JPH05323580A - Cleanzing method for surface of chromium board - Google Patents

Abstract

PURPOSE:To remove particles without oxidation of chrome by forming in advance the liquid film of a neutral detergent on the surface of a board and rubbing the surface of the board through the liquid film by a sponge. CONSTITUTION:The liquid film of a neutral detergent liquid is formed in advance on the surface of a smooth board which has chrome on the surface, and particles are removed without oxidation of chrome by rubbing the surface of the board by a sponge through the liquid film. For a method for forming the liquid film of a neutral detergent liquid on the surface of a chrome board, a method for supplying a detergent liquid from the center of a board with a board being rotated by a spin-coater and the like, a method for continuously spraying a detergent liquid uniformly on the whole surface of a fixed board with shower and the like are available. For the surface active agent capable of being used for the detergent, for example, an addition product of alkylphenolethylene oxide, a nonionic surface active agent of aliphatic alkanol amide and the like and alkylether sulfuric ester salt and the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaning a smooth substrate surface having chromium on the surface, the surface of which is contaminated by particles.

[0002]

2. Description of the Related Art A smooth substrate having chromium on its surface, such as a chromium sputtered quartz plate or a chromium sputtered silicon wafer, is used in the field of semiconductor manufacturing or its related fields, for example, as a substrate for producing a photomask, and the like. ,
Use of the pellicle film as a substrate for producing a pellicle film has been proposed because of its excellent releasability between the film and the substrate after the polymer film is formed on the surface (JP-A-2-134634).

Since these are often used for microfabrication purposes, a high degree of cleanliness of the substrate surface is required, so that there is little or no particle adhesion on the substrate surface. is necessary.

Up to now, the cleaning of the substrate has been carried out in order to clean the surface of the substrate contaminated by the particles. The cleaning method at that time is generally a method including chemical cleaning with sulfuric acid and hydrogen peroxide, and ultrasonic cleaning with irradiation of ultrasonic waves of about 800 to 1000 kHz in pure water.

[0005]

However, in the conventional cleaning method, the chromium surface is oxidized during the cleaning of the substrate,
Since the amount of oxide on the surface changes, the coating thickness of the resist changes depending on the presence or absence of cleaning, and the film thickness of the substrate for producing the pellicle film also changes and the peelability between the substrate and the film decreases. As a result, there are problems in that scratches on the film surface increase, film elongation and sagging defects increase.

The present invention has been made in view of the above problems, and an object thereof is a cleaning method for removing particles adhering to a surface of a smooth substrate having chromium on its surface without oxidation of chromium. To provide.

[0007]

In order to solve the above problems, the present inventor has conducted various studies on a method for cleaning a smooth substrate having chromium on its surface. As a result, it was found that particles can be removed without oxidation of chromium by forming a liquid film of a neutral detergent solution on the surface of the chromium substrate in advance and rubbing the surface of the substrate with a sponge through the liquid film. ,
The present invention has been completed. That is, the present invention forms a liquid film of a neutral detergent solution in advance on the surface of a smooth substrate having chromium on the surface, and rubs the substrate surface with a sponge through the liquid film to prevent chromium oxidation. Par
This is a method for cleaning the surface of a chromium substrate, which is characterized by removing the tickle.

The present invention will be described in more detail below.

According to the cleaning method of the present invention, a liquid film of a neutral detergent liquid is previously formed on the surface of a chromium substrate, and the surface of the substrate is rubbed with a sponge through the liquid film.

Even if the neutral detergent liquid is used, if the liquid film is not formed and the surface is rubbed without passing through the liquid film, the particles on the surface of the substrate are not removed, and the surface of the substrate is more firmly fixed. It will stick. The detergent liquid is used after removing the particles in the liquid with a filter. Further, the method of rubbing the substrate in the detergent liquid is not preferable because recontamination from the liquid occurs.

Here, the fact that the liquid film of the neutral detergent solution is formed on the surface of the chromium substrate means that the entire surface of the chromium substrate is covered with the neutral detergent solution supplied thereon.

As a method of forming a liquid film of the neutral detergent solution on the surface of the chromium substrate, the substrate is rotated by a device such as a spin coater and the detergent solution is supplied from the center of the substrate, or the detergent is fixed on the substrate by a shower. Examples include a method of continuously spraying the liquid onto the entire surface. In order to make the liquid film always exist on the surface of the substrate during rubbing, it is preferable that the substrate is rotated by the same device as the spin coater and the detergent liquid is constantly supplied from the center of the substrate.

The detergent liquid used in the present invention is not particularly limited as long as it is neutral in the pH range of 6.0 to 8.0 in order to prevent oxidation of the chromium surface. It is preferable that the pH is within the range of 6.8 to 7.2 in order to completely eliminate the oxidation in the case of immersing in water for a long time. The concentration of the detergent in the detergent liquid is not particularly limited as long as a liquid film can be formed on the chromium surface substrate, but is 0.1% or less for ease of removal during rinsing after washing.
-5% is preferable.

The surfactant that can be used in the detergent is not particularly limited as long as it has the above-mentioned liquidity and can form a liquid film on the chromium substrate, and examples thereof include alkylphenol ethylene oxide adducts and aliphatic compounds. Nonionic surfactants such as alkanolamides, anionic surfactants such as alkyl ether sulfate ester salts and alkylbenzene sulfonates, cationic surfactants such as quaternary ammonium salts, amino acid amphoteric amphoteric and bedaiic acid amphoteric amphoteric Examples thereof include amphoteric surfactants such as and the like, or a mixture thereof. Among these, nonionic surfactants, anionic surfactants, or two of these are used for the ease of forming a liquid film on a substrate. It is preferable to use the alkyl ether sulfate ester salt because of its ease of removal during rinsing after washing. Fatty alkanol - mixed use of Ruamido is preferred.

The scrubbing material used in the cleaning of the present invention is not particularly limited as long as it is a sponge, but in order to suppress dust generation from the scrubbing material during cleaning to a small amount, a scrubbing material particularly used for a clean room is preferable. Preference is given to using. When a cloth or a brush is used as the scrubbing material, some portions are rubbed without passing through the detergent liquid film, and defective particle removal is likely to occur.

In the cleaning of the present invention, it is necessary to rub through the surface of the neutral detergent solution. The particles cannot be sufficiently removed only by immersing in the detergent solution and spraying the detergent solution onto the surface without rubbing. Also, ultrasonic cleaning,
Particles can be removed when high-pressure jet cleaning is performed, but this is not preferable because oxidation of the chromium surface is involved.

[0017]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 Diameter 7 sputtered with chromium to a thickness of 0.07μ
The inch quartz glass substrate was left outside the clean room and a large amount of dust adhered to the surface. Next, in a clean room of Class 100, the substrate was set on a spin coater and rotated at 200 rpm, and 0.2% of a 1% aqueous solution of a neutral detergent (Kao's trade name: Family Fresh) was added. After filtering with a filter, a liquid film of the detergent liquid was formed at the center of the substrate at a flow rate of 50 ml / min and a liquid film of the detergent liquid was formed on the entire surface of the substrate. Place Kanebo's product name: BERKLIN) on the center of the board, and repeat the movement from the board center to the outer circumference.
I rubbed for a minute. After that, the removal of the sponge from the substrate was stopped, the detergent was only dropped on the rotating substrate for 1 minute, and then ultrapure water was dropped at the center of the substrate for 3 minutes at a flow rate of 50 ml / min. Dried.

As a result of inspecting 20 substrates subjected to this treatment under irradiation of a halogen lamp, the average number of particles confirmed on one surface was 0.2.
Also, the same substrate was subjected to Auger electron spectroscopy analysis to analyze the depth from the substrate surface to a depth of 80 Å, and the intensity ratio of oxygen peak and chrome peak was measured at intervals of 10 Å. I asked. This value was the same at each depth as the substrate not subjected to the cleaning treatment, which was obtained by the same analysis.

Example 2 Diameter 7 sputtered with chromium to a thickness of 0.07μ
The inch quartz glass substrate was left outside the clean room and a large amount of dust adhered to the surface. Next, in a class 100 clean room, the substrate was set on a spin coater and rotated at 200 rpm, and 1% of a nonionic detergent (Nikko Chemicals trade name: NIKKOL NP-10) was used.
After filtering the aqueous solution with a 0.2 μ filter, the flow rate is 5
A liquid film of the detergent liquid was dropped onto the substrate surface at 0 ml / min to form a liquid film on the entire surface of the substrate.
A room sponge (Kanebo's trade name: Bellclin) was placed on the center of the substrate and rubbed for 3 minutes by repeating the movement from the center of the substrate to the outer periphery. After that, stop removing the sponge from the substrate and only drop the detergent on the rotating substrate for 1 minute.
After adding ultrapure water to the center of the substrate for 3 minutes at a speed of / min, the substrate was dried.

As a result of inspecting 20 substrates subjected to this treatment under irradiation with a halogen lamp, the average number of particles confirmed on one surface was 0.3.
Also, the same substrate was subjected to Auger electron spectroscopy analysis to analyze the depth from the substrate surface to a depth of 80 Å, and the intensity ratio of oxygen peak and chrome peak was measured at intervals of 10 Å. I asked. This value was the same at each depth as the substrate not subjected to the cleaning treatment, which was obtained by the same analysis.

Comparative Example 1 Diameter 7 sputtered with chromium to a thickness of 0.07μ
The inch quartz glass substrate was left outside the clean room and a large amount of dust adhered to the surface. Next, in a clean room of Class 100, the substrate was set on a spin coater and rotated at 200 rpm, and 0.2% of a 1% aqueous solution of a neutral detergent (Kao's trade name: Family Fresh) was added. After filtering with a filter, it was continued to flow down to the center of the substrate for 10 minutes at a flow rate of 200 ml / min. The rotation and the dropping were stopped, the substrate was removed, and the substrate was immersed in an ultrapure overflow tank for 3 minutes. After the immersion, the substrate surface was pulled up and dried so that no water droplets remained on the substrate surface.

When 20 substrates subjected to this treatment were inspected under irradiation of a halogen lamp, 100 or more particles were confirmed on the surface of each of the 20 substrates.

Comparative Example 2 Chromium sputtered to a thickness of 0.07μ has a diameter of 7
The inch quartz glass substrate was left outside the clean room and a large amount of dust adhered to the surface. Next, in a clean room of Class 100, the substrate was set on a spin coater, and a 1% aqueous solution of a neutral detergent (Kao's trade name: Family Fresh) of 0.2 μ was placed on the spin coater without rotation. After filtering with a filter, the solution was dropped onto the center of the substrate at a flow rate of 50 ml / min. The substrate surface repelled the detergent liquid, and some portions were covered with the liquid film and some were not. In this state, a clean room sponge moistened with ultrapure water (Kanebo's trade name: Bellclin) was placed on the center of the substrate and rubbed for 3 minutes by repeating the movement from the center of the substrate to the outer periphery. Then, after stopping removing the sponge from the substrate, the substrate is rotated at 200 rpm and only the detergent is dropped on the rotating substrate for 1 minute.
Subsequently, ultrapure water was dropped at the center of the substrate for 3 minutes at a flow rate of 50 ml / min, and then dried.

When 20 substrates subjected to this treatment were inspected under irradiation of a halogen lamp, innumerable particles were confirmed on the surface of all 20 substrates.

Comparative Example 3 Diameter 7 sputtered with chromium to a thickness of 0.07μ
The inch quartz glass substrate was left outside the clean room and a large amount of dust adhered to the surface. Next, in a clean room of Class 100, the substrate was set on a spin coater and rotated at 200 rpm, and 0.2% of a 1% aqueous solution of a neutral detergent (Kao's trade name: Family Fresh) was added. After filtering with a filter, a liquid film of the detergent liquid was dropped onto the center of the substrate at a flow rate of 50 ml / min to form a liquid film of the detergent liquid on the entire surface of the substrate, and then the cleaning cloth for clean room (wet with ultrapure water) ( Kanebo's product name: Sabina Minimax) was placed on the center of the substrate and rubbed for 3 minutes by repeating the movement from the center of the substrate to the outer periphery. Then, stop removing the cloth from the substrate, drop the detergent only on the rotating substrate for 1 minute, and then continuously drop ultrapure water on the substrate center for 3 minutes at a flow rate of 50 ml / min. Dried.

When 20 substrates subjected to this treatment were inspected under irradiation with a halogen lamp, innumerable particles were confirmed on the surface of all 20 substrates.

Comparative Example 4 Diameter 7 sputtered with chromium to a thickness of 0.07μ
The inch quartz glass substrate was left outside the clean room and a large amount of dust adhered to the surface. Next, in a clean room of Class 100, the substrate was immersed in a cleaning bath of sulfuric acid / hydrogen peroxide solution heated to 80 ° C. for 3 minutes, and then a pure water rapid supply / drainage cleaning bath and hot pure water of 50 ° C. The sample was immersed in the overflow tank and the pure water ultrasonic cleaning tank in this order, and then dried.

As a result of inspecting 20 substrates subjected to this treatment under irradiation of a halogen lamp, the average number of particles confirmed on one surface was 1.2.

Also, the same substrate was subjected to Auger electron spectroscopic analysis to obtain a depth of 80 angstroms from the substrate surface.
And the intensity ratio between the oxygen peak and the chrome peak was determined at intervals of 10 angstroms. When compared with the value of the substrate not subjected to the cleaning treatment, which was obtained by the same analysis, an increase in the proportion of oxygen was observed at each depth.

[0031]

As is clear from the above description, according to the method of the present invention, a liquid film of a neutral detergent liquid is formed in advance on the surface of a smooth substrate having chromium on the surface, and the liquid film is interposed through the liquid film. By rubbing the surface of the substrate with a sponge, the particles can be removed without oxidation of chromium, without the problem of oxidation of the chromium surface during cleaning in the conventional cleaning method. It has the effect of cleaning the surface of the chromium substrate.

Claims (3)

[Claims] 1. A liquid film of a neutral detergent liquid is previously formed on a surface of a smooth substrate having chromium on the surface, and the liquid film is formed through the liquid film.
A method for cleaning a surface of a chromium substrate, which comprises rubbing the surface of the substrate with a sponge to remove the particles without oxidizing the chromium. 2. The method for cleaning a surface of a chromium substrate according to claim 1, wherein the pH of the neutral detergent solution is in the range of 6.0 to 8.0. 3. The method for cleaning a surface of a chromium substrate according to claim 1, wherein the neutral detergent liquid component contains an alkyl ether sulfate ester salt and a fatty acid alkanolamide.