JP4081728B2 - Ozone-containing ultrapure water supply device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gas-containing ultrapure water supply device. More specifically, the present invention provides a use point of ultrapure water containing a specific gas that is useful for cleaning and rinsing in a wet cleaning process for precisely cleaning electronic materials such as silicon substrates for semiconductors and glass substrates for liquid crystals. The present invention relates to a gas-containing ultrapure water supply device that can be effectively supplied to a gas.
[0002]
[Prior art]
Highly removing impurities such as fine particles, metals, and organic substances from the surface of electronic materials is extremely important to ensure the quality and yield of products such as semiconductors and liquid crystals. Conventionally, silicon substrates for semiconductors, glass substrates for liquid crystals, etc. are called RCA cleaning, a mixture of sulfuric acid and hydrogen peroxide, a mixture of hydrochloric acid, hydrogen peroxide and water, ammonia and hydrogen peroxide. It was cleaned by high-temperature cleaning using a concentrated chemical solution based on hydrogen peroxide, such as a mixture of water. When this cleaning method is adopted, the chemical cost, the ultrapure water cost for rinsing, the waste liquid treatment cost, the air conditioning cost for exhausting chemical vapor and creating new clean air are reduced, and the use of a large amount of water, In recent years, the wet cleaning process has been reviewed in order to reduce environmental burdens such as mass disposal and emission of exhaust gas.
For example, Japanese Patent Laid-Open No. 7-14817 discloses a cleaning that enables a reduction in the amount of chemicals used, a reduction in cleaning time, a reduction in the number of chemicals used, a recovery of waste liquids, and a reduction in capital investment in cleaning silicon wafers. As a method and apparatus, a chemical cleaning process for continuously supplying a chemical flow from above the surface of the object to be cleaned while rotating the object to be cleaned horizontally and supplying ultrapure water as a method and apparatus. A method and an apparatus have been proposed in which the ultrapure water cleaning process is sequentially performed in the same cleaning tank and ozone-added ultrapure water is used as the first chemical solution.
In addition, the present inventors previously disclosed in Japanese Patent Application Laid-Open No. 8-316187 that metal contaminants and organic contaminants on a semiconductor substrate can be efficiently removed without using chemicals such as high-concentration hydrochloric acid or hydrogen peroxide. A cleaning method using cleaning water prepared by blowing ozone into an acidic aqueous solution containing a chlorine compound was proposed as a cleaning method that enables removal and facilitates waste liquid treatment after cleaning. Further, the present inventors have also disclosed a hydrogen gas-containing ultrapure water obtained by dissolving hydrogen gas in ultrapure water and an oxygen gas-containing ultrapure water containing dissolved oxygen gas at a concentration higher than the atmospheric saturation concentration. It has been found to be effective for cleaning, and has proposed a new resource-saving cleaning method using these gas-containing ultrapure water.
The present inventors provide a gas-containing ultrapure water production apparatus for dissolving these specific gases in ultrapure water, and a gas-containing ultrapure water supply for supplying gas-containing ultrapure water for cleaning to a point of use. Several effective proposals have also been made for devices. However, gas-containing ultrapure water for cleaning has a short history since its development, and further improvement of the gas-containing ultrapure water supply device has been demanded in order to realize mass-use without waste in mass production factories. .
[0003]
[Problems to be solved by the invention]
The present invention continuously produces gas-containing ultrapure water for cleaning in which the dissolved concentration of a specific gas is controlled, and can be stably and quickly supplied even for intermittent use at a point of use. It is made for the purpose of providing a containing ultrapure water supply device.
[0004]
[Means for Solving the Problems]
As a result of intensive research to solve the above problems, the present inventors have obtained a buffer tank that stores ozone- containing ultrapure water in a branch pipe that branches from the ozone- containing ultrapure water main pipe and is connected to a use point. It has been found that the capability of the supply device is greatly improved, and that stable and rapid supply to the use point of ozone- containing ultrapure water becomes possible, and the present invention is completed based on this knowledge. It came to.
That is, the present invention
(1) and the ozone-containing ultra pure water supply main pipe for transferring ultra-pure water containing ozone, the branch pipe connecting to the point of use branched from the main pipe, the ozone-containing ultrapure water to the branches pipes one for each the plurality have a buffer tank for storing, supplying water to the excess of the ozone-containing ultrapure water which has not been used by ultraviolet irradiation to decompose the ozone in the use point to the branch pipe as dilution water for use in point of use An ozone-containing ultrapure water supply device characterized by adjusting the dissolved ozone concentration of the ozone- containing ultrapure water,
(2) The ozone- containing ultrapure water supply device according to item (1), wherein the capacity of each buffer tank is substantially equal to the amount of water used at one time at a use point;
(3) The ozone- containing ultrapure water supply device according to (1) or (2), which cleans the electronic material at a use point ; and
(4) The ozone- containing ultrapure water supply device according to ( 1 ) , ( 2 ) or (3) , wherein gas-liquid separation is performed in a buffer tank ;
Is to provide.
Furthermore, as a preferred embodiment of the present invention,
(5) The ozone- containing ultrapure water supply device according to item (1) for cleaning the electronic material at a use point;
Can be mentioned.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
The gas-containing ultrapure water supply device of the present invention includes a gas-containing ultrapure water supply main pipe for transferring gas-containing ultrapure water, a branch pipe branched from the main pipe and connected to a use point, and a branch pipe And a buffer tank for storing the gas-containing ultrapure water. According to the apparatus of the present invention, ultrapure water containing a gas useful for cleaning and rinsing is effective as a use point in a wet cleaning process for precisely cleaning electronic materials such as a silicon substrate for a semiconductor and a glass substrate for a liquid crystal. Can be supplied to. By using the apparatus of the present invention, impurities such as fine particles, metals, and organic substances can be highly removed from the surface of the electronic material.
There are no particular restrictions on the gas contained in the gas-containing ultrapure water supplied using the apparatus of the present invention, for example, noble gases such as ozone, hydrogen gas, oxygen gas, carbon dioxide gas, chlorine gas, nitrogen gas, argon, etc. Can be mentioned. Ultrapure water containing ozone can be used for cleaning organic material contamination and metal contamination on the surface of electronic materials. The ozone concentration in the ozone-containing ultrapure water is preferably 0.1 to 20 mg / liter at room temperature. Ultrapure water containing hydrogen gas can be used to remove fine particles adhering to the surface of the electronic material. The hydrogen gas concentration in the hydrogen gas-containing ultrapure water is preferably 0.7 to 1.5 mg / liter at room temperature. The oxygen gas-containing ultrapure water can be used for cleaning metal contamination on the surface of the electronic material. The oxygen gas concentration in the oxygen gas-containing ultrapure water is preferably 10 to 40 mg / liter at room temperature.
Carbon dioxide-containing ultrapure water can be used as rinse water after chemical cleaning. By dissolving carbon dioxide gas in ultrapure water and reducing the specific resistance, charging of the surface of the electronic material can be prevented. The chlorine gas-containing ultrapure water can be used for cleaning metal contamination on the surface of the electronic material. When combined with Megasonic, nitrogen gas-containing ultrapure water ionizes part of the nitrogen gas and lowers the specific resistance of ultrapure water, so it can be used as rinse water, just like carbon dioxide-containing ultrapure water. it can. Ultrapure water containing a rare gas such as argon can be used as cleaning water for the surface of an electronic material because generation of radicals is accelerated by applying megasonic.
[0006]
FIG. 1 is a system diagram of one embodiment of the gas-containing ultrapure water supply device of the present invention. The ultrapure water sent to the apparatus is branched into an ultrapure water supply system 1 and a gas-containing ultrapure water supply system 2. The gas to be dissolved is supplied from the gas supplier 3 to the ultrapure water of the gas-containing ultrapure water supply system, and is supplied to the ultrapure water in the gas mixing unit 4. There is no particular limitation on the gas supply device, for example, a gas required in the apparatus can be generated, such as an ozone generator, or a gas container obtained separately such as a hydrogen gas container can be connected to gas. It can also be a feeder. There is no particular limitation on the gas mixing part, for example, by blowing gas directly into ultrapure water and transferring it in the gas-containing ultrapure water supply main pipe in a gas-liquid mixed state, the gas can be dissolved in ultrapure water. Alternatively, the gas can be dissolved in ultrapure water using a gas permeable membrane module or the like.
The apparatus of the present invention includes a gas-containing ultrapure water supply main pipe 5 for transferring gas-containing ultrapure water, a branch pipe 6 branched from the main pipe and connected to a use point, and a gas containing pipe disposed in the branch pipe It has a buffer tank 7 for storing ultrapure water. The gas-containing ultrapure water in the buffer tank is sent to the cleaning tank 8 and used for cleaning electronic materials. In this embodiment, the branch pipe 9 is also provided in the ultrapure water supply system 1, and the gas concentration in the gas-containing ultrapure water can be adjusted by adding the ultrapure water to the gas-containing ultrapure water. Ultrapure water that has not been used at the point of use can be returned through the return pipe of the ultrapure water supply system and used again. Gas-containing ultrapure water that has not been used at the point of use can be recycled as it is, or it can be reused as ultrapure water or as primary pure water by removing the contained gas as necessary. it can. There is no restriction | limiting in particular in the removal method of contained gas, For example, ozone containing ultra pure water can remove ozone by activated carbon treatment, ultraviolet irradiation, etc.
[0007]
FIG. 2 is a system diagram showing the vicinity of the buffer tank according to one aspect of the apparatus of the present invention. The gas-containing ultrapure water is continuously produced and sent through the gas-containing ultrapure water supply main pipe to the vicinity of a cleaning machine such as a batch type or a single wafer type which is a use point. The gas-containing ultrapure water is stored in the buffer tank 7 through the branch pipe 6 branched from the main pipe.
In the apparatus of the present invention, the buffer tank has a function as a standby container for intermittent supply of gas-containing ultrapure water to the use point. In mass production plants, gas-containing ultrapure water as cleaning water is used intermittently. In the case of batch cleaning, a supply process for quickly filling an empty cleaning tank with cleaning water and a standby process until the next supply process are repeated. During the standby process, there may be an overflow or down-flow circulation type cleaning in which a certain amount of makeup water is continuously sent to the cleaning tank. Also in the case of single wafer cleaning, the supply process of applying a liquid at a constant flow rate to the object to be cleaned is repeated intermittently. In any case, intermittent supply is required in the place of cleaning, but in order to control the dissolved gas concentration without waste, it is preferable to continuously produce gas-containing ultrapure water. There was a problem. In the apparatus of the present invention, the requirement for both continuous production and intermittent use of gas-containing ultrapure water can be met by storing gas-containing ultrapure water in the buffer tank. The buffer tank is preferably provided with a supply / exhaust valve 10 and a sterile filter 11 so as to cope with fluctuations in the amount of water.
In the apparatus of the present invention, the capacity of the buffer tank is preferably substantially equal to the capacity of the washing tank at the use point or the amount of water used at one time at the use point. For example, in the case of batch cleaning, if the capacity of the cleaning tank is 20 liters, the capacity of the buffer tank is also set to 20 liters, so that the cleaning water can be updated easily and quickly. That is, by disposing the buffer tank 7 above the cleaning tank 8, a predetermined amount of cleaning water can be filled into the cleaning tank using gravity only by a simple valve operation. The water supply speed to the cleaning tank can be increased by opening the supply / exhaust valve. The buffer tank is preferably provided with a water meter, and a mechanism for sending a signal to the controller to automatically open and close the valve to replenish the gas-containing ultrapure water.
[0008]
In the buffer tank, the dissolved gas concentration can be finely adjusted. The branch pipe 6 is provided with a gas sensor 12 for measuring the concentration of the gas contained in the ultrapure water, a signal is sent from the gas sensor to the controller 13, and the gas-containing ultrapure water supply main pipe is supplied by the controller from the main pipe. By controlling the opening of the pure water valve 14 and the opening of the ultra pure water valve 15 supplied from the ultra pure water supply system 1, the gas-containing ultra pure water and the ultra pure water to be replenished to the buffer tank are controlled. By adjusting the amount of water, the gas concentration of the ultrapure water containing gas in the buffer tank can always be kept constant.
The gas-containing ultrapure water is sent to the washing tank, and the empty buffer tank is supplied again with the gas-containing ultrapure water at a constant flow rate from the main pipe that is fed at a constant flow rate. In the apparatus of the present invention, it is preferable to provide a plurality of buffer tanks for one branch pipe. By providing two or more buffer tanks for one point of use, one buffer tank is used for standby and the other buffer tank is used for replenishment, depending on the interval between cleaning water updates at the point of use, that is, the average flow rate used By performing the replenishment, it is possible to make steady the extraction of gas-containing ultrapure water from the main pipe to the branch pipe. Although the amount of water flow in the main pipe decreases as the water flows to the branch pipes as it goes downstream, the water flow amount of the main pipe can also be made steady by performing the steady state of the water supply amount to the branch pipes.
By stabilizing the amount of water flow in the main pipe and the branch pipe, the concentration management of gas-containing ultrapure water that causes a decrease in concentration over time due to self-decomposition of ozone or the like is facilitated. That is, the dilution at each use point can be performed constantly, and the concentration management of the self-decomposable gas in each buffer tank is facilitated. When the use condition of the washing water at the point of use fluctuates, gas concentration management is performed by monitoring the dissolved gas concentration in the branch pipe or buffer tank using a gas sensor and controller, and a dilution mechanism by operating the valve accordingly. It is also possible to use it. Strictly speaking, when handling ultrapure water containing a self-decomposable gas such as ozone, the dissolved gas concentration in the buffer tank also decreases due to self-decomposition. However, the progress of the concentration decrease is much more gradual than in the gas-containing ultrapure water supply main pipe, and there is no concentration decrease that causes a practical problem unless it is in an extremely long time standby.
[0009]
In the apparatus of the present invention, a pH adjuster can be added in the buffer tank to adjust the pH of the gas-containing ultrapure water in the buffer tank to a predetermined value. For example, you can measure the pH of gas-containing ultrapure water in the buffer tank and send a signal to the controller to add the required amount of pH adjuster, or the inflow of gas-containing ultrapure water to the buffer tank Alternatively, a necessary amount of a pH adjusting agent can be added according to the amount of water sent to the use point.
In the apparatus of the present invention, gas-liquid separation can be performed in a buffer tank. When the gas contained is a gas that does not cause a substantial change in concentration in the closed supply system, such as hydrogen gas, oxygen gas, carbon dioxide gas, nitrogen gas, or rare gas, the gas is mixed in the gas mixing unit 4. Using the permeable membrane module, it is possible to produce gas-containing ultrapure water in which no bubbles are present in the ultrapure water. However, in the case of containing a self-decomposing gas such as ozone, a gas containing ozone is blown into ultrapure water so as to be in a gas-liquid mixed state, and ozone that decreases due to self-decomposition in ultrapure water is reduced. It is preferable to replenish with ozone dissolved in the ultrapure water from the gas phase and keep the dissolved ozone concentration substantially constant over a long supply main piping system. In this case, ozone undissolved in ultrapure water and other gases coexisting with ozone are sent to the buffer tank in a gaseous state. Therefore, by performing gas-liquid separation in the buffer tank, gas-containing ultrapure water is obtained. Air bubbles can be separated from The gas generated by the gas-liquid separation can be discharged from a supply / exhaust valve provided in the buffer tank.
In order to keep the concentration of self-decomposing gas such as ozone constant over a long supply main piping system, a gas-liquid mixed gas-containing ultrapure water supplier that passes water while dissolving the self-decomposing gas It is effective to use piping. However, even if this method is used, it is difficult to maintain a constant gas concentration from upstream to downstream of a long supply system. For this reason, gas-containing ultrapure water set to a higher concentration is sent so that the prescribed dissolved gas concentration can be maintained even at the most downstream use point where the self-decomposition of dissolved gas is most advanced. The method of adjusting the dilution to an appropriate concentration is a practical method. In addition, a self-decomposable gas can be appropriately supplied in the middle of the gas-containing ultrapure water supply main pipe. In this case, the lowest concentration is not necessarily the lowest in the downstream, but even when gas is replenished in the middle of the main pipe, the gas concentration is set higher than the required concentration at the point of use and around each point of use. It is preferable to make fine adjustment with.
[0010]
FIG. 3 is a system diagram of another aspect of the apparatus of the present invention for supplying ozone-containing ultrapure water. The ultrapure water sent to the apparatus is supplied with a gas containing ozone from the ozone supplier 16 and supplied to the ultrapure water in the ozone mixing unit 17. It is preferable that the ozone-containing gas is blown directly into the ultrapure water and transferred through the ozone-containing ultrapure water supply main pipe in a gas-liquid mixed state. By transferring the ozone-containing supply main pipe in a gas-liquid mixed state, the ozone in the ultrapure water lost due to self-decomposition is supplemented by the ozone dissolved in the ultrapure water from the gas phase, and the ozone concentration in the ultrapure water Can be kept almost constant.
The apparatus of this aspect includes an ozone-containing ultrapure water supply main pipe 18 for transferring ultrapure water containing ozone, a branch pipe 19 branched from the main pipe and connected to a use point, and ozone disposed in the branch pipe. It has the buffer tank 20 which stores the containing ultrapure water. The ozone-containing ultrapure water in the buffer tank is sent to the cleaning tank 21 and used for cleaning electronic materials. In this embodiment, the ozone-containing ultrapure water that has not been used at the point of use is sent to the ozone decomposing device 22 where ozone is decomposed and removed, and then returned via the return pipe 23. There is no restriction | limiting in particular in the mechanism of an ozonolysis apparatus, For example, ozone can be decomposed | disassembled by ultraviolet irradiation, activated carbon treatment, etc. In the apparatus of this aspect, the branch pipe 24 is also provided in the return pipe, and the ozone concentration in the ozone-containing ultrapure water is diluted by adding and diluting the ultrapure water from which ozone is decomposed and removed to the ozone-containing ultrapure water. Can be adjusted. Ultrapure water from which ozone that has not been used has been decomposed and removed can be used again as ultrapure water or as primary pure water. When the pH of ozone-containing ultrapure water used at each use point is the same, pH adjustment by adding a pH adjuster can be performed collectively in the main piping system upstream or downstream of the ozone mixing section. it can.
[0011]
【The invention's effect】
The gas-containing ultrapure water supply device according to the present invention can connect continuous production and intermittent use of cleaning water by providing a buffer tank near the point of use, and can stably supply gas-containing ultrapure water. Gas-containing ultrapure water whose gas concentration is controlled can be intermittently and rapidly sent to a cleaning tank, a cleaning nozzle or the like while being manufactured and continuously supplied. In addition, since the gas-liquid separation mechanism can be performed in the buffer tank, it is not necessary to install a dedicated device for gas-liquid separation even when performing gas-liquid mixed type water flow.
[Brief description of the drawings]
FIG. 1 is a system diagram of one embodiment of a gas-containing ultrapure water supply device of the present invention.
FIG. 2 is a system diagram showing the vicinity of a buffer tank according to an aspect of the apparatus of the present invention.
FIG. 3 is a system diagram of one embodiment of the device of the present invention for ozone-containing ultrapure water.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Ultrapure water supply system 2 Gas containing ultrapure water supply system 3 Gas supply 4 Gas mixing part 5 Gas containing ultrapure water supply main pipe 6 Branch pipe 7 Buffer tank 8 Washing tank 9 Branch pipe 10 Supply / exhaust valve 11 Aseptic filter 12 Gas Sensor 13 Controller 14 Valve 15 Valve 16 Ozone Supply 17 Ozone Mixer 18 Ozone-Containing Ultrapure Water Supply Main Pipe 19 Branch Pipe 20 Buffer Tank 21 Washing Tank 22 Ozone Decomposition Device 23 Return Pipe 24 Branch Pipe

Claims (4)

Storing the ozone-containing ultra pure water supply main pipe for transferring ultra-pure water containing ozone, the branch pipe connecting to the point of use branched from the main pipe, the ozone-containing ultrapure water to the branches pipes one for each the buffer tank plurality Yes, supplying water to the excess of the ozone-containing ultrapure water which has not been used by ultraviolet irradiation to decompose the ozone in the use point to the branch pipe as dilution water, ozone-containing used in point of use An ozone- containing ultrapure water supply device that adjusts the dissolved ozone concentration of ultrapure water. 2. The ozone- containing ultrapure water supply device according to claim 1, wherein the capacity of each buffer tank is substantially equal to the amount of water used at one time at a use point. The ozone- containing ultrapure water supply device according to claim 1 or 2 , wherein the electronic material is washed at a use point . 4. The ozone- containing ultrapure water supply device according to claim 1 , wherein gas-liquid separation is performed in a buffer tank .

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