JPH11197678A - Cleaning liquid for electronic material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce soluble impurities and to produce simply and economically by dissolving a gas purified by being contacted with pure water in advance into a cleaning liquid. SOLUTION: A gas purified by being contacted with pure water in advance is dissolved into a cleaning liquid. Besides pure water and ultrapure water, an acidic cleaning liquid in which hydrochloric acid and others are added into pure water or ultrapure water, an alkaline cleaning water containing added with ammonia and others, an oxidizing cleaning liquid added with hydrogen peroxide and others, and a reducing cleaning liquid added with a hydrogen sulfate and others are used as the cleaning liquid. Ozone, hydrogen, oxygen, carbon dioxide, chlorine, argon, and others is used as the gas to be dissolved. The gas is led to a porous plate 3 installed in the bottom part of a water bath container 2 through raw material gas piping 1 and released into pure water as bubbles. The gas in which impurities are dissolution-removed is sent through a purifying gas piping 4. A pure water inlet 5 and water outlet 6 are formed in the container 2 for the renewal of water.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cleaning liquid for electronic materials. More specifically, the present invention relates to a cleaning solution for electronic materials that dissolves gas and has a very small amount of dissolved impurities, which is used for wet cleaning of electronic materials such as silicon substrates for semiconductors, glass substrates for liquid crystals, and quartz substrates for photomasks. About.

[0002]

2. Description of the Related Art Conventionally, silicon substrates for semiconductors, glass substrates for liquid crystals, quartz substrates for photomasks, etc.
A concentrated chemical solution based on hydrogen peroxide, such as a mixture of sulfuric acid and hydrogen peroxide, a mixture of hydrochloric acid, hydrogen peroxide and water, and a mixture of ammonia water, hydrogen peroxide and water, called cleaning. It had been cleaned by the high temperature cleaning used. If this cleaning method is adopted, the cost of chemicals, the cost of ultrapure water for rinsing, the cost of waste liquid treatment, and the cost of air conditioning that exhausts chemical vapors and creates clean air will be reduced. In order to reduce the burden on the environment such as mass disposal and emission of exhaust gas, the wet cleaning process has recently been reviewed. According to the present inventors, depending on the object to be cleaned and the purpose of cleaning, hydrogen gas, oxygen, and the like are added to a cleaning liquid in which hydrochloric acid, ammonia, hydrogen peroxide, bisulfite, or the like is dissolved in ultrapure water or ultrapure water. We have developed a cleaning solution for electronic materials in which gases such as gas, carbon dioxide, chlorine gas, nitrogen gas, and rare gas are dissolved. The cleaning liquid for electronic materials in which such a specific gas is dissolved is required to have a small content of impurities, and the dissolved gas also needs to be of high purity. Solid impurities contained in the gas can be easily removed by a commercially available gas filter, but soluble metal components and organic components contained in the gas are entrained by the gas into the cleaning solution for electronic materials. Easy to mix. Means of purchasing and using commercially available high-purity gas can be considered, but high-purity gas is not always available in a situation where it can be applied,
There are also gases for which it is not possible to obtain high-purity products. For example,
Ozone is not available as a single gas or high-purity gas containing ozone in a cylinder or the like, but is produced before use by electrolysis of water or silent discharge using air or oxygen gas as a raw material. And its purity depends on the manufacturing conditions. Ozone generally has higher productivity in the silent discharge method, but is more liable to be mixed with the electrode material and is inferior in purity. Further, even in the water electrolysis method, the purity of ozone depends on the material and surface condition of the liquid contact material, and it is not easy to obtain high-purity ozone. For this reason, there has been a demand for a high-purity cleaning solution for electronic materials that can be easily and economically produced by dissolving ozone, hydrogen gas, oxygen gas, carbon dioxide gas, chlorine gas, nitrogen gas, rare gas and the like.

[0003]

DISCLOSURE OF THE INVENTION The present invention is directed to a wet cleaning of electronic materials such as a silicon substrate for a semiconductor, a glass substrate for a liquid crystal, and a quartz substrate for a photomask. An object of the present invention is to provide a cleaning solution for electronic materials that can be easily and economically manufactured.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, the gas dissolved in the cleaning liquid has been contacted with pure water in advance to purify the gas. It has been found that a high-purity cleaning solution for electronic materials with few impurities can be easily obtained, and the present invention has been completed based on this finding. That is, the present invention provides (1) a cleaning liquid for an electronic material, which is obtained by dissolving in a cleaning liquid a gas that has been previously cleaned by contacting with pure water. Further, as a preferred embodiment of the present invention, (2) the cleaning liquid for electronic materials according to (1), wherein the gas is a gas containing ozone, and
(3) The cleaning liquid for an electronic material according to the above item (1) or (2), which removes and cleans an inorganic component or an organic component soluble in water in a gas.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The cleaning liquid for electronic materials of the present invention is obtained by dissolving a gas, which has been previously cleaned by contacting with pure water, in the cleaning liquid. There is no particular limitation on the cleaning liquid, for example, pure water, ultrapure water, acidic cleaning liquid obtained by dissolving hydrochloric acid, sulfuric acid, hydrofluoric acid, nitric acid and the like in pure water or ultrapure water, pure water or ultrapure water. Alkaline cleaning solution in which ammonia, sodium hydroxide, etc. are dissolved, oxidizing cleaning solution in which hydrogen peroxide, oxidizing chlorine, etc. are dissolved in pure water or ultrapure water, and reducing property, in which bisulfite is dissolved in pure water or ultrapure water Washing liquids and the like can be mentioned. In the present invention, the gas dissolved in the cleaning liquid is not particularly limited, for example, ozone,
Hydrogen gas, oxygen gas, carbon dioxide gas, chlorine gas, nitrogen gas,
A rare gas such as argon can be used. The cleaning liquid for electronic material in which ozone is dissolved exhibits a very strong oxidizing power even at a low concentration of dissolved ozone, and is effective in removing organic matter contamination and metal contamination attached to the surface of the electronic material. The ozone concentration in the cleaning solution for electronic materials is 0.1 at room temperature.
Preferably it is ２０20 mg / l. The cleaning solution for electronic materials in which hydrogen gas is dissolved can remove particles adhering to the surface of the electronic material very effectively. The concentration of hydrogen gas in the cleaning liquid for electronic materials is 0.7 to 1.5 at room temperature.
It is preferably mg / liter. The cleaning solution for electronic materials in which oxygen gas is dissolved can be used for cleaning metal contamination and fine particles on the surface of electronic materials, and because oxygen gas has no self-decomposition property, it has good stability and is easy to handle. It is. The concentration of oxygen gas in the cleaning liquid for electronic materials is preferably 10 to 40 mg / liter at room temperature. The electronic material cleaning water in which carbon dioxide is dissolved can be used as rinse water after chemical cleaning. By dissolving carbon dioxide gas in ultrapure water to lower the specific resistance, charging of the electronic material surface can be prevented. The cleaning liquid for electronic materials in which chlorine gas is dissolved can be used for cleaning metal contamination on the surface of electronic materials. When used together with Megasonic, the electronic material cleaning water in which nitrogen gas is dissolved is partially ionized in nitrogen gas and the specific resistance of ultrapure water is reduced. , Can be used as rinse water. The cleaning liquid for electronic materials in which a rare gas such as argon is dissolved can be used as a cleaning liquid for the surface of the electronic material because the generation of radicals is promoted by using it together with Megasonic.

[0006] The cleaning liquid for electronic materials of the present invention is one in which a gas to be dissolved is previously brought into contact with pure water for cleaning, and then dissolved in the cleaning liquid. The pure water to be brought into contact with the gas to be dissolved is not particularly limited as long as the water quality does not transfer impurities from the pure water to the gas to be dissolved, but is usually used for preparing a cleaning liquid for dissolving the gas. The use of the same pure water is convenient from a management standpoint. For example, when the cleaning liquid is ultrapure water, the same ultrapure water is used as the pure water with which the gas is brought into contact, and when the cleaning liquid is an oxidizing cleaning liquid in which hydrogen peroxide is dissolved in ultrapure water. ,
As the pure water to be brought into contact with the gas, it is preferable to use the same ultrapure water as used in the preparation of the oxidizing cleaning liquid. Pure water to be brought into contact with the gas and pure water used for preparing the cleaning liquid are pure water having the same purity, so that there is no risk of impurities being transferred from the pure water to the gas due to the contact between the gas and the pure water, The gas can be purified. In the present invention, the method of contacting the gas to be dissolved with pure water is not particularly limited,
For example, a bubble-type gas-liquid contact method, a droplet-type gas-liquid contact method, a gas-liquid contact method using a packed tower, and the like can be given. The bubble-type gas-liquid contact method increases the contact area with pure water by converting a gas into a number of small bubbles. FIG. 1 is an explanatory diagram of one embodiment of a bubble-type gas-liquid contact device. The gas is guided to the perforated plate 3 provided at the bottom of the closed water tank 2 through the raw material gas pipe 1 and is released into pure water as a number of small bubbles. The small bubbles float in the pure water while being purified by dissolving the impurities contained in the pure water, and undergo gas-liquid separation at the upper part of the water tank container. The purified gas is transferred via the cleaning gas pipe 4 for dissolving in the cleaning liquid. It is preferable that the water tank is provided with a pure water inlet 5 and a water outlet 6 after gas cleaning, and the water in the water tank is continuously or intermittently renewed. Other examples of the bubble-type gas-liquid contact method include a plate tower such as a bubble bell tower and a perforated plate tower. In the droplet-type gas-liquid contact method, pure water is sprayed or raindrop-shaped to increase the contact area with a gas, and examples thereof include a felt-type gas cleaning device. In the gas-liquid contact method using a packed tower, pure water flows down in a thin layer along the surface of the packed bed from the top of the packed bed, and the gas rises in the gap between the packed bodies from the bottom of the tower and becomes pure. It comes into contact with water countercurrently. Among them, the bubble-type gas-liquid contact method can be suitably used because the apparatus is simple and the required power is small. Conditions for cleaning the gas by contacting it with pure water are appropriately selected in consideration of the degree of gas contamination, the pressure of the gas that can be supplied, the required gas, and the target purity of the cleaning liquid for electronic materials. be able to.

[0007] In the initial stage when gas contact with pure water is started, the gas to be dissolved in pure water for purifying the gas loses the gas to be dissolved in the cleaning liquid. But,
The pure water for cleaning is saturated with the contacting gas for a short time, and thereafter, the gas is purified without substantially losing the gas. The solubility of impurities contained in the gas to be purified in water is usually much greater than the solubility of the gas itself in water, so even after the pure water to be contacted is saturated with gas, a large amount of impurities can be removed. It can be dissolved and removed. Pure water that comes into contact with gas can be put into a gas-liquid contactor with a certain amount, and contacted with a certain amount of gas in batch mode, and then the whole amount can be renewed. It is also possible to maintain a constant water quality by changing the formula little by little. If the gas containing water-soluble impurities is dissolved in the cleaning liquid as it is, the resulting cleaning liquid for electronic materials will be of low purity containing impurities, but the cleaning liquid for electronic materials of the present invention dissolves the gas in the cleaning liquid. Before cleaning, it is contacted with pure water of the same purity as the cleaning liquid in advance, and the impurities in the gas are transferred to the aqueous phase for cleaning.Therefore, it is possible to obtain a high-purity cleaning liquid for electronic materials free of impurities. it can.

[0008]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. Example 1 A gas containing ozone produced by electrolysis of water was
After cleaning by bringing it into contact with ultrapure water using the apparatus shown in FIG. 1, it was dissolved in ultrapure water so that the dissolved ozone concentration became 5.0 mg / liter to prepare a cleaning solution for electronic materials. The concentrations of the ten metals of iron, nickel, chromium, lead, zinc, aluminum, titanium, copper, silver and platinum contained in the cleaning solution for electronic materials were measured by inductively coupled plasma emission mass spectrometry. Metal concentration is 10ng
/ Liter or less. Comparative Example 1 The same ozone-containing gas produced by electrolysis of water as in Example 1 was directly contacted with ultrapure water and purified so that the dissolved ozone concentration became 5.0 mg / liter without being purified. It was dissolved in pure water to prepare a cleaning solution for electronic materials. The concentration of the ten metals contained in this cleaning solution for electronic materials is
When measured in the same manner as in Example 1, the total metal concentration was 2
It was 5 ng / liter. Example 2 An ozone-containing gas produced by silent discharge using oxygen gas as a raw material was purified by contacting it with ultrapure water using the apparatus shown in FIG. 1, and then the dissolved ozone concentration was 5.0 mg. Per liter to prepare a cleaning solution for electronic materials. Concentration of 10 kinds of metals of iron, nickel, chromium, lead, zinc, aluminum, titanium, copper, silver and platinum contained in the cleaning liquid for electronic materials,
When measured in the same manner as in Example 1, the total metal concentration was 1
It was less than 0 ng / liter. Comparative Example 2 A gas containing ozone produced by silent discharge using the same oxygen gas as in Example 2 was brought into contact with ultrapure water and purified, and the dissolved ozone concentration became 5.0 mg / liter. Was directly dissolved in ultrapure water to prepare a cleaning solution for electronic materials. The concentrations of the ten metals contained in the cleaning solution for electronic materials were measured in the same manner as in Example 1.
Total metal concentration was 60 ng / liter. Comparative Example 3 Iron, nickel, chromium, and lead contained in ultrapure water used for cleaning and dissolving the ozone-containing gas of Examples 1 and 2 and dissolving the ozone-containing gas of Comparative Examples 1 and 2. ,zinc,
When the concentrations of 10 metals, aluminum, titanium, copper, silver and platinum, were measured in the same manner as in Example 1, the total metal concentration was 10 ng / liter or less. Examples 1-2
Table 1 shows the results of Comparative Examples 1 to 3.

[0009]

[Table 1]

From the results shown in Table 1, the gas containing ozone was purified by contacting the gas containing ozone with ultrapure water to purify it and dissolving it in ultrapure water. It can be seen that in Example 2 as well, a high-purity cleaning liquid for electronic materials having a low total metal concentration was obtained as in Example 1 using a relatively pure ozone-containing gas produced by electrolysis of water. . On the other hand, if the ozone-containing gas is directly dissolved in ultrapure water without cleaning by contacting the gas with ultrapure water, the total metal concentration in the resulting cleaning solution is high, and silent discharge Comparative Example 2 using the produced ozone-containing gas has a higher total metal concentration than Comparative Example 1 using the ozone-containing gas produced by electrolysis of water, and the purity of the used ozone-containing gas can be obtained as it is. This is reflected in the purity of the cleaning solution. Since the total metal concentration of the ultrapure water used for dissolving the ozone-containing gas measured in Comparative Example 3 was low, Comparative Examples 1 and 2 were also used.
It was confirmed that the metal component in the cleaning liquid was mixed with the ozone-containing gas used without cleaning.

[0011]

According to the cleaning liquid for electronic materials of the present invention, the gas to be dissolved in the cleaning liquid is preliminarily brought into contact with pure water to remove soluble impurities and to be purified. Can be used as a high-purity cleaning solution for electronic materials. For example, use a gas containing ozone produced by silent discharge or a gas containing ozone by electrolysis of water that has not been subjected to a special high-purification treatment as a raw material for a high-purity cleaning liquid for electronic materials. Becomes possible.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of one embodiment of a bubble-type gas-liquid contact device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Raw material gas piping 2 Sealed water tank container 3 Perforated plate 4 Purification gas piping 5 Pure water inlet 6 Water outlet after gas cleaning

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kiminobu Osawa Kurita Kogyo Co., Ltd., 3-4-7 Nishishinjuku, Shinjuku-ku, Tokyo

Claims (1)

[Claims] 1. A cleaning liquid for electronic materials, wherein a gas previously cleaned by contacting with pure water is dissolved in a cleaning liquid.