Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2001-07-06
2003-02-04
Dawson, Robert (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S588000, C524S544000, C524S545000, C524S546000, C525S387000, C525S375000
Reexamination Certificate
active
06515064
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a clean molded article which has an excellent plasma resistance and an excellent property of inhibiting elution of metals, has a reduced content of impurity metals and can give a sealing member to be used for sealing of a semiconductor manufacturing equipment.
BACKGROUND ART
In manufacturing semiconductor elements, very high cleanliness is required, and the requirements for high cleanliness range over not only management of a production process of semiconductors but also a semiconductor manufacturing equipment itself and parts of such equipment. Even if the parts of semiconductor manufacturing equipment are cleaned after built in the equipment, a degree of possible cleanliness is limited. Such parts are required to have been cleaned highly before built in the equipment. Contamination which becomes a problem particularly in the production of semiconductors is caused by fine particles, organic compounds and elution of metals which have an adverse effect on accurate etching treatment.
Also high cleanliness is required similarly in a molded article such as a sealing member for semiconductor manufacturing equipment which the present invention can be particularly suitably applied to. The present applicants have attained high cleanliness of the sealing member itself by employing a special method of cleaning the sealing member after molding (WO99/49997).
Such a sealing member is produced by crosslinking a crosslinkable elastomer composition such as a rubber, and in order to provide the sealing member with mechanical properties, there is a case where a carbon black is added as a filler to the composition.
In production of semiconductors, there is a case where a dry process such as plasma etching is carried out. In that dry process, there is a case where particles (impurity fine particles) are generated from molded parts produced from an elastomer. Those contaminating sources must be eliminated.
Also with respect to the sealing member used in a wet process such as cleaning process, it is desired to reduce elution of metals more.
The present invention relates to a molded article which has an excellent plasma resistance and an excellent property of metal-elution inhibition and can be obtained by crosslinking a crosslinkable elastomer composition containing a carbon black which has a reduced content of impurity metals and causes no crosslinking failure even if not only radiation crosslinking but also crosslinking with a peroxide crosslinking agent is carried out.
DISCLOSURE OF INVENTION
Namely the present invention relates to an elastomer molded article which is obtained by crosslinking a crosslinkable elastomer composition comprising a crosslinkable elastomer component and a carbon black filler having an average particle size of not more than 700 &mgr;m and an impurity metal content measured by an ashing analysis method of not more than 300 ppm. The elastomer molded article has an impurity metal content measured by an ashing analysis method of not more than 100 ppm and (1) an increasing rate of particles generated by irradiating oxygen plasma to the article is not more than 500% or (2) an amount of impurity metals extracted from the article with a 50% aqueous solution of HF is not more than 500 ppb.
In case where the molded article is used in a dry process, it is particularly preferable to use a graphitized carbon black filler. It is desirable that an average particle size of such a graphitized carbon black filler is from 10 to 100 &mgr;m, preferably from 10 to 30 &mgr;m from the viewpoint of inhibiting generation of particles after plasma irradiation.
The graphitized carbon black filler having a reduced content of impurity metals can be obtained by heat-treating a starting carbon black filler at high temperature.
When a carbon black filler containing a very small amount of impurity metals is used, the obtained molded article is particularly excellent in property of metal-elution inhibition and is used suitably for wet process. In that case, there is no problem even if an average particle size is relatively large.
According to the present invention, the crosslinkable elastomer composition obtained by adding the above-mentioned specific carbon black filler to a fluorine-containing elastomer component or a silicone elastomer component can give a sealing member having excellent mechanical and chemical properties. Further the sealing member is treated by a special cleaning process disclosed in the above-mentioned WO99/49997, namely a process for cleaning with ultrapure water, a process for cleaning with a clean organic compound in the form of liquid at a cleaning temperature or with a clean inorganic aqueous solution, a dry etching cleaning process or an extractive cleaning process, and thus a molded article for semiconductor manufacturing equipment which has a very high cleanliness and has an excellent plasma resistance and an excellent property of metal-elution inhibition can be obtained.
BEST MODE FOR CARRYING OUT THE INVENTION
The carbon black filler to be used in the present invention is a carbon black filler having an impurity metal content measured by an ashing analysis method of not more than 300 ppm and an average particle size of not more than 700 &mgr;m.
As the carbon black filler, there are a graphitized carbon black filler having a relatively small particle size and suitable for a dry process requiring plasma resistance and a carbon black filler having a low content of impurity metals (not more than 100 ppm) and suitable for a wet process requiring metal-elution inhibition property.
Among them, examples of the graphitized carbon black are, for instance, TOCABLACK #3885, #3855, #3845 and #3800 available from Tokai Carbon Kabushiki Kaisha, and the like. Particularly preferred is a carbon black having a specific surface area of not less than 3 m
2
/g and DBP oil absorption of not less than 15 ml/100 g from the viewpoint of processability.
The graphitized carbon black to be used in the present invention is one having a relatively small average particle size, preferably from 10 to 100 &mgr;m, further preferably from 10 to 30 &mgr;m. Reduction of the impurity metal content is attained by heat-treating a starting carbon black at high temperature. The average particle size means an arithmetic mean value obtained by observing carbon black fillers dispersed on a circuit board at a magnification of ×10,000 to ×200,000 with an electron microscope and measuring a particle size of 100 fillers selected at random.
Impurity metals which become a problem because the amounts thereof are particularly large are, for example, alkali metals such as Na, K and Li; alkaline earth metals such as Ca, Mg and Ba; Fe, Cu, Cr, Ni, Al, and the like.
The clean graphitized carbon black filler of the present invention is added to a crosslinkable elastomer to give a crosslinkable elastomer composition. An adding amount of the filler is from 1 to 150 parts by weight (hereinafter referred to as “part”), preferably from 1 to 60 parts on the basis of 100 parts of the elastomer component. If the filler is added more, an amount of the filler to be falling away increases, which causes generation of particles.
On the other hand, as the carbon black filler having an impurity metal content of not more than 100 ppm, there can be used a carbon black having a relatively large average particle size of as large as 500 to 700 &mgr;m, for example, a high purity MT carbon black (Ultra-Pure N-990 available from Cancarb, Co., Ltd.) or a high purity carbon black obtained by cleaning a carbon black of usual grade (for example N-990 available from Cancarb, Co., Ltd., and the like). Though it is preferable that the impurity metal content is lower, preferred more is a content of not more than 30 ppm, more preferably not more than 10 ppm.
The above-mentioned clean carbon black filler of the present invention is added to a crosslinkable elastomer to give a crosslinkable elastomer composition. An adding amount of the filler is from 1 to 150 parts, preferably from 1 t
Hasegawa Masanori
Higashino Katsuhiko
Noguchi Tsuyoshi
Tanaka Hiroyuki
Daikin Industries Ltd.
Dawson Robert
Peng Kuo-Liang
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