A novel method for electrophoretic pretreatment of silicon wafer

Abstract

The present application relates to a new type of silicon wafer electrophoresis pretreatment method, which adds weak acid treatment before and after the treatment step in sulfuric acid and hydrogen peroxide solution. The method is simple, can reduce the breakage rate of products, improve the strength of silicon wafers, ensure the safety of operation, and can also clean the grooves of silicon wafers, so that the quality and reliability of products are improved.

Description

A novel pretreatment method for silicon wafer electrophoresis Technical Field

[0001] This invention relates to the field of silicon wafer cleaning technology, and pertains to a novel method for pretreatment of silicon wafers before electrophoresis. Background Technology

[0002] The cleaning process of silicon wafers before electrophoresis is crucial to their electrical properties. Traditional processes use solutions 1 and 2 for cleaning, both of which require heating (typically 100-130°C) and involve large quantities of acid. This high acid usage necessitates careful acid handling. Solutions 1 and 2 only clean the surface of the wafers, while sulfuric acid cleans the grooves after the adhesive has been burned off. However, directly immersing the wafers in 100-130°C sulfuric acid and hydrogen peroxide causes a sudden heating, resulting in cracking sounds and wafer breakage. When the wafers are rinsed in running water after sulfuric acid and hydrogen peroxide cleaning, the sulfuric acid reacts with the water, generating significant heat and splashing, causing the cracking sounds again and ultimately leading to wafer breakage. Approximately 2 out of 150 wafers break, a breakage rate of 1.3%. This sudden heating and cooling process negatively impacts the strength of the silicon wafers. Summary of the Invention

[0003] To address the problems in the background technology, this invention provides a novel pretreatment method for silicon wafer electrophoresis. By adding glacial acetic acid treatment before and after the treatment steps in sulfuric acid and hydrogen peroxide solution, this invention not only cleans the grooves of the silicon wafer and reduces the leakage current value of the product, but also ensures the strength of the silicon wafer, thereby improving the quality and reliability of the product.

[0004] The technical solution adopted by this invention to solve its technical problem is: a novel silicon wafer electrophoresis pretreatment method, comprising the following steps:

[0005] (1) Take the silicon wafer after the glue has been burned and treat it in a weak acid for 15-45 seconds;

[0006] (2) Treat in sulfuric acid and hydrogen peroxide solution for 6-10 min;

[0007] (3) Treat in a weak acid for 15–45 seconds;

[0008] (4) Rinse with running pure water for 5-10 minutes;

[0009] (5) Perform ultrasonic cleaning in still pure water for 15-20 minutes;

[0010] (6) Perform the final rinse in the water tank and observe the cleanliness of the material. The water resistance of the final rinse is ≥10MΩcm.

[0011] Preferably, the weak acid is glacial acetic acid, which is of electronic grade and is consumed at a temperature of 20–30°C.

[0012] Preferably, the sulfuric acid and hydrogen peroxide solution is at a temperature of 110–130°C, the ratio of sulfuric acid to hydrogen peroxide is 10:1, the sulfuric acid is of electronic grade and the concentration is ≥98%, and the hydrogen peroxide is of electronic grade.

[0013] Preferably, the ultrasonic amplitude in step (5) is 15-25 mV.

[0014] Preferably, the purity of the pure water in steps (4) and (5) is ≥99.99%.

[0015] Preferably, the step (1) of treating in a weak acid is to first treat in carbonic acid for 15-30 seconds, and then treat in glacial acetic acid for 15-30 seconds.

[0016] Preferably, the step (3) of treating in a weak acid is to first treat in glacial acetic acid for 15-30 seconds, and then treat in carbonic acid for 15-30 seconds.

[0017] Preferably, the carbonic acid is of electronic grade and the temperature is 20-30°C.

[0018] The water resistance value of the last stage of rinsing refers to the resistance value of the pure water at the inlet of the water tank, which is required to be ≥10 MΩcm. The last stage of rinsing is a way to observe the cleanliness of the materials.

[0019] An additional treatment with glacial acetic acid is added before and after the sulfuric acid and hydrogen peroxide solution steps. Glacial acetic acid primarily serves a passivation function, acting as a buffer. After the silicon wafers are treated with glacial acetic acid, they are then immersed in the sulfuric acid and hydrogen peroxide solution. Here, the glacial acetic acid acts as a buffer, preventing the wafers from cracking or breaking. When the silicon wafers are removed from the sulfuric acid and hydrogen peroxide solution, they are then immersed in glacial acetic acid. Again, the glacial acetic acid acts as a buffer, preventing excessive heat release and wafer breakage before the final immersion in water. This ensures both thorough cleaning and maintains the strength of the silicon wafers, ultimately improving and stabilizing product quality.

[0020] Experiments show that adding carbonic acid treatment before glacial acetic acid treatment in step (1) results in better passivation of silicon wafers, and adding carbonic acid treatment after glacial acetic acid treatment in step (3) results in weaker heat release from the silicon wafers in water, and more stable product quality after final treatment.

[0021] The beneficial effects of this invention are: the method of this invention is simple, it not only cleans the silicon wafer trenches and reduces the leakage current value of the product, but also ensures the strength of the silicon wafer, thereby improving the quality and reliability of the product. Detailed Implementation

[0022] The principles and features of the present invention are described below. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0023] Example 1

[0024] (1) Take the silicon wafer after the adhesive has been burned and treat it in glacial acetic acid for 20 seconds;

[0025] (2) Treat in a sulfuric acid and hydrogen peroxide solution with a sulfuric acid to hydrogen peroxide ratio of 10:1 and a temperature of 110 to 130°C for 7 min;

[0026] (3) Treat in glacial acetic acid for 20 seconds;

[0027] (4) Rinse with running pure water for 8 minutes;

[0028] (5) Perform ultrasonic cleaning in still pure water for 17 minutes with an amplitude of 15mV;

[0029] (6) Perform the final rinse in the water tank and observe the cleanliness of the material. The water resistance of the final rinse is 11 MΩcm.

[0030] The fragmentation rate was 0% after processing.

[0031] Example 2

[0032] (1) Take the silicon wafer after the glue has been burned off, treat it in carbonic acid for 20 seconds, and then treat it in glacial acetic acid for 20 seconds;

[0033] (2) Treat in a sulfuric acid and hydrogen peroxide solution with a sulfuric acid to hydrogen peroxide ratio of 10:1 and a temperature of 110 to 130°C for 9 min;

[0034] (3) First treat in glacial acetic acid for 20 seconds, then treat in carbonic acid for 20 seconds;

[0035] (4) Rinse with running pure water for 9 minutes;

[0036] (5) Perform ultrasonic cleaning in still pure water for 18 minutes with an amplitude of 25mV;

[0037] (6) Perform the final rinse in the water tank and observe the cleanliness of the material. The water resistance of the final rinse is 12 MΩcm.

[0038] The fragmentation rate was 0% after processing.

[0039] Comparative Example

[0040] (1) Take the silicon wafer after the glue has been burned and treat it in a sulfuric acid and hydrogen peroxide solution with a ratio of sulfuric acid to hydrogen peroxide of 10:1 and a temperature of 110-130℃ for 9 minutes.

[0041] (2) Rinse with running pure water for 10 minutes;

[0042] (3) Perform ultrasonic cleaning in still pure water for 20 minutes with an amplitude of 25mV;

[0043] (4) Perform the final rinse in the water tank and observe the cleanliness of the material. The water resistance of the final rinse is 12 MΩcm.

[0044] The fragmentation rate after processing was 1.33%.

[0045] Adding glacial acetic acid treatment before and after the sulfuric acid and hydrogen peroxide solution treatment steps reduces the silicon wafer breakage rate, increases the strength of the silicon wafer, ensures operational safety, and also cleans the silicon wafer trenches thoroughly, thereby improving product quality and reliability.

[0046] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A novel method for pretreatment of silicon wafers before electrophoresis, characterized in that, The process includes the following steps: (1) treating the silicon wafer after the adhesive has been burned in a weak acid for 15-45 seconds; (2) treating it in a sulfuric acid or hydrogen peroxide solution for 6-10 minutes; (3) treating it in a weak acid for 15-45 seconds; (4) rinsing it with running pure water for 5-10 minutes; (5) performing ultrasonic cleaning in still pure water for 15-20 minutes; (6) performing a final rinse in a water tank and observing the cleanliness of the material. The water resistance of the final rinse is ≥10 MΩcm. The weak acid is glacial acetic acid, which is of electronic grade and has a temperature of 20-30°C. The step of treating it in the weak acid in step (1) is to first treat it in carbonic acid for 15-30 seconds and then in glacial acetic acid for 15-30 seconds. The step of treating it in the weak acid in step (3) is to first treat it in glacial acetic acid for 15-30 seconds and then in carbonic acid for 15-30 seconds.

2. The novel silicon wafer electrophoresis pretreatment method according to claim 1, characterized in that, The sulfuric acid and hydrogen peroxide solution is at a temperature of 110–130°C, with a sulfuric acid to hydrogen peroxide ratio of 10:

1. The sulfuric acid is of electronic grade and has a concentration of ≥98%. The hydrogen peroxide is of electronic grade.

3. The novel silicon wafer electrophoresis pretreatment method according to claim 1, characterized in that, The ultrasonic amplitude in step (5) is 15-25 mV.

4. The novel silicon wafer electrophoresis pretreatment method according to claim 1, characterized in that, The purity of the pure water in steps (4) and (5) is ≥99.99%.

5. The novel silicon wafer electrophoresis pretreatment method according to claim 1, characterized in that, The carbonic acid is of electronic grade and is produced at a temperature of 20–30°C.