JP2003142449A - Washing apparatus and method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a washing apparatus that can reutilize ozone water that has been once used for washing, can perform efficient washing work without stopping the apparatus even during the setting of a new substrate or the like, and is used for washing the substrate and peeling a resist. SOLUTION: In the washing apparatus, the washing of a substrate or the peeling of a resist is carried out by ozone water circulation in the apparatus. The washing apparatus has a storage tank of ozone water in an ozone water circulation line. By the washing method, the washing of the substrate or the peeling of the resist is carried out by the washing apparatus.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention makes it possible to reuse ozone water once used for cleaning, and it is not necessary to stop the apparatus during the setting of a new substrate, etc. The present invention relates to a cleaning device that can be used for cleaning a substrate or stripping a resist.

[0002]

2. Description of the Related Art The step of cleaning a substrate such as a semiconductor or a liquid crystal is an essential step for removing foreign substances such as organic substances and metals adhering to the surface of the substrate during the manufacturing process. Conventionally, an RCA cleaning method using sulfuric acid, ammonia, hydrochloric acid or the like has been used for cleaning a substrate such as a semiconductor. In the commonly used RCA cleaning method, different chemicals are used for cleaning the organic substance and for cleaning the metal. For cleaning the organic substance, a mixture of sulfuric acid and hydrogen peroxide is used. A chemical solution is used, and a mixed chemical solution of hydrochloric acid and hydrogen peroxide has been used for cleaning the metal. Since such cleaning is performed using a new chemical solution for every ten and several batches, a large amount of chemical solution is required. For this reason, when the RCA cleaning method is used, the cost of the chemical solution is high, and a large amount of waste liquid is generated, and there is a great disadvantage in terms of both cost and environment when treating the waste liquid.

Further, when forming a circuit on a semiconductor substrate or forming a plurality of colored pixels having different hues in a pattern on a liquid crystal substrate, a photolithography process is an essential process. For example, in the case of forming a circuit on a semiconductor substrate, a resist is applied on the wafer, an image consisting of a resist pattern is formed by a normal photo process, the resist is used as a mask, and the unnecessary resist is removed. In order to remove and form a circuit, and to form a next circuit, a resist is applied again, and a cycle of image formation-etching-resist removal is repeated.

In the resist stripping process for removing the resist that is no longer needed, conventionally, in the resist stripping of the semiconductor substrate,
The RCA cleaning method using an asher (ashing means) or sulfuric acid, hydrogen peroxide or the like is used, and a mixed solution of an organic solvent and an amine or the like has been used for stripping the resist from the liquid crystal substrate. However, using an asher to remove the resist may damage the semiconductor due to the high temperature,
In addition, it was not possible to remove inorganic impurities.
Also, when removing the resist using a solvent or chemical,
As stripping is performed using a new chemical solution for each dozen or more batches, a large amount of chemical solution is required and the chemical solution cost is increased, and a large amount of waste solution is generated, which is both cost and environmental aspects when treating the waste solution. There was a big disadvantage.

On the other hand, ozone water obtained by dissolving ozone gas in water exerts excellent effects on sterilization, deodorization, bleaching, etc. due to the strong oxidizing power of ozone, and ozone gas is harmless oxygen (gas) over time. Since it self-decomposes and has no persistence, it is attracting attention as an environmentally friendly sterilizer, cleaning agent, bleaching agent, etc., and ozone water is being considered for cleaning substrates and stripping resist.

As a method of producing ozone water, there is a method of dissolving ozone in water using a gas dissolving membrane, and Japanese Patent Laid-Open No. 7-23880 discloses an apparatus using a porous hollow tubular ozone gas permeable membrane. Is disclosed. However, since the porous ozone gas permeable film is apt to be clogged, it was not possible to circulate the ozone water once used for cleaning the substrate or stripping the resist for reuse. Also, in a porous ozone gas permeable membrane, the ozone gas diffuses into the water through the water that has penetrated into the pores, so the ozone gas pressure is adjusted to be slightly weaker than the water pressure in order to penetrate the water into the pores. The ozone gas pressure cannot be made higher than the water pressure, so it is not possible to prepare high-concentration ozone water, and low-concentration ozone water has a small ozone dissolution amount, making efficient cleaning difficult. Met.

Further, if the porous gas dissolving film is clogged, the amount of dissolved ozone is reduced, the life of the module is shortened, and the cleaning rate and the ozone utilization efficiency are reduced. Further, in a cleaning device using a porous ozone gas permeable film, there is a problem that bubbles are likely to be mixed in ozone water at the start and end of the operation of the device, and if the bubbles adhere to the substrate, cleaning efficiency is reduced. It was

[0008]

In view of the above situation, the present invention makes it possible to reuse ozone water once used for cleaning, and it is also necessary to stop the apparatus while setting a new substrate or the like. It is an object of the present invention to provide a cleaning device used for cleaning a substrate or stripping a resist, which enables efficient cleaning work.

[0009]

SUMMARY OF THE INVENTION The present invention is a cleaning apparatus for cleaning a substrate or removing a resist with ozone water circulating in the apparatus, the cleaning apparatus having an ozone water storage tank in an ozone water circulation line. is there. The present invention is described in detail below.

The cleaning apparatus of the present invention will be described with reference to the drawings showing one embodiment thereof. The cleaning apparatus shown in FIG. 1 includes an ozone generator 1, an ozone gas detector 2, an ozone dissolution module 3, an ozone water detector 4, a reaction tank 5, a storage tank 6, and a pump 7.

In the ozone generator 1, ozone gas for dissolving in water is generated. The ozone generator 1 is not particularly limited, and a known ozone generator can be used. The ozone gas concentration generated by the ozone generator 1 is measured and monitored by the ozone gas detector 2. The value of the ozone gas concentration measured by the ozone gas detector 2 is fed back to the ozone generator 1, and the concentration of the ozone gas generated by the ozone generator 1 is adjusted at any time.

The ozone gas generated by the ozone generator 1 is
It is dissolved in water in the ozone dissolution module 3. As the ozone dissolving module 3, for example, one having a structure in which the gas dissolving film 8 is housed inside the ozone dissolving module 3 as shown in FIG. 2 can be used.
In the embodiment shown in FIG. 2, the gas dissolving film 8 is made of a non-porous hollow fiber. When the gas dissolving film 8 is non-porous, the ozone molecules 9 permeate between the molecular chains of the resin forming the gas dissolving film 8 and then diffuse into water.

The gas dissolving film is preferably non-porous. In a porous gas-dissolved film, ozone gas is first dissolved in water that has penetrated into the pores of the gas-dissolved film, and then ozone diffuses into the water according to a concentration gradient. When it is circulated, the pores are clogged with foreign matter and ozone gas cannot be dissolved in water. On the other hand, if a non-porous gas-dissolving film is used, the gas-dissolving film will not be clogged, so the ozone water once used for cleaning can be reused by circulating it again in the equipment. can do. Also, in a porous gas-dissolving film, ozone gas dissolves in water through the water that has penetrated into the pores.Therefore, the ozone gas pressure must be strictly adjusted to be lower than the water pressure in order to permeate the water into the pores. Therefore, the ozone concentration of ozone water cannot be increased. On the other hand, when a non-porous film is used as the gas dissolving film, the ozone gas pressure does not need to be lower than the water pressure, and the ozone gas pressure can be increased to obtain high-concentration ozone water. Further, in the porous gas-dissolving film, there is a risk that bubbles that reduce the cleaning efficiency are mixed into ozone water through the pores, but when a non-porous gas-dissolving film having no pores is used, bubbles may be mixed. Absent.

The non-porous gas dissolving film is preferably formed by molding a silicone resin or a fluorine resin. A non-porous gas-soluble film made of a silicone-based resin or a fluorine-based resin has excellent corrosion resistance and deterioration resistance, and has a property of efficiently transmitting ozone gas.

Examples of the fluorine-based resin include tetrafluoroethylene-based resin polymers such as polytetrafluoroethylene copolymer (PTFE), perfluoroalkoxy resin (PFA), fluorinated ethylene-propylene resin (FEP); Fluorine-based rubber and the like can be mentioned, and examples of the above-mentioned silicone-based resin include polydimethyl siloxane and methyl silicone rubber. Any resin can be used as a raw material for the non-porous film as long as it is a perfluorinated resin.

It is preferable that the silicone-based resin or the fluorine-based resin is formed into a hollow fiber (tube shape) having a required inner diameter and length. By using a hollow fiber,
Ozone can be dissolved more efficiently than when it is used as a flat film. After bundling a plurality of the obtained hollow fibers, both ends are heat-sealed or adhered to each other and housed in the outer shell of the ozone dissolving module 3.

The outer cover of the ozone dissolving module 3 is not particularly limited as long as it has excellent ozone resistance and airtightness, and is made of, for example, PFA, PTFE, vinylidene fluoride resin, stainless steel material or the like. There is something like.

When the non-porous gas-soluble membrane is made of hollow fibers, the water for dissolving ozone gas may flow either inside (inside the tube) or outside the hollow fibers. And ozone gas passes through the inside. When water flows inside the hollow fiber, the hollow fiber may be clogged with foreign matter.

The dissolved ozone gas concentration of ozone water generated in the ozone dissolution module 3 is monitored and controlled by the ozone water detector 4. The saturated dissolution concentration of ozone in water at normal pressure and room temperature is 50 to 60 ppm, but the dissolved ozone gas concentration of ozone water used for cleaning the substrate is
It is preferably higher from the viewpoint of cleaning effect. Therefore, the cleaning apparatus of the present invention preferably has a means for pressurizing ozone gas and a means for pressurizing the inside of the reaction tank. By pressurizing the ozone gas or the inside of the reaction tank, the concentration of dissolved ozone gas in ozone water can be increased to about 200 ppm. As a means for pressurizing the ozone gas and the reaction tank,
The ozone gas generated by the ozone generator 1 and the inside of the reaction tank are not particularly limited as long as they can be pressurized to a pressure higher than normal pressure, but a pressure pump using an ozone resistant gas material is preferably used.

The obtained ozone water is used in the reaction tank 5 for cleaning the substrate and stripping the resist. The substrate is not particularly limited, and examples thereof include a semiconductor substrate such as a silicon wafer and a liquid crystal substrate such as a glass plate. The resist is not particularly limited and may be either a negative type or a positive type. The cleaning method in the reaction tank 5 is not particularly limited, and examples thereof include batch processing (dip) and single-wafer processing (spraying). Of these, batch processing is preferable. The dissolved ozone gas concentration of ozone water used to clean substrates is 20p.
Since it is about pm, cleaning was performed by single-wafer processing. However, in the present invention, the ozone gas concentration of ozone water can be increased to about 200 ppm by pressurizing ozone gas or the inside of the reaction tank. A large number of substrates can be processed at once by the processing.

The reaction tank 5 may have means for irradiating it with ultraviolet rays. By irradiating with ultraviolet rays, the decomposition rate of ozone is accelerated, and the cleaning effect can be enhanced accordingly. Therefore, a higher cleaning effect can be obtained by using the high-concentration ozone water in combination with the ultraviolet irradiation. The means for irradiating the ultraviolet rays is not particularly limited, and examples thereof include a UV lamp and the like. The wavelength of the ultraviolet rays to be irradiated is preferably around 254 nm, which is absorbed by ozone.

In the present invention, the ozone water may be blended with an additive for enhancing the cleaning effect. The additive is not particularly limited, and examples thereof include acidic compounds such as sulfuric acid, hydrochloric acid, nitric acid and hydrofluoric acid; organic solvents such as acetic acid, acetone and acetonitrile; alkyl sulfonates, polyoxyethylene alkyl ethers, polyoxyethylene sorbitan. Examples include surfactants such as alkylate, polyoxyethylene alkylphenyl ether, and perfluoroalkyl sulfonate. When cleaning the substrate, it is preferable to add an acidic compound or an organic solvent. It is preferable to add a surfactant or an organic solvent. Furthermore, it was also clarified that the solubility of ozone gas in water increases when an organic solvent is added.

The cleaning apparatus of the present invention has a storage tank for temporarily storing ozone water. If the cleaning device is stopped while a new substrate or the like is set in the reaction tank 5 and the cleaning device is restarted after the setting of the substrate is completed, it takes time to start the cleaning device. It cannot be done efficiently. On the other hand, if a bypass is provided in the middle of the circulation line in front of the reaction tank 5 and the ozone water that has flowed through the bypass is temporarily retained in the storage tank 6, the bypass will be used while setting a new substrate or the like. By switching the flow path of the ozone water so that the ozone water flows, it is not necessary to stop the cleaning device even during the setting of the substrate or the like, and the cleaning work can be efficiently performed.

Further, the storage tank 6 preferably has a function of draining a part of ozone water by overflow.
Foreign substances such as organic substances, metals, and resists are mixed in the ozone water used for the repeated cleaning, which may cause a decrease in cleaning efficiency. Also, when ozone is dissolved in water under pressure, when the obtained ozone water is placed under normal pressure,
Bubbles may be generated in ozone water. At this time,
When the storage tank 6 has a function of draining a part of the ozone water by overflow, as shown in FIG. 5, the ozone water once used for cleaning was mixed with the ozone water by flowing into the storage tank 6. Foreign matter can be removed, and even if bubbles are generated in ozone water, they can be removed. In the embodiment shown in FIG. 1, a single storage tank 6 is provided behind the reaction tank 5, but a plurality of storage tanks 6 may be provided,
Further, it may be provided in front of the reaction tank 5.

The cleaning device of the present invention has a structure in which ozone water circulates in the device. The ozone water used for cleaning the substrate in the reaction tank 5 is returned to the ozone dissolving module 3 by the water pump 7, and the consumed ozone gas is supplied. The ozone water supplemented with ozone gas can be used again for cleaning the substrate in the reaction tank 5. As a result of the study by the present inventors, it was also clarified that the cleaning efficiency is improved by circulating the ozone water in the apparatus. The mechanism of this phenomenon is unknown, but when ozone self-decomposes, it exerts a strong oxidizing action, which causes a cleaning action, but with the circulation of ozone water, the radicals generated from the substance to be decomposed also circulate, This is considered to contribute to the reaction.

The cleaning apparatus of the present invention may further have a water supply line for supplementing the ozone water reduced by repeated circulation. Water supplied to the cleaning apparatus of the present invention is not particularly limited, but ultrapure water is preferably used because it is used for cleaning the substrate and stripping the resist.

Since the cleaning apparatus of the present invention having such a structure has the storage tank, the ozone water once used for cleaning can be reused, and further, it can be used for setting a new substrate or the like. Also, it is not necessary to stop the device, and efficient cleaning work can be performed. A cleaning method of cleaning the substrate or removing the resist using the cleaning apparatus of the present invention is also one aspect of the present invention.

[0028]

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

(Example) An apparatus shown in FIG. 3 was produced. In the device, an inner diameter of 0.5 mm, a thickness of 0.04 mm, and a length of 100, which are made of polytetrafluoroethylene resin
An ozone gas detector 2 (manufactured by Riko Kagaku Co., Ltd .: OZR) is placed in an ozone dissolution module 3 that accommodates 1000 cm hollow fibers.
-3000) and an ozone gas generator 1 (manufactured by Mitsubishi Electric Corporation: ozone generation unit OP-35N-
S) is connected to the ozone gas generator 1 and the oxygen flow rate is 2 L /
Min., A raw material gas was sent at a nitrogen flow rate of 40 mL / min, ozone gas was generated at a generated current of 1.55 A, and the generated ozone gas was pressurized to an ozone gas pressure of 0.25 MPa and supplied to the ozone dissolution module 3 to generate ozone water. . Dissolved ozone gas concentration of generated ozone water is ozone water detector 4
It was measured with (Riko Kagaku Co., Ltd .: OZR-3000). The generated ozone water is circulated in the route B and directly circulated in the waste tank 10 without being circulated in the apparatus, or is circulated in the route A and pumped 7 (Takumina Co .: CS-52-FTC-).
HW) is used to circulate the inside of the apparatus and to flow only the ozone water overflowing from the storage tank 6 into the waste tank 10. The water pressure inside the device is 0.2 MPa, and the gas pressure is 0.2 MPa.
And The water temperature was 21 ° C. The dissolved ozone gas concentrations in the ozone water in the waste tank 10 were compared between when the B route was circulated and when the A route was circulated, and the results are shown in Table 1.

[0030]

[Table 1]

From the results shown in Table 1, it was found that the ozone concentration of ozone water was higher when the ozone water produced by the ozone dissolution module was circulated in the apparatus through route A. Further, when ozone water was circulated in the apparatus, the dissolved ozone gas concentration did not decrease even if the flow rate of ozone water increased. Therefore, it can be seen that the cleaning effect is higher when the substrate is cleaned by circulating ozone water.

[0032]

EFFECTS OF THE INVENTION Since the present invention is constructed as described above, ozone water once used for cleaning can be reused, and there is no need to stop the apparatus during the setting of new substrates. It is possible to provide a cleaning device that can be used for cleaning a substrate or stripping a resist, which can perform an efficient cleaning operation.

[Brief description of drawings]

FIG. 1 is a schematic view showing one embodiment of a cleaning apparatus of the present invention.

FIG. 2 is a schematic diagram showing an ozone dissolution module.

FIG. 3 is a schematic diagram showing an apparatus used in Examples.

[Explanation of symbols]

1 Ozone generator 2 Ozone gas detector 3 Ozone dissolution module 4 Ozone water detector 5 reaction tanks 6 storage tanks 7 pumps 8 Gas dissolution membrane 9 Ozone molecule 10 waste tank

Claims (5)

[Claims] 1. A cleaning device for cleaning a substrate or stripping a resist with ozone water circulating in the device, wherein the ozone water circulation line has a storage tank for ozone water. 2. The cleaning apparatus according to claim 1, wherein the storage tank has a function of draining a part of ozone water by overflow. 3. The cleaning apparatus according to claim 1, wherein ozone water is generated by dissolving ozone in water through a non-porous gas dissolving film. 4. The substrate cleaning apparatus according to claim 3, wherein the non-porous gas dissolving film is made of a hollow fiber formed by molding a silicone resin or a fluorine resin. 5. A cleaning method comprising cleaning the substrate or removing the resist by using the cleaning device according to claim 1.