Gas separation: processes – Selective diffusion of gases – Selective diffusion of gases through substantially solid...
Reexamination Certificate
2001-10-02
2003-11-18
Spitzer, Robert H. (Department: 1724)
Gas separation: processes
Selective diffusion of gases
Selective diffusion of gases through substantially solid...
C096S006000, C096S008000, C096S010000, C096S014000
Reexamination Certificate
active
06648945
ABSTRACT:
This application is the National phase of International Application PCT/JP00/02151, filed Apr. 3, 2000, which designated the U.S. and that International Application was not published under PCT Article 21(2) in English.
TECHNICAL FIELD
The present invention relates to a hollow fiber membrane module having superior chemical resistance used for deaeration treatment of chemicals in a semiconductor production process, printers, liquid crystal sealing process or chemical production process and so forth, its potting material and a chemical deaeration method using said hollow fiber membrane module.
This application is based on Japanese Patent Application No. Hei 11-97064 and Japanese Patent Application No. Hei 11-132580), the contents of which are incorporated herein by reference.
BACKGROUND ART
In a semiconductor production process, a photoresist liquid is coated onto a thin film laminated onto a semiconductor wafer, and after exposing and developing through a mask in which a pattern is formed, is etched to form a pattern in the thin film.
At this time, in the developing step, a developing solution (chemical) is typically pumped to a discharge nozzle with nitrogen gas and discharged from that nozzle to spin coat developing solution onto the semiconductor wafer. However, the pressure applied to the chemical when discharged from the nozzle may return to atmospheric pressure resulting in the supersaturated dissolved gas forming bubbles. If the developing solution is spin coated onto the semiconductor wafer while still containing bubbles, development is incomplete resulting in the occurrence of undeveloped portions. Thus, it is necessary to deaerate the nitrogen gas that is dissolved in the chemical pumping step to inhibit the formation of bubbles.
Moreover, in a semiconductor production process, in a step in which an interlayer insulating film is coated followed by cutting away the non-flat portion around the film (edge rinsing step), work is performed in which a solvent (consisting primarily of alcohol) is dropped onto the film to dissolve the peripheral edge of the film. In addition, in an edge rinsing step performed in the same manner as in the case of the above interlayer insulating film after having coated a thin film having a low dielectric constant, work is performed in which a solvent (such as alcohol, ether, ketone or hydrocarbon) is dropped onto the film to dissolve the peripheral edge of the film. In these steps, the solvent that is used is also pumped with nitrogen gas. Consequently, bubbles may form when the pressure is released thereby resulting in the formation of bubbles along with the splashing of liquid droplets onto the film causing the occurrence of defects. Thus, in order to eliminate these defects, it is necessary to deaerate the gas dissolved in the solvent to inhibit the formation of bubbles.
Moreover, in addition to the developing solution and solvent mentioned above, it is also necessary to deaerate a photoresist solution as necessary.
In addition, deaeration is also performed for printer ink as well. In an ink jet printer equipped with a piezo element head, pressurization and depressurization are repeated several times by the piezo element during ink discharge. At this time, dissolved nitrogen, oxygen and other gases in the ink filled in the head grow into bubbles and these bubbles easily accumulate in the head. Consequently, these bubbles are discharged during ink discharge causing the occurrence of printing omissions.
In addition, in an ink jet printer equipped with a thermal head, gas dissolved in the ink grows into bubbles during head driving in the thermal cycle of rapid heating and cooling of the ink, and these bubbles easily accumulate in the head. Consequently, these bubbles are discharged during ink discharge causing the occurrence of printing omissions.
Thus, it is necessary to reduce the concentration of dissolved gas in the ink and inhibit the formation of bubbles by deaerating in these printers as well.
As an example of a technology relating to deaeration of dissolved gas in a chemical using a membrane, a deaerating membrane module for semiconductor developing solution is proposed in Japanese Unexamined Patent Application, First Publication No. Hei 9-187629. The deaerating membrane module disclosed here is that in which those portions of the housing and/or end caps, hollow fiber membrane and end seals that come in contact with chemical are composed of a material having superior developing solution resistance.
With respect to this deaerating membrane module, epoxy resin is used as a preferable example of the material of its sealing material (potting material). Examples of epoxy resins include glycidyl ether, glycidyl ester, glycidyl amine, aliphatic epoxide and alicyclic epoxide, while examples of curing agents include aliphatic polyamines, alicyclic polyamines, polyamide amines and polyamides.
In addition, a preferable example of a hollow fiber membrane is a heterogeneous hollow fiber membrane composed of poly-4-methylpentene-1, and having a pore-free, homogeneous thin film layer that is continuous with the surface of a porous membrane.
In addition, a method in which dissolved nitrogen in a chemical is deaerated using a non-porous (homogeneous) tube membrane, in which poly(tetrafluoroethylene) resin having superior solvent resistance is formed into the shape of a tube, is proposed in Japanese Unexamined Patent Application, First Publication No. Hei 8-243306 and Japanese Unexamined Patent Application, First Publication No. Hei 9-7936.
In addition, as an example of printer ink deaeration technology, an ink deaeration method for ink jet recording is proposed in Japanese Unexamined Patent Application, First Publication No. Hei 5-17712. This is a method for deaerating ink using a gas permeable membrane having a thickness of 10 &mgr;m or less composed of polyethylene resin, polypropylene resin, poly(tetrafluoroethylene) resin, polystyrene resin, polymethyl methacrylate resin and so forth.
However, in the deaerating membrane module described in the above Japanese Unexamined Patent Application, First Publication No. Hei 9-187629, the chemical resistance of each member used in the deaerating module was evaluated according to the amount of change induced by chemical immersion for 3 months. Consequently, this method for evaluating chemical resistance was unable to accommodate members in which deterioration progresses rapidly after 3 months of immersion. Deaerating membrane modules using such members had problems with long-term stability. In addition, although each of the members of this deaerating membrane module exhibit a certain degree of resistance to alkaline chemicals like semiconductor developing solution, they were not resistant to chemicals such as alcohols, photoresist, printer ink and liquid crystal, and had problems such as swelling and elution caused by these chemicals. Consequently, this deaerating membrane module was unable to be used for deaerating chemicals such as alcohols, photoresist, printer ink and liquid crystal, etc.
In order to solve this problem, a membrane module was proposed in which the entire module is composed of thermoplastic resin having high resistance to solvents and other chemicals as proposed in Japanese Examined Patent Application, Second Publication No. Hei 7-34850, Japanese Examined Patent Application, Second Publication No. Hei 7-34851 and Japanese Unexamined Patent Application, First Publication No. Hei 1-293105. In the production of these modules, in order to separate the one side and the other of the membrane in a fluid-tight or airtight manner, a thermoplastic resin is used for the potting material when fixing the membrane to the housing, and particularly when fixing the hollow fiber membrane to the housing with the potting material. Consequently, it is essential to melt the potting material for potting processing.
However, in the case of performing potting processing by melting the potting material, it is necessary to select a hollow fiber membrane that it is able to withstand the heat during processing, thereby
Kato Osami
Niikawa Kenji
Takeda Satoshi
Tasaka Hiroshi
Uenishi Masamoto
Fitch Even Tabin & Flannery
Mitsubishi Rayon Co. Ltd.
Spitzer Robert H.
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