Cleaning method for improving 19nm particle level of 12-inch wafer

Abstract

The invention relates to the technical field of semiconductor materials, in particular to a cleaning method for improving the 19nm particle level of a 12-inch wafer, which comprises the following steps of: 1, putting the wafer into a pre-cleaning tank, and pre-cleaning by using an alkaline solution containing a surfactant; step 2, putting the pre-cleaned wafer into an SC1 cleaning tank, and cleaning with a mixed solution of ammonia water, hydrogen peroxide and deionized water; 3, putting the wafer cleaned by the SC1 into an SC2 cleaning tank, and cleaning by using a mixed solution of hydrochloric acid, hydrogen peroxide and deionized water; step 4, putting the wafer after SC2 cleaning into a DHF cleaning tank, and cleaning by using a diluted hydrofluoric acid solution; step 5, putting the wafer into a megasonic cleaning tank, and performing megasonic cleaning by using deionized water; and 6, rotary washing and drying: putting the wafer into a rotary washing and drying machine, carrying out rotary washing by using deionized water, and blow-drying the surface of the wafer by using nitrogen.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor material technology, and in particular to a cleaning method for improving the 19nm particle level of a 12-inch wafer. Background Art

[0002] With the continuous advancement of semiconductor technology and the shrinking of chip process nodes, the requirements for wafer surface cleanliness are becoming increasingly stringent. The 19nm process node on 12-inch wafers is particularly sensitive to particle contamination. Even tiny particles can cause device failure and affect product yield. Traditional cleaning processes are unable to meet the particle control requirements of the 19nm process. Therefore, developing a cleaning process that can effectively improve the particle level on 12-inch wafers at 19nm is of great significance. Summary of the Invention

[0003] The purpose of the present invention is to overcome the shortcomings of the background technology and provide a cleaning process method to improve the 19nm particle level of 12-inch wafers. This method can effectively remove particles on the surface of the wafer, improve the cleanliness of the wafer surface, and thus improve the product yield.

[0004] The technical solution of the present invention is: A cleaning method for improving the 19nm particle level of a 12-inch wafer comprises the following steps: Step 1. Pre-cleaning: Place the wafer in a pre-cleaning tank and use an alkaline solution containing a surfactant to pre-clean it to remove most particles and organic contamination on the wafer surface. Step 2. SC1 cleaning: Place the pre-cleaned wafer in the SC1 cleaning tank and clean it with a mixture of ammonia, hydrogen peroxide, and deionized water to remove microparticles and metal impurities on the wafer surface. Step 3. SC2 cleaning: Place the wafers cleaned in SC1 into the SC2 cleaning tank and clean them with a mixture of hydrochloric acid, hydrogen peroxide, and deionized water to remove metal impurities and the natural oxide layer on the wafer surface. Step 4. DHF cleaning: Place the wafer after SC2 cleaning in a DHF cleaning tank and clean it with a diluted hydrofluoric acid solution to remove the natural oxide layer on the wafer surface; Step 5. Megasonic cleaning: Place the wafers after DHF cleaning in a megasonic cleaning tank and use deionized water for megasonic cleaning. The cavitation effect of the megasonic waves removes particles with strong adhesion to the wafer surface. Step 6. Spin rinse and dry: Place the wafer after megasonic cleaning in a spin rinse dryer, spin rinse with deionized water, and blow dry the wafer surface with nitrogen.

[0005] Preferably, in step 1, the alkaline solution is a mixed solution of ammonia water and hydrogen peroxide, with a pH value of 9-11, a temperature of 50-70° C., and a cleaning time of 5-10 minutes.

[0006] Preferably, in step 2, the volume ratio of ammonia water, hydrogen peroxide and deionized water in the SC1 solution is 1:1:5-1:2:10, the temperature is 60-80° C., and the cleaning time is 10-15 minutes.

[0007] Preferably, in step 3, the volume ratio of hydrochloric acid, hydrogen peroxide and deionized water in the SC2 solution is 1:1:6-1:2:12, the temperature is 60-80° C., and the cleaning time is 10-15 minutes.

[0008] Preferably, in step 4, the volume ratio of hydrofluoric acid to deionized water in the DHF solution is 1:50-1:100, the temperature is 20-25° C., and the cleaning time is 1-2 minutes.

[0009] Preferably, in step 5, the frequency of the megasonic wave is 1 MHz-2 MHz, the power is 100 W-200 W, and the cleaning time is 5-10 minutes.

[0010] Preferably, in step 6, the rotational flushing speed is 1000-2000 rpm, the flushing time is 5-10 minutes, the nitrogen flow rate is 50-100 L / min, and the drying time is 5-10 minutes.

[0011] Compared with the prior art, the present invention has the following advantages: By optimizing cleaning process parameters and combining megasonic cleaning technology, the present invention can effectively remove particles from the wafer surface and improve the cleanliness of the wafer surface, thereby improving the 19nm particle level of 12-inch wafers and improving product yield.

[0012] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. DETAILED DESCRIPTION

[0013] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below.

[0014] Example 1 The cleaning method for improving the 19nm particle level of 12-inch wafers provided in this embodiment includes the following steps: Step 1. Place the 12-inch wafer in a pre-cleaning tank and pre-clean it with a mixture of ammonia and hydrogen peroxide (pH = 10, temperature = 60°C) for 8 minutes. Step 2. Place the pre-cleaned wafer in the SC1 cleaning tank and clean it with a mixture of ammonia, hydrogen peroxide, and deionized water (volume ratio = 1:1:8, temperature = 70°C) for 12 minutes. Step 3. Place the wafer cleaned in SC1 into the SC2 cleaning tank and clean it with a mixture of hydrochloric acid, hydrogen peroxide, and deionized water (volume ratio = 1:1:8, temperature = 70°C) for 12 minutes. Step 4. Place the wafer after SC2 cleaning in a DHF cleaning tank and clean it with a diluted hydrofluoric acid solution (volume ratio = 1:80, temperature = 22°C) for 1.5 minutes. Step 5. Place the DHF-cleaned wafer in a megasonic cleaning tank and perform megasonic cleaning using deionized water at a frequency of 1.5 MHz and a power of 150 W for 8 minutes. Step 6. Place the megasonic cleaned wafer in a spin rinse dryer and perform a spin rinse with deionized water (rotation speed = 1500 rpm, rinse time: 8 minutes). Then, blow dry the wafer surface with nitrogen (nitrogen flow rate = 80 L / min, blow drying time: 8 minutes).

[0015] Example 2 The cleaning method for improving the 19nm particle level of 12-inch wafers provided in this embodiment includes the following steps: Step 1. Place the 12-inch wafer in a pre-cleaning tank and pre-clean it with a mixture of ammonia and hydrogen peroxide (pH = 9, temperature = 50°C) for 5 minutes. Step 2. Place the pre-cleaned wafer in the SC1 cleaning tank and clean it for 15 minutes using a mixture of ammonia, hydrogen peroxide, and deionized water (volume ratio = 1:2:10, temperature = 80°C). Step 3. Place the wafer cleaned in SC1 into the SC2 cleaning tank and clean it for 15 minutes using a mixture of hydrochloric acid, hydrogen peroxide, and deionized water (volume ratio = 1:2:12, temperature = 80°C). Step 4. Place the wafer after SC2 cleaning in a DHF cleaning tank and clean it with a diluted hydrofluoric acid solution (volume ratio = 1:100, temperature = 20°C) for 1 minute. Step 5. Place the DHF-cleaned wafer in a megasonic cleaning tank and perform megasonic cleaning using deionized water at a frequency of 2 MHz and a power of 200 W for 10 minutes. Step 6. Place the wafer after megasonic cleaning in a spin rinse dryer and perform a spin rinse with deionized water (rotation speed = 2000 rpm, rinse time: 10 minutes). Then, blow dry the wafer surface with nitrogen (nitrogen flow rate = 100 L / min, blow drying time: 10 minutes).

[0016] Comparison plan The 12-inch wafer is cleaned using the traditional cleaning process. The specific steps are as follows: Step 1. Place the 12-inch wafer in a pre-cleaning tank and pre-clean it with a mixture of ammonia and hydrogen peroxide (pH = 10, temperature = 60°C) for 8 minutes.

[0017] Step 2. Place the pre-cleaned wafer in the SC1 cleaning tank and clean it with a mixture of ammonia, hydrogen peroxide, and deionized water (volume ratio = 1:1:8, temperature = 70°C) for 12 minutes.

[0018] Step 3. Place the wafer cleaned in SC1 into the SC2 cleaning tank and clean it with a mixture of hydrochloric acid, hydrogen peroxide, and deionized water (volume ratio = 1:1:8, temperature = 70°C) for 12 minutes.

[0019] Step 4. Place the wafer after SC2 cleaning in a DHF cleaning tank and clean it with a diluted hydrofluoric acid solution (volume ratio = 1:80, temperature = 22°C) for 1.5 minutes.

[0020] Step 5. Place the DHF-cleaned wafer in a spin rinse dryer and perform a spin rinse with deionized water (rotation speed = 1500 rpm, rinse time: 8 minutes). Use nitrogen to blow dry the wafer surface (nitrogen flow rate = 80 L / min, blow drying time: 8 minutes).

[0021] Experimental results The particles on the surface of the wafers after cleaning in Example 1, Example 2 and the comparative example were detected using a particle detector, and the results are shown in the following table: Experimental group Number of 19nm particles (ea / piece) Technical Solution 1 10 Technical Solution 2 8 Comparison plan 50 It can be seen from the experimental results that the number of particles on the wafer surface after cleaning using the process method provided by the present invention is significantly less than that of the traditional cleaning process, indicating that the present invention can effectively improve the 19nm particle level of 12-inch wafers.

[0022] The above description is merely a preferred embodiment of the present invention. For those skilled in the art, the present invention may be modified and varied in various ways. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A cleaning method for improving the 19nm particle level of 12-inch wafers, characterized in that: The following steps are involved: Step 1. Pre-cleaning: Place the wafer in a pre-cleaning tank and use an alkaline solution containing a surfactant to pre-clean it to remove most particles and organic contamination on the wafer surface. Step 2. SC1 cleaning: Place the pre-cleaned wafer in the SC1 cleaning tank and clean it with a mixture of ammonia, hydrogen peroxide, and deionized water to remove microparticles and metal impurities on the wafer surface. Step 3. SC2 cleaning: Place the wafers cleaned in SC1 into the SC2 cleaning tank and clean them with a mixture of hydrochloric acid, hydrogen peroxide, and deionized water to remove metal impurities and the natural oxide layer on the wafer surface. Step 4. DHF cleaning: Place the wafer after SC2 cleaning in a DHF cleaning tank and clean it with a diluted hydrofluoric acid solution to remove the natural oxide layer on the wafer surface; Step 5. Megasonic cleaning: Place the wafers after DHF cleaning in a megasonic cleaning tank and use deionized water for megasonic cleaning. The cavitation effect of the megasonic waves removes particles with strong adhesion to the wafer surface. Step 6. Spin rinse and dry: Place the wafer after megasonic cleaning in a spin rinse dryer, spin rinse with deionized water, and blow dry the wafer surface with nitrogen.

2. The cleaning method for improving the 19nm particle level of 12-inch wafers according to claim 1, characterized in that: In the step 1, the alkaline solution is a mixed solution of ammonia water and hydrogen peroxide, with a pH value of 9-11, a temperature of 50-70° C., and a cleaning time of 5-10 minutes.

3. The cleaning method for improving the 19nm particle level of 12-inch wafers according to claim 1, characterized in that: In step 2, the volume ratio of ammonia water, hydrogen peroxide and deionized water in the SC1 solution is 1:1:5-1:2:10, the temperature is 60-80° C., and the cleaning time is 10-15 minutes.

4. The cleaning method for improving the 19nm particle level of 12-inch wafers according to claim 1, characterized in that: In step 3, the volume ratio of hydrochloric acid, hydrogen peroxide and deionized water in the SC2 solution is 1:1:6-1:2:12, the temperature is 60-80° C., and the cleaning time is 10-15 minutes.

5. The cleaning method for improving the 19nm particle level of 12-inch wafers according to claim 1, characterized in that: In step 4, the volume ratio of hydrofluoric acid to deionized water in the DHF solution is 1:50-1:100, the temperature is 20-25° C., and the cleaning time is 1-2 minutes.

6. The cleaning method for improving the 19nm particle level of 12-inch wafers according to claim 1, characterized in that: In step 5, the frequency of the megasonic wave is 1 MHz-2 MHz, the power is 100 W-200 W, and the cleaning time is 5-10 minutes.

7. The cleaning method for improving the 19nm particle level of 12-inch wafers according to claim 1, characterized in that: In step 6, the rotational flushing speed is 1000-2000 rpm, the flushing time is 5-10 minutes, the nitrogen flow rate is 50-100 L / min, and the drying time is 5-10 minutes.