Stock material or miscellaneous articles – Hollow or container type article – Polymer or resin containing
Patent
1991-02-22
1993-08-31
Lesmes, George F.
Stock material or miscellaneous articles
Hollow or container type article
Polymer or resin containing
428 1, 428 345, 428902, 428931, 206328, 361212, B65D 8542, H05F 302
Patent
active
052407535
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to molded articles for holding wafers. More particularly, the present invention relates to molded articles adapted for transporting, storing or stowing semiconductor wafers or glass plates for liquid crystal televisions free of contamination and with safety.
BACKGROUND ART
In semiconductor production processes, wafers are handled by the so-called cassette-to-cassette system wherein wafers are transported, as placed in wafer baskets or carriers, from step to step. This system has achieved remarkable increases in the quantity of semiconductors produced. The wafer production process is practiced entirely within a clean room or clean bench which is diminished in the amount of dust present to keep the surface of semiconductor wafers clean at all times.
Conventional wafer baskets are left open at opposite sides and at its upper portion for ease of cleaning, drying, transport or transfer, while wafers are generally left exposed when handled with carriers. Accordingly, wafers are very likely to be contaminated with small dust particles or the like remaining in the clean room. Wafer baskets are therefore transported or stored usually as accommodated in a closed box, whereas not infrequently, the wafer basket is transported as it is, or wafers are left exposed when transported with use of carriers, without considering the possibility of contamination. The influence of small dust particles is negligible when the width of patterns to be formed on semiconductor devices is small, but even dust particles as small as about 0.1 .mu.m produce an adverse influence as the pattern width decreases with an increase in the complexity of integration as from LSI to VLSI. Thus, it has become increasingly important to prevent dust deposition on the wafer surface.
Conventional carriers, wafer baskets for cleaning, baskets for drying, baskets for transport and storage cases are predominantly synthetic resin moldings, and most of them are electrically chargeable insulating moldings which are prepared by molding polypropylene (PP) or like resin as it is (without reinforcement). Presently, therefore carriers, baskets and storage cases are damaged by wafers, producing dust, becoming charged to attract dust and permitting promoted deposition of dust on wafers to result in a high reject ratio. Further since the resin used is not reinforced, the baskets for cleaning or drying have the drawback of having insufficient thermal rigidity. On the other hand, in the case where carriers, baskets, storage cases and like wafer holding molded articles are reinforced with glass fiber, carbon fiber, chopped fiber or the like, it is impossible to internally reinforce the moldings up to the outermost surface thereof when observed microscopically. Consequently, it is always likely that the moldings will be damaged by wafers, or wafers themselves will be damaged by moldings which are as high as 6 to 7 in Moh's hardness.
On the other hand, the resin material is subjected to an antistatic treatment usually by adding carbon black thereto, whereas carbon black is extremely fine, very low in compatibility with the resin and prone to become released and scattered about to contaminate wafers owing to abrasion or frictional contact with wafers. Although investigations were conducted on surfactants for use as antistatic agents, they fail to retain a sustained antistatic effect and become a dust attractant like insulating moldings. Moreover, even the presence of a very small amount of vapor of surfactant could lead to the serious drawback of fogging up the wafer surface.
Further in the case of liquid crystal panels, rapid progress has been made in providing precision display screens with use of glass substrates of reduced thickness, which need to fulfill the same requirements as semiconductor wafers.
We have conducted intensive research to overcome the foregoing drawbacks of the prior art and consequently found that the contamination of wafers is attributable largely to incorporation of air in the cleaning step and to c
REFERENCES:
patent: 4404615 (1983-09-01), Dep
patent: 4722441 (1988-02-01), Arai et al.
patent: 4815596 (1989-03-01), Reid
patent: 4943606 (1990-07-01), Inoue et al.
patent: 4983713 (1991-01-01), Hayashi et al.
patent: 5039525 (1991-08-01), Tamashima et al.
Nakamura Morihiko
Tabuchi Akira
Lesmes George F.
Nold Charles R.
Otsuka Kagaku Kabushiki Kaisha
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