CN101152652B - Method for cleaning surface of anodize parts - Google Patents

Abstract

The method for cleaning the surface of anodized parts according to the present invention, its core is to first clean the surface of the parts with an organic solvent; then use an alkaline solution and an acidic solution to clean the surface of the parts in sequence; finally, use ultrasonic waves to clean the parts. To achieve the purpose of removing deposits on the surface of parts. This method is a non-destructive, simple and effective method for cleaning the anodized surface. It mainly includes the use of organic solvents, alkaline solutions, diluted acidic solutions and ultrasonic cleaning to remove pollutants on the anodized surface. The method will not peel off the anodized layer, and if there is any damage, it will be extremely small, and will not cause the parts to need to be re-anodized.

Description

A cleaning method for the surface of anodized parts

technical field

The invention relates to a method for cleaning objects, in particular to a method for cleaning the surface of anodized parts.

Background technique

With the development of semiconductor chip technology, the technology node has developed from 250nm to 65nm, or even below 45nm, and the size of silicon wafers has also increased from 200mm to 300mm. Under such circumstances, the cost of each silicon wafer becomes higher and higher . The technological requirements for processing silicon wafers are becoming more and more stringent. The processing of semiconductors needs to go through multiple processes, including deposition, photolithography, etching, etc. The etching process is one of the more complicated ones. The state of the plasma and various process parameters during the plasma etching process are related to the etching results. D.

When the etching machine is performing a normal etching process, products in the etching process will be deposited on the surface of the parts in the etching reaction chamber of the etching machine. As the etching process continues for a certain number of RF hours, when the amount of deposits inside the etching reaction chamber reaches a certain level, the process state of the etching reaction chamber will change greatly, resulting in etching rate drift and decrease in etch uniformity. At this time, the process state of the etching reaction chamber can no longer meet the process standards of the product. The parts in the etching reaction chamber must be processed to remove the pollutants on the surface and restore the normal process conditions of the etching reaction chamber, so as to meet Equipment owner's production requirements.

The usual cleaning method is to use HNO3 + HF to soak and then use emery paper to clean. During the cleaning process, because the characteristics of the surface of anodized parts are different from those of other metal parts, this method is not only time-consuming and labor-intensive in the process of removing polymers, but also easily damages the surface of anodized parts, and the cleaning effect on polymers is not good. Very good, with dark gray stains remaining.

The etching reaction chamber is usually made of anodized aluminum. The polycrystalline etching anodized parts we refer to here refer to the anodic oxidation in the process chamber for plasma etching the polysilicon layer on the silicon wafer. These anodized parts are in direct contact with the process chamber, and impurities in various processes are easily deposited on their surfaces, and cannot be pumped away from the pumping chamber. However, the pollutants deposited on the surface of the anodized layer will continuously release various impurity particles during the process, which will affect the stability of the process and lead to the increase of particles on the surface of the silicon wafer. However, anodic oxidation usually only forms a very thin aluminum oxide layer on the surface of the aluminum material. A slight carelessness in the cleaning process may cause the aluminum oxide layer to be damaged or fall off, causing the parts to be scrapped.

Contents of the invention

The purpose of the present invention is to provide a cleaning method for the surface of anodized parts, which can realize the wet cleaning of the surface of anodized parts, has little damage to the surface of the parts, and fully meets the requirements of use.

The purpose of the present invention is achieved through the following technical solutions:

A method for cleaning the surface of anodized parts, comprising the following steps:

A. Clean the surface of the parts with organic solvents;

B. Use alkaline solution and acid solution to clean the surface of parts in sequence;

C. Clean the parts with ultrasonic waves.

Described step A comprises:

A1. Wipe the parts with an organic solvent until no colored impurities fall off;

A2. Use the organic solvent to spray the parts for the set spraying time, which can be repeated multiple times, and each time the spraying time can be the same or different from the organic solvent used; and/or,

A3. Soak the parts with organic solvent for the set soaking time, which can be repeated many times, and each time the soaking time can be the same or different from the organic solvent used.

Said Step A also includes after wiping, spraying and/or immersing the parts for cleaning:

A4. Dry the surface of the part with clean high-pressure air; and/or,

A5. Wipe the parts with a clean wipe until no colored impurities fall off.

Described organic solvent is:

Isopropanol, 100%, per SEMI Standard C41-1101A, Class I; or,

Acetone, compliant with electronically pure grade.

Described step B includes in no particular order:

B1. Wipe the parts with acid solution, not exceeding the set wiping time;

B2. Soak the parts with alkaline solution for the set cleaning time;

Said step B also includes after wiping and/or immersing the parts for cleaning:

B3. Spray the parts with an organic solvent for the set cleaning time, which can be repeated multiple times, and each time the cleaning time can be the same or different from the organic solvent used; and/or,

B4. Dry the surface of the parts with clean high-pressure gas.

Described acid solution is:

HF:HNO ₃ :H ₂ O is 0.1～2:5:50);

or,

Described alkaline solution is:

The ratio of NH ₄ OH: _{H 2} O ₂ : _{H 2} O is 0.5 to 3:2:5.

Described step C comprises:

Place the part in an ultrasonic bath containing an organic solvent and clean for the set time.

The method described:

Before cleaning include:

Provide a protective layer on the surface of the part that has not been anodized,

Before step C include:

Remove the protective layer on the surface of the part that has not been anodized.

It can be seen from the above-mentioned technical solution provided by the present invention that the core of the method for cleaning the surface of anodized parts in the present invention is to first clean the surface of the part with an organic solvent; surface; finally, parts are cleaned ultrasonically. To achieve the purpose of removing deposits on the surface of parts. This method is a non-destructive, simple and effective method for cleaning the anodized surface. It mainly includes the use of organic solvents, alkaline solutions, diluted acidic solutions and ultrasonic cleaning to remove pollutants on the anodized surface. The method will not peel off the anodized layer, and if there is any damage, it will be extremely small, and will not cause the parts to need to be re-anodized.

Detailed ways

The method for cleaning the surface of anodized parts according to the present invention, its core is to first clean the surface of the parts with an organic solvent; then use an alkaline solution and an acidic solution to clean the surface of the parts in sequence; finally, use ultrasonic waves to clean the parts. To achieve the purpose of removing deposits on the surface of parts.

Before cleaning with this method, we used scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) to analyze the anodized surface to be cleaned, and found that the deposits on the anodized surface of the chamber parts that have been used for a period of time ( Pollutants) mainly include: organic impurities, metal impurities, electrode impurities, silicon impurities, fluoride impurities, surface particles. In detail, for example, fluoride impurities in pollution include AlF, TiF, etc.; metal impurities include Fe, Cr, Ni, Mo, V, Cu, etc.; electrode impurities include W, P, etc.; silicon particles include Si, SiO2 wait.

Described cleaning method specifically comprises:

1. The process of cleaning the surface of parts with organic solvents

Can contain the following methods or combinations thereof:

1. Wipe the parts with an organic solvent until no colored impurities fall off; usually use a dust-free cloth dipped in an organic solvent to wipe the parts until there is no color on the dust-free cloth.

2. Use an organic solvent to spray the set spraying time of the parts, which can be repeated multiple times, and the spraying time can be the same or different from the organic solvent used; usually the organic solvent is used to directly spray the surface of the oxide layer of the parts , not less than the set spraying time, then dry the surface of the parts with clean high-pressure gas or wipe the parts with a clean dust-free cloth until there is no color on the dust-free cloth.

3. Soak the parts with organic solvent for the set soaking time, which can be repeated many times, and each soaking time can be the same or different from the organic solvent used. Usually use organic solvent to directly soak the parts, not less than the set soaking time, and then wipe the parts with a clean dust-free cloth until there is no color on the dust-free cloth or dry the parts with clean high-pressure air.

The dust-free cloth is the wiper mentioned above, which needs to meet the use standards of the ultra-clean room. Comply with CL4 (Class 100 clean room) requirements, and wipe pads can also be used as wipes, which must meet the semiconductor industry standards. Comply with CL4 (Class 100 clean room) requirements.

The organic solvent here is:

Isopropanol, 100%, meets Class I standard of SEMI standard C41-1101A; of course, other organic solvents can also be used.

or use:

Acetone, in line with electronic purity requirements.

Electronic pure is a grade of chemical reagents in the national standard, referred to as MOS grade, and its content of electrical impurities is extremely low.

2. Use alkaline solution and acid solution to clean the surface of parts in sequence

What needs to be clear here is that it can be cleaned with an alkaline solution first and then with an acidic solution. It is best to wash with an acidic solution first and then with an alkaline solution.

1. The cleaning method of acid solution is to use a dust-free cloth (wiping pad can also be used) dipped in acid solution to wipe the parts and do not exceed the set wiping time;

After this process is over, in order to enter the next process, it is usually necessary to spray the surface of the oxide layer of the part directly with an organic solvent, not less than the set spraying time, and then dry the surface of the part with clean high-pressure gas.

2. Soak the parts with alkaline solution for the set cleaning time; usually use alkaline solution to soak the parts directly, not less than the set soaking time, and then wipe the parts with a clean dust-free cloth until there is no dust on the cloth. color so far.

After this process is over, in order to enter the next process, it is usually necessary to spray the surface of the oxide layer of the part directly with an organic solvent, not less than the set spraying time, and then dry the surface of the part with clean high-pressure gas.

The formula for the acidic solution here is:

HF:HNO ₃ :H ₂ O is 0.1～2:5:50;

Its preferred formula is:

HF:HNO ₃ :H ₂ O is 1:5:50;

or,

The formula of the alkaline solution here is:

NH ₄ OH: _{H 2} O ₂ : _{H 2} O is 0.5～3:2:50;

Its preferred formula is:

The ratio of NH ₄ OH: _{H 2} O ₂ : _{H 2} O is 1:1:2.

3. Use ultrasonic cleaning parts

Place the part in an ultrasonic bath containing an organic solvent and clean for the set time.

In addition, in order to protect the non-oxidized surface of the part, a protective layer must be provided on the surface of the part that has not been anodized before cleaning, that is, a tape that is resistant to chemical corrosion; after cleaning, it is necessary to remove the surface of the part that has not been anodized. The protective layer is set on the surface, that is, the tape that resists chemical and cultural corrosion is peeled off.

Visible, basic cleaning method of the present invention is:

Step 1. Use isopropyl alcohol (IPA: 100%, conforming to SEMI standard C41-1101A, grade 1 or better) to remove organic impurities on the anodized surface. Other organic solvents can also be used if they meet the requirements, but only if they cannot Cause recontamination of anodized parts.

Step 2. Use alkaline solution NH ₄ OH (ammonia water, 29%, meet SEMI standard C21-0301, grade 1 or better) + H ₂ O ₂ (hydrogen peroxide, 29%, meet SEMI standard C31-1101, 1 grade or better) to clean anodized surfaces. This alkaline solution removes organic impurities, metallic impurities and fluoride. H2O2 is a strong oxidizing agent, which can oxidize metal impurities into high-priced metal ions, and metal ions can be removed by forming stable complex ions with ammonia water. For example, Cu is oxidized by H ₂ O ₂ to Cu+, and then Cu+ and ammonia water form Cu+(NH ₃ ) ₄ ²⁺ . This alkaline solution works well above 50°C.

Step 3. Use acidic solution HF (hydrofluoric acid, 49%, comply with SEMI standard C28-0301, grade 1 or better) + HNO ₃ (nitric acid, 67%, comply with SEMI standard C35-0301, grade 1 or better) To clean the anodized surface consists of HF (49%, comply with SEMI standard C28-0301, Gradel or better) + HNO ₃ (67%, comply with SEMI standard C41-1101A, Gradel or better). _HNO3 in this acidic solution can remove metal particles and electrode impurities, and HF can remove silicon particles, for example, react with silicon dioxide _SiO2 as follows:

4HF+SiO ₂ ＝SiF ₄ +2H ₂ O

6HF+SiO ₂ ＝H ₂ SiF ₆ +2H ₂ O

The concentration of H+ and F- in this acidic solution is low, so he has a low reaction constant (K1=1.3×10-3mol/l), HNO ₃ can decompose H+, so the content of HNO ₃ can lead to even lower F-concentration. Because HF can attack ceramic grain boundaries, special care must be taken when using HF to treat the surface of ceramic materials (anodized alumina is a ceramic material). An increase in the concentration of _HNO3 during the cleaning process was considered to enhance the removal of metals and metal ions. As a strong oxidizing acid, HNO ₃ can react with active metals, such as Fe, Ni, Al, Zn, and also react with inactive metals such as Cu.

When using the solution mentioned above to wipe the local stains on the surface of ESC ceramics, using a wiping pad (such as 3MTM CE2200) can help remove the pollutants on the anodized surface.

As mentioned above, step 2 and step 3 can be interchanged.

Step 4. Ultrasonic cleaning. This process can not only remove the Particles on the anodized surface, but also remove the Particles inside some holes of the anodized parts. For example, air extraction holes in the lining. After ultrasonic cleaning, it is our hope that the particle density of 0.3μm particles on the parts is less than 5Particle/cm2.

There are several solutions for cleaning the surface of anodized parts by this method. Here are two examples of cleaning by this method, but this method is not limited to the following examples:

Embodiment one:

Step 11. First, use anti-chemical corrosion tape to protect the surface of the anodized parts that has not been anodized and will react with the chemical solution used in the cleaning process.

Step 12. Spray the surface of the anodized layer with ultrapure water UPW (resistivity ≥ 18Ω/cm, 25°C) for at least 5 minutes, and then dry the surface of the component with an N2 gun with a filter (0.05-0.1μm).

Step 13. Wipe the surface of the dried anodized layer with a dust-free cloth dipped in isopropanol until there is no color on the dust-free cloth.

Step 14. Soak the anodized surface in 80°C UPW for 1 hour, and then wipe the anodized surface with a dust-free cloth.

Step 15. Soak the parts in 6% H ₂ O ₂ for 30mins, and then wipe the surface of the ESC with a dust-free cloth. If necessary, local stains on the surface of the anodized layer were wiped with a wiping pad (3MTM CE2200).

Step 16. Spray the parts with UPW (resistivity≥18Ω/cm, 25°C) for at least 5mins, and then dry the surface of the parts with a nitrogen _N2 gun with a filter (0.05-0.1μm).

Step 17. Wipe the surface of the anodized part with a dust-free cloth dipped in HF:HNO ₃ :H ₂ O (1:5:50). The longest wiping time should never exceed 30 seconds. Wiping pads (3MTM CE2200) can also be used to wipe the surface of the part.

Step 18. Use UPW (impedance resistance ≥ 18Ω/cm, 25°C) to spray the parts for at least 10mins. When spraying, pay attention to cleaning the holes and some grooves, and then use a filter (0.05-0.1μm) with N ₂ guns to dry the surface of the parts.

Step 19. Soak the parts in NH ₄ OH: _{H 2} O ₂ :H ₂ O (1:1:2) for 20mins, and wipe them with a dust-free cloth or a cleaning pad (3MTM CE2200).

Step 110. Use UPW (impedance resistance ≥ 18Ω/cm, 25°C) to spray the surface of the parts for at least 5mins. When spraying, pay attention to the cleaning of He pores and some grooves, and then use a filter (0.05-0.1μm) Dry the surface of the parts with an _N2 gun.

Step 111, then move the ESC to a class 1000 clean room and measure the roughness of the ESC ceramic surface (such as a pocket-sized EMD-1500-311 surface roughness tester)

Step 112, put the ESC into an ultrasonic tank with UPW and ultrasonically clean it for 60 mins (at room temperature). In the process of ultrasonic cleaning, the anodized surface must not come into contact with the bottom of the ultrasonic tank

Step 113. Remove the chemical-resistant tape on the surface of the component, wipe the surface protected by the chemical-resistant tape with IPA, and then rinse with IPA

Step 114 , blow dry the surface of the part, including holes and grooves on the surface of the part, with an N2 supply device.

Step 115. Take the part to a clean room of class 100, and then put it in a heating lamp or an oven to bake at 120°C for 2hours, and then let the part cool down slowly (cooling with the furnace) to 50-60°C. Then detect the particle size of the ESC surface (for example, use QIII+Surface Particle Detector:. QIII surface particle tester).

Embodiment two:

Step 21. First use chemical corrosion resistant tape to protect the surface of the anodized parts that has not been anodized and will react with the chemical solution used in the cleaning process.

Step 22. Spray the surface of the anodized layer with UPW (resistivity ≥ 18Ω/cm, 25°C) for at least 5mins, and then dry the surface of the parts with a _N2 gun with a filter (0.05-0.1μm).

Step 23. Soak the parts in 6% H ₂ O ₂ for 30mins, and then wipe the surface of the ESC with a dust-free cloth. If necessary, local stains on the surface of the anodized layer were wiped with a wiping pad (3MTM CE2200).

Step 24. Spray the parts with UPW (resistivity ≥ 18Ω/cm, 25°C) for at least 5mins, and then dry the surface of the parts with a _N2 gun with a filter (0.05-0.1μm).

Step 25. Soak the parts in IPA for 30mins, and then wipe the surface of the parts with a dust-free cloth. Spray the ESC with UPW (resistivity ≥ 18Ω/cm, 25°C) for at least 5mins, and then dry the surface of the part with a _N2 gun with a filter (0.05-0.1μm).

Step 26. Soak the parts in NH4OH: _{H 2} O ₂ :H ₂ O (1:1:2) for 20mins, and wipe them with a dust-free cloth or a cleaning pad (3MTM CE2200).

Step 27. Use UPW (impedance resistance ≥ 18Ω/cm, 25°C) to spray the surface of the parts for at least 5mins. When spraying, pay attention to the cleaning of He pores and some grooves, and then use a filter (0.05-0.1μm) Use an N2 gun to dry the surface of the parts.

Step 28. Wipe the surface of the anodized part with a dust-free cloth dipped in HF:HNO ₃ :H ₂ O (1:5:50). The longest wiping time should never exceed 30 seconds. Wiping pads (3MTM CE2200) can also be used to wipe the surface of the part.

Step 29. Spray the parts with UPW (resistivity ≥ 18Ω/cm, 25°C) for at least 10mins. When spraying, pay attention to cleaning the holes and some grooves, and then use N ₂ with a filter (0.05-0.1μm) The gun dries the surface of the part.

Step 210, then move the ESC to a class 1000 clean room and measure the roughness of the ESC ceramic surface (for example Fowler Pocket Surf: Fred V.Fowler Co., Inc., Newton, Mass.)

Step 211, put the ESC into an ultrasonic tank with UPW and ultrasonically clean it for 60 mins (at room temperature). In the process of ultrasonic cleaning, the anodized surface must not come into contact with the bottom of the ultrasonic tank

Step 212, remove the anti-chemical tape on the surface of the component, wipe the surface protected by the anti-chemical tape with IPA, and then rinse with IPA

Step 213 , using N2 supply device to dry the surface of the part, including holes and grooves on the surface of the part.

Step 214, take the parts to the clean room of class 100, and then put it in a heating lamp or an oven to bake at 120°C for 2 hours, and then allow the parts to cool slowly (cooling with the furnace) to 50-60°C. Then detect the particle size of the ESC surface (for example, with QIII+Surface Particle Detector: Pentagon Technologies, Livermore, Calif.).

In summary, the cleaning method described in the technical solution of the present invention is a non-destructive, simple and effective method for cleaning anodized surfaces, and it mainly includes the use of organic solvents, alkaline solutions, diluted acidic solutions and ultrasonic cleaning This method removes the pollutants on the anodized surface, which will not cause the anodized layer to peel off, and if there is any damage, it will be extremely small, and will not cause the parts to be re-anodized.

This method can not only meet the cleaning requirements of the anodized parts in the low-process process chamber, but also meet the requirements of the anodized parts in the high-process (0.25 μm) process chamber.

The traditional wet cleaning has a lot of damage to the parts themselves, but this cleaning method has almost zero damage to the parts themselves, which prolongs the service life of the parts and saves the cost of parts and consumables for the equipment owner.

This wet cleaning method saves nearly one hour compared with the traditional cleaning method of polycrystalline etching and anodized parts, and saves the labor cost of the cleaner.

This wet cleaning method saves nearly 30% of the chemical solution compared with the traditional cleaning method of polycrystalline etching and anodized parts, and saves the cost of the cleaner's chemical solution.

What are the technical key points and protection points of the present invention

This cleaning method can fully meet the requirements of anodized parts in high-process (0.25 μm) process chambers, and is the key to ensure the production of high-process processes.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed in the present invention can easily think of changes or Replacement should be covered within the protection scope of the present invention.

Claims (8)

1. A method for cleaning the surface of an anodized part, characterized in that it may further comprise the steps: A. Clean the surface of the parts with organic solvents; B. Use alkaline solution and acid solution to clean the surface of parts in sequence; C. Clean the parts with ultrasonic waves; The acidic solution is: HF:HNO ₃ :H ₂ O in a ratio of 0.1 to 2:5:50; The alkaline solution is: NH ₄ OH: _{H 2} O ₂ : _{H 2} O at a ratio of 0.5 to 3:2:5. 2. the cleaning method of anodized part surface according to claim 1, is characterized in that, described step A comprises: A1. Wipe the parts with an organic solvent until no colored impurities come off; and/or, A2. Use the organic solvent to spray the parts for the set spraying time, which can be repeated multiple times, and each time the spraying time can be the same or different from the organic solvent used; and/or, A3. Soak the parts with organic solvent for the set soaking time, which can be repeated many times, and each time the soaking time can be the same or different from the organic solvent used. 3. The method for cleaning the surface of anodized parts according to claim 2, characterized in that, said step A also includes after wiping, spraying and/or soaking the parts for cleaning: A4. Dry the surface of the part with clean high-pressure air; and/or, A5. Wipe the parts with a clean wipe until no colored impurities fall off. 4. the method for cleaning the surface of anodized parts according to claim 1 or 2, is characterized in that, described organic solvent is: Isopropanol, 100%, per SEMI Standard C41-1101A, Class I; or, Acetone, compliant with electronically pure grade. 5. the method for cleaning the surface of anodized parts according to claim 1, characterized in that, described step B comprises in no particular order: B1. Wipe the parts with acid solution, not exceeding the set wiping time; B2. Soak the parts with alkaline solution for the set cleaning time. 6. The method for cleaning the surface of anodized parts according to claim 5, characterized in that, described step B also includes after wiping and/or soaking the parts for cleaning: B3. Spray the parts with an organic solvent for the set cleaning time, which can be repeated multiple times, and each time the cleaning time can be the same or different from the organic solvent used; and/or, B4. Dry the surface of the parts with clean high-pressure gas. 7. The method for cleaning the surface of anodized parts according to claim 1, wherein said step C comprises: Place the part in an ultrasonic bath containing an organic solvent and clean for the set time. 8. the method for cleaning the surface of anodized parts according to claim 1, characterized in that: Before cleaning include: Provide a protective layer on the surface of the part that has not been anodized; After step C include: Remove the protective layer on the surface of the part that has not been anodized. the