CN111334809A - Method for cleaning silver evaporation material - Google Patents

Abstract

The invention discloses a cleaning method of silver evaporation material. The cleaning method of the silver evaporating material of the present invention comprises the following steps: 1) cleaning the silver evaporating material to be cleaned using a mixed solution containing hydrogen peroxide-ammonia; 2) using the IPA solution to clean the silver evaporating material after cleaning in step 1) 3) Use pure water to clean the silver evaporation material after cleaning in step 2). The cleaning method of the silver evaporation material of the present invention can not only improve the surface quality of the silver evaporation material, but also reduce the loss of silver caused by the current cleaning method of the silver evaporation material.

Description

A kind of cleaning method of silver evaporation material

technical field

The invention relates to the technical field of cleaning processes, in particular to a cleaning method for silver evaporation materials.

Background technique

Physical vapor deposition technology (Physical Vapour Deposition, PVD for short) means that under vacuum conditions, the material source—solid or liquid surface is vaporized into gaseous atoms, molecules or partially ionized into ions by physical methods, and is passed through low-pressure gas (or plasma) The process of depositing a thin film with a special function on the surface of the substrate. The main methods of physical vapor deposition are: vacuum evaporation, sputtering coating, arc plasma coating, ion coating and molecular beam epitaxy. Among them, vacuum evaporation is widely used in the back gold process of semiconductor wafers due to its strong film bonding force, high deposition rate and uniform film thickness.

With the rapid development of artificial intelligence and 5G technology, the demand for semiconductor chips is expanding. At present, the vacuum evaporation coating technology is widely used in the back gold process of the wafer. Semiconductor chips have extremely high requirements on the purity and surface quality of their evaporation materials. Otherwise, on the one hand, defects such as Peeling and sputtering will occur during the vacuum evaporation coating process or even damage the machine; on the other hand, the performance of the film will be uneven. , which may cause the chip to be scrapped. Gold coating on the back of the wafer usually requires three metal films of Ti, Ni and Ag. Ag, as the outermost metal film, not only has the function of connecting the Ni layer, but also needs to have excellent electrical conductivity. The silver evaporation material will inevitably cause problems such as residual impurities and dirt on its surface during the preparation process. Therefore, in order to ensure the quality of the film in the wafer back gold process, the present invention provides a pure silver (purity ≥ 3N) evaporation material. The formula of the cleaning solution can not only improve the surface quality of the silver evaporation material, but also reduce the loss of silver caused by the current cleaning method of the silver evaporation material.

At present, the cleaning method of silver evaporating material is mainly centrifugal grinding, which uses the collision between evaporating materials at high speed and the washing of detergent to remove surface impurities and dirt.

CN109420638A discloses a device and a cleaning method for cleaning semiconductor equipment components, the device comprises a cleaning tank, a cleaning liquid is placed in the cleaning tank, and the components to be cleaned are immersed in the cleaning liquid in the cleaning tank; the cleaning liquid is ammonia water, Or a mixed solution of ammonia and hydrogen peroxide. The invention is based on the nitrogen-rich environment of the blue-green epitaxy process, and a large amount of ammonia gas will be used. The use of weakly alkaline ammonia water to clean the stainless steel parts will not affect the recovery of the epitaxy process. No damage to components. The invention adopts the mixed solution of ammonia water and hydrogen peroxide as the cleaning solution, but does not give a specific proportion, and only adopts the above-mentioned mixed solution for cleaning, and when applied to the cleaning of silver evaporation material, the cleaning is not thorough.

CN108987273A discloses a method for surface treatment of silver evaporation material, comprising: providing silver evaporation material; performing centrifugal grinding operation on the silver evaporation material; after the centrifugal grinding operation, cleaning the silver evaporation material; After the cleaning operation, the silver evaporation material is dried. The invention performs centrifugal grinding operation on the silver evaporation material to remove the oxide layer on the surface of the silver evaporation material and achieves the effect of surface polishing. Compared with the scheme of removing the oxide layer by pickling operation, the invention can avoid the consumption of the pickling solution The problem of the silver evaporation material, so as to improve the surface brightness and smoothness of the silver evaporation material, improve the purity of the silver evaporation material, reduce the consumption of the silver evaporation material, and then reduce the silver evaporation material preparation cost. However, this physical cleaning method will cause a lot of loss of silver evaporation material, which is not conducive to the industrial production of evaporation material.

SUMMARY OF THE INVENTION

In view of the deficiencies of the prior art, the purpose of the present invention is to provide a cleaning method for the silver evaporation material, which can not only improve the surface quality of the silver evaporation material, but also reduce the loss of silver caused by the current silver evaporation material cleaning method.

For this purpose, the present invention adopts the following technical solutions:

A cleaning method for silver evaporation material, the cleaning method comprises the following steps:

1) use the silver evaporation material to be cleaned that contains hydrogen peroxide-ammonia mixed solution to clean;

2) use IPA liquid to clean the silver evaporation material after step 1) cleaning;

3) Use pure water to clean the silver evaporation material cleaned in step 2).

The cleaning method of the silver evaporation material of the present invention first utilizes the strong oxidation of hydrogen peroxide and the dissolution of ammonia water to make residual impurities (such as Cr, Cu, Zn, Ni, Co, Ca, Fe, Mg) or oil stains on the surface of the silver evaporation material. Converted into water-soluble compounds, and then washed with IPA (isopropyl alcohol) liquid and pure water to remove water-soluble compounds, and quickly and efficiently remove impurities or oil stains that may remain on the surface of the silver evaporation material by chemical cleaning, thereby improving the silver evaporation material. Surface quality, ultimately improve the stability of the silver evaporation material during evaporation and the performance of the film, and can also reduce the loss of silver caused by the current cleaning method of the silver evaporation material.

The alkalinity of ammonia water is weak. In order to enhance the cleaning effect, hydrogen peroxide with strong oxidizing property is added, but it will not cause pollution. However, it is necessary to reasonably control the volume ratio of hydrogen peroxide and ammonia water in the hydrogen peroxide-ammonia mixture to ensure efficient and thorough removal of silver evaporation. While removing impurities and oil stains on the surface of the material, the silver evaporation material is not lost. After cleaning with hydrogen peroxide-ammonia mixture, the impurities (such as Cr, Cu, Zn, Ni, Co, Ca, Fe, Mg) or oil stains remaining on the surface of the silver evaporation material are converted into water-soluble compounds.

In step 1), the volume ratio of hydrogen peroxide and ammonia in the hydrogen peroxide-ammonia mixed solution is (1～3): (5～7), for example the volume ratio of hydrogen peroxide and ammonia is 1:5, 1:6, 1: 7, 2:5, 2:6, 2:7, 3:5, 3:6, 3:7, etc. If the volume ratio of hydrogen peroxide to ammonia water is too low, lower than 1:7, the residual impurities on the surface of the silver evaporation material cannot be completely removed. If the volume ratio of hydrogen peroxide to ammonia water is too high, higher than 3:5, the silver evaporation material There is a certain loss of raw materials.

In step 1), the cleaning is performed in an automatic rotating cleaning tank.

Wherein, the purity of silver in the silver evaporation material is ≥99.9%.

In step 1), the cleaning time is 1-3 min, for example, the cleaning time is 1 min, 1.5 min, 2 min, 2.5 min, 3 min.

In step 2), the IPA solution is cleaned, and in conjunction with the subsequent pure water cleaning, the water-soluble compounds converted into after cleaning in step 1) can be removed, and the cleaning effect can be further improved.

In step 2), the IPA liquid cleaning is ultrasonic cleaning, preferably, the ultrasonic cleaning time is 10-15 minutes, for example, the ultrasonic cleaning time is 10 minutes, 11 minutes, 12 minutes, 13 minutes, and 14 minutes. Ultrasonic cleaning combined with IPA solution can effectively improve the cleaning effect.

In step 3), the pure water cleaning time is 5-10 minutes, for example, the pure water cleaning time is 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, and 10 minutes.

The above cleaning time needs to be strictly controlled. By reasonably controlling the cleaning time, the surface quality problem of the silver evaporation material can be quickly and efficiently solved, and the loss of the silver evaporation material can be reduced on the premise of ensuring efficient impurity removal.

After the step 3), a step 4) is also included, and the silver evaporation material washed in the step 3) is dried. In step 4), the drying is vacuum drying.

In step 4), the vacuum drying temperature is 60-80°C, for example, the vacuum drying temperature is 60°C, 65°C, 70°C, 75°C, 80°C; the vacuum drying time is 60-80min, for example The vacuum drying time is 60min, 65min, 70min, 75min, 80min; the vacuum degree of the vacuum drying is below 0.01MPa.

The step 4) also includes the step of vacuum-packing the silver evaporation material after the vacuum drying.

As a preferred version of the present invention, the cleaning method of the silver evaporation material comprises the following steps:

1) putting the silver evaporating material to be cleaned into the automatic rotary cleaning tank containing hydrogen peroxide and ammonia water in the volume ratio of (1～3): (5～7) hydrogen peroxide-ammonia mixed solution and cleaning for 1～3min;

2) transfer the silver evaporation material cleaned in step 1) to the IPA liquid tank for ultrasonic cleaning for 10 to 15 minutes;

3) transfer the silver evaporation material cleaned in step 2) to a pure water tank for cleaning for 5-10 min;

4) Put the silver evaporating material cleaned in step 3) in a vacuum drying box, the vacuum degree is below 0.01 MPa, vacuum drying at 60-80° C. for 60-80 min, and vacuum packaging.

Compared with the prior art, the beneficial effects of the present invention are:

The cleaning method of the silver evaporation material of the invention can quickly and efficiently remove the impurities or oil stains remaining on the surface of the silver evaporation material, improve the surface quality of the silver evaporation material, and finally improve the stability of the silver evaporation material during evaporation and the performance of the film, It also reduces the loss of silver caused by the current silver evaporation material cleaning method.

Description of drawings

Fig. 1 is the surface quality appearance diagram of the silver evaporation material after cleaning by the cleaning method of embodiment 1;

Fig. 2 is the surface quality appearance diagram of the silver evaporation material after cleaning by the cleaning method of embodiment 2;

Fig. 3 is the surface quality appearance diagram of the silver evaporation material after cleaning by the cleaning method of embodiment 3;

Fig. 4 is the surface quality appearance diagram of the silver evaporation material after cleaning by the cleaning method of embodiment 4;

Fig. 5 is the surface quality appearance diagram of the silver evaporation material after cleaning by the cleaning method of Example 5;

Fig. 6 is the surface quality appearance diagram of the silver evaporation material after cleaning by the cleaning method of embodiment 6;

Fig. 7 is the surface quality appearance diagram of the silver evaporation material after cleaning by the cleaning method of embodiment 7;

Fig. 8 is the surface quality appearance diagram of the silver evaporation material after cleaning by the cleaning method of Comparative Example 1;

Fig. 9 is the surface quality appearance diagram of the silver evaporation material after cleaning by the cleaning method of Comparative Example 2;

Fig. 10 is the surface quality appearance diagram of the silver evaporation material after cleaning by the cleaning method of Comparative Example 3;

FIG. 11 is an appearance diagram of the surface quality of the silver evaporation material cleaned by the cleaning method of Comparative Example 4. FIG.

Detailed ways

The technical solutions of the present invention are further described below through specific embodiments.

Unless otherwise specified, various raw materials of the present invention can be purchased commercially or prepared according to conventional methods in the art.

Example 1

The cleaning method of the silver evaporation material of the present embodiment comprises the following steps:

1) putting the silver evaporating material to be cleaned into the automatic rotary cleaning tank containing hydrogen peroxide and ammonia water with a volume ratio of 1:7 and cleaning for 2min;

2) transfer the silver evaporation material after cleaning in step 1) to ultrasonic cleaning for 12min in the IPA liquid tank;

3) transfer the silver evaporation material after step 2) cleaning to pure water tank for cleaning 6min;

4) Put the silver evaporating material cleaned in step 3) in a vacuum drying box, the vacuum degree is 0.005MPa, vacuum drying at 70° C. for 60min, and vacuum packaging.

Example 2

The cleaning method of the silver evaporation material of the present embodiment comprises the following steps:

1) putting the silver evaporating material to be cleaned into the automatic rotary cleaning tank containing the hydrogen peroxide-ammonia mixed solution that the volume ratio of hydrogen peroxide and ammonia is 1:5 and cleaning for 2min;

2) transfer the silver evaporation material after cleaning in step 1) to ultrasonic cleaning for 12min in the IPA liquid tank;

3) transfer the silver evaporation material after step 2) cleaning to pure water tank for cleaning 6min;

4) Put the silver evaporating material cleaned in step 3) in a vacuum drying box, the vacuum degree is 0.005MPa, vacuum drying at 70° C. for 60min, and vacuum packaging.

Example 3

The cleaning method of the silver evaporation material of the present embodiment comprises the following steps:

1) putting the silver evaporation material to be cleaned into the automatic rotary cleaning tank containing hydrogen peroxide and ammonia water with a volume ratio of 2:7 and cleaning 2min in the hydrogen peroxide-ammonia mixed solution;

2) transfer the silver evaporation material after cleaning in step 1) to ultrasonic cleaning for 12min in the IPA liquid tank;

3) transfer the silver evaporation material after step 2) cleaning to pure water tank for cleaning 6min;

4) Put the silver evaporating material cleaned in step 3) in a vacuum drying box, the vacuum degree is 0.005MPa, vacuum drying at 70° C. for 60min, and vacuum packaging.

Example 4

The cleaning method of the silver evaporation material of the present embodiment comprises the following steps:

1) put the silver evaporation material to be cleaned into the automatic rotary cleaning tank containing hydrogen peroxide and ammonia water with a volume ratio of 3:5 for cleaning 2min in the hydrogen peroxide-ammonia mixed solution;

2) transfer the silver evaporation material after cleaning in step 1) to ultrasonic cleaning for 12min in the IPA liquid tank;

3) transfer the silver evaporation material after step 2) cleaning to pure water tank for cleaning 6min;

4) Put the silver evaporating material cleaned in step 3) in a vacuum drying box, the vacuum degree is 0.005MPa, vacuum drying at 70° C. for 60min, and vacuum packaging.

Example 5

The cleaning method of the silver evaporation material of the present embodiment comprises the following steps:

1) put the silver evaporation material to be cleaned into the automatic rotary cleaning tank containing hydrogen peroxide and ammonia water with a volume ratio of 3:5 for cleaning 2min in the hydrogen peroxide-ammonia mixed solution;

2) transfer the silver evaporation material after cleaning in step 1) to ultrasonic cleaning for 15min in the IPA liquid tank;

3) transfer the silver evaporation material after step 2) cleaning to pure water tank for cleaning 8min;

4) Put the silver evaporating material cleaned in step 3) in a vacuum drying box, the vacuum degree is 0.008MPa, 65°C vacuum drying for 80min, and vacuum packaging.

Example 6

The difference between this example and Example 1 is that the volume ratio of hydrogen peroxide to ammonia water is 1:10, and the others are the same as Example 1.

Example 7

The difference between this example and Example 1 is that the volume ratio of hydrogen peroxide to ammonia water is 1:1, and the others are the same as Example 1.

Comparative Example 1

The difference between this embodiment and embodiment 1 is that only IPA cleaning, pure water washing and vacuum drying are used, without the hydrogen peroxide-ammonia mixed solution cleaning in step 1), other are the same as embodiment 1.

Comparative Example 2

The difference between this example and Example 1 is that, in step 1), it is only cleaned with ammonia water without hydrogen peroxide, and the others are the same as in Example 1.

Comparative Example 3

The difference between this example and Example 1 is that there is no IPA liquid cleaning in step 2). Others are the same as Example 1.

Comparative Example 4

The difference between this example and Example 1 is that there is no vacuum drying in step 4), and the others are the same as Example 1.

The silver evaporation material is cleaned by the cleaning method of Examples 1-7, and the surface quality of the cleaned silver evaporation material is shown in Figures 1-7 respectively.

The silver evaporation material is cleaned by the cleaning method of Comparative Examples 1-4, and the surface quality of the cleaned silver evaporation material is shown in Figures 8-11, respectively.

As can be seen from Figures 1-5, the surface of the silver evaporation material cleaned by the cleaning method of the present invention is clean, free of impurities or oil stains, and as can be seen from Figures 6 and 7, if the volume ratio of hydrogen peroxide and ammonia is too large or too large Small, the oil stains on the surface of the silver evaporation material cannot be removed.

As can be seen from Figures 8-11, Comparative Examples 1-4 lack any step in the cleaning method of the present invention, and cannot effectively and completely remove the oily impurities on the surface of the silver evaporation material.

The present invention illustrates the detailed process equipment and process flow of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed process equipment and process flow, that is to say, it does not mean that the present invention must rely on the above-mentioned detailed process equipment and process flow to be implemented. . Those skilled in the art should understand that any improvement of the present invention, the equivalent replacement of each raw material of the product of the present invention, the addition of auxiliary components, the selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims (10)

1. The method for cleaning the silver evaporation material is characterized by comprising the following steps of:

1) cleaning the silver evaporation material to be cleaned by using a mixed solution containing hydrogen peroxide and ammonia water;

2) cleaning the silver evaporation material cleaned in the step 1) by using IPA liquid;

3) cleaning the silver evaporation material cleaned in the step 2) by using pure water.

2. The cleaning method according to claim 1, wherein in the step 1), the volume ratio of the hydrogen peroxide to the ammonia water in the hydrogen peroxide-ammonia water mixed solution is (1-3) to (5-7).

3. The cleaning method according to claim 1 or 2, wherein in step 1), the cleaning is performed in an automatic rotary cleaning tank;

preferably, the purity of the silver evaporation material is more than or equal to 99.9 percent.

4. The cleaning method according to any one of claims 1 to 3, wherein in the step 1), the cleaning time is 1 to 3 min.

5. The cleaning method according to any one of claims 1 to 4, wherein in the step 2), the IPA liquid cleaning is ultrasonic cleaning, and the time of the ultrasonic cleaning is 10-15 min.

6. The cleaning method according to any one of claims 1 to 5, wherein in the step 3), the time for cleaning with pure water is 5 to 10 min.

7. The cleaning method according to any one of claims 1 to 6, further comprising a step 4) after the step 3), wherein the silver evaporation material cleaned in the step 3) is dried.

8. The cleaning method according to claim 7, wherein in the step 4), the drying is vacuum drying;

preferably, the temperature of the vacuum drying is 60-80 ℃, the time of the vacuum drying is 60-80 min, and the vacuum degree of the vacuum drying is below 0.01 MPa.

9. The cleaning method according to claim 7 or 8, characterized in that the step 4) of vacuum drying further comprises the step of vacuum packaging the silver evaporation material.

10. A cleaning method according to any one of claims 1-9, characterized in that the cleaning method comprises the steps of:

1) putting the silver evaporation material to be cleaned into an automatic rotary cleaning tank containing hydrogen peroxide-ammonia water mixed liquid with the volume ratio of hydrogen peroxide to ammonia water being (1-3) to (5-7) for cleaning for 1-3 min;

2) transferring the silver evaporation material cleaned in the step 1) into an IPA liquid tank for ultrasonic cleaning for 10-15 min;

3) transferring the silver evaporation material cleaned in the step 2) into a pure water tank for cleaning for 5-10 min;

4) putting the silver evaporation material cleaned in the step 3) into a vacuum drying oven, performing vacuum drying for 60-80 min at the temperature of 60-80 ℃ and under the vacuum degree of below 0.01MPa, and performing vacuum-pumping packaging.

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