. On this basis, the applicant designed Examples 5 to 7 based on Example 2, in which the applicant added an organic matter treatment step between the original step 2 and the original step 3 as a new step 3, and the original step 3 became step 4. Other than that, everything else remained unchanged, as follows;
[0072] Example 5
[0073] This embodiment provides a surface treatment process for silicon wafers before gettering, and the specific steps are as follows:
[0074] Step 1: Soak the silicon wafer in SC cleaning solution to remove organic matter. The soaking time is 10 minutes and the soaking temperature is 70°C. After taking it out, rinse it with deionized water.
[0075] Step 2: Place the silicon wafer in a megasonic cleaning tank and use a megasonic cleaning device to clean the silicon wafer in deionized water. The cleaning time is 3 minutes and the frequency is 2 MHz. After taking it out, rinse it with deionized water.
[0076] Step 3: Place the silicon wafer in a plasma cleaning device for treatment. The plasma source is oxygen, the power is 200W, and the treatment time is 2min. After taking it out, rinse it with deionized water;
[0077] Step 4: Immerse the silicon wafer in a 1% potassium hydroxide etching solution and perform etching treatment at 60°C for 5 minutes; the etching depth is 1 μm;
[0078] Step 5: Use a nitrogen purge device to dry the silicon wafer.
[0079] Example 6
[0080] This embodiment provides a surface treatment process for silicon wafers before gettering, and the specific steps are as follows:
[0081] Step 1: Soak the silicon wafer in SC cleaning solution to remove organic matter. The soaking time is 10 minutes and the soaking temperature is 70°C. After taking it out, rinse it with deionized water.
[0082] Step 2: Place the silicon wafer in a megasonic cleaning tank and use a megasonic cleaning device to clean the silicon wafer in deionized water. The cleaning time is 3 minutes and the frequency is 2 MHz. After taking it out, rinse it with deionized water.
[0083] Step 3: Place the silicon wafer in a plasma cleaning device for treatment. The plasma source is oxygen, the power is 250W, and the treatment time is 3 minutes. After taking it out, rinse it with deionized water;
[0084] Step 4: Immerse the silicon wafer in a 1% potassium hydroxide etching solution and perform etching treatment at 60°C for 5 minutes; the etching depth is 1 μm;
[0085] Step 5: Use a nitrogen purge device to dry the silicon wafer.
[0086] Example 7
[0087] This embodiment provides a surface treatment process for silicon wafers before gettering, and the specific steps are as follows:
[0088] Step 1: Soak the silicon wafer in SC cleaning solution to remove organic matter. The soaking time is 10 minutes and the soaking temperature is 70°C. After taking it out, rinse it with deionized water.
[0089] Step 2: Place the silicon wafer in a megasonic cleaning tank and use a megasonic cleaning device to clean the silicon wafer in deionized water. The cleaning time is 3 minutes and the frequency is 2 MHz. After taking it out, rinse it with deionized water.
[0090] Step 3: Place the silicon wafer in a plasma cleaning device for treatment. The plasma source is oxygen, the power is 300W, and the treatment time is 2.5min. After taking it out, rinse it with deionized water;
[0091] Step 4: Immerse the silicon wafer in a 1% potassium hydroxide etching solution and perform etching treatment at 60°C for 5 minutes; the etching depth is 1 μm;
[0092] Step 5: Use a nitrogen purge device to dry the silicon wafer.
[0093] The performance of the silicon wafers cleaned in the above-mentioned Examples 5-7 was tested by the above-mentioned testing method. The test results are shown in Table 2.
[0094] Table 2
[0095]
[0096] As can be seen from Table 2, compared with the silicon wafer in Example 2, the arithmetic mean roughness of the silicon wafers in Examples 5-7 is reduced from 0.31nm to below 0.3nm, and reaches the lowest point of 0.27nm in Example 7; at the same time, the number of particles with a size of >0.1μm on the surface of the silicon wafer is reduced from 41 / cm 2 Reduced to 39 / cm 2 Below, and in Example 7, the minimum value of 36 / cm 2 ; And the conversion efficiency of the battery performance produced by Examples 5-7 is improved by 0.01%-0.02% compared with Example 2, indicating that before the silicon wafer corrosion treatment, effective organic treatment can further enhance the corrosion effect, thereby making the subsequent impurity absorption effect better, and the conversion efficiency of the battery performance produced is further improved.
[0097] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.
Claims
1. A silicon wafer surface treatment process before gettering, characterized in that: The steps include: Step 1: Soak the silicon wafer in SC cleaning solution to remove organic matter, then rinse it with deionized water; Step 2: Place the silicon wafer in a megasonic cleaning tank, use a megasonic cleaning device to clean the silicon wafer in deionized water, and then rinse it with deionized water after taking it out; Step 4: Immerse the silicon wafer in potassium hydroxide etching solution; Step 5: Use a nitrogen purge device to dry the silicon wafer.
2. The silicon wafer surface treatment process before gettering according to claim 1, characterized in that: Between step 2 and step 4, it also includes: Step 3: Place the silicon wafer in a plasma cleaning device for treatment, and rinse it with deionized water after taking it out.
3. The process for surface treatment of silicon wafer before gettering according to claim 2, characterized in that: In step 1, the SC cleaning solution includes ammonium hydroxide, hydrogen peroxide and deionized water, and the mass ratio of ammonium hydroxide, hydrogen peroxide and deionized water in the SC cleaning solution is 1:1:
5.
4. The process for surface treatment of silicon wafer before gettering according to claim 2, characterized in that: In step 1, the immersion time of the silicon wafer is 5-10 minutes, and the immersion temperature is 70-80°C.
5. The process for surface treatment of silicon wafer before gettering according to claim 2, characterized in that: In step 2, the frequency of the megasonic cleaning equipment is 1-2 MHz, and the cleaning time of the silicon wafer is 3-5 minutes.
6. The process for surface treatment of silicon wafer before gettering according to claim 2, characterized in that: In step three, the plasma source is oxygen or argon.
7. The process for surface treatment of silicon wafer before gettering according to claim 2, characterized in that: In step three, the power of the plasma cleaning equipment is 200-300W, and the processing time is 2-3min.
8. The process for surface treatment of silicon wafer before gettering according to claim 2, characterized in that: In step 4, the concentration of the potassium hydroxide corrosive solution is 1%-2%.
9. The process for surface treatment of silicon wafer before gettering according to claim 2, characterized in that: In step 4, the processing temperature of the silicon wafer is 60° C.-80° C., and the processing time is 2-5 minutes.
10. The process for surface treatment of silicon wafer before gettering according to claim 2, characterized in that: In step 4, the etching depth of the silicon wafer is 1-2 μm.