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Semiconductor treatment system and method for exchanging and treating substrate

  • US 5,564,889 A
  • Filed: 06/17/1994
  • Issued: 10/15/1996
  • Est. Priority Date: 06/18/1993
  • Status: Expired due to Term
First Claim
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1. A method of exchanging target substrates, employed in a semiconductor treatment system which has a station for mounting each substrate, and a transfer apparatus provided with a base vertically movable among upper, intermediate and lower levels, and upper and lower arms for transferring the substrates, said upper and lower arms being vertically arranged on said base and supported by said base such that they can advance and retreat independent of each other, said station being formed such that each substrate can be transferred between said station and one of said upper and lower arms by moving said one of said arms in horizontal and vertical directions,wherein said upper level of said base is set such that one of the substrates can be kept out of contact with said station when said lower arm is positioned above said station together with said one of the substrates,said intermediate level of said base is set such that said lower arm can be kept out of contact with one of the substrates when said lower arm is positioned under said one of the substrates which is placed on said station, and also such that one of the substrates can be kept out of contact with said station when said upper arm is positioned above said station together with said one of the substrates, andsaid lower level of said base is set such that said upper arm can be kept out of contact with one of the substrates when it is positioned under said one of the substrates placed on said station,said method comprising, so as to remove a first substrate, which is one of the substrates and mounted on said station, from said station by said upper arm, and to transfer a second substrate, which is one of the substrates and supported by said lower arm, from said lower arm onto said station, the steps of:

  • positioning said base at said lower level with said upper and lower arms positioned in retreat positions;

    advancing said upper arm to a position under said first substrate while said base being positioned at said lower level;

    moving said base up to said upper level after positioning said upper arm under said first substrate, thereby raising said first substrate from said station by said upper arm;

    retreating said upper arm with said first substrate and advancing said lower arm with said second substrate while said base being positioned at said upper level;

    moving said base down to said intermediate level after positioning said lower arm above said station, thereby transferring said second substrate from said lower arm onto said station;

    retreating said lower arm after transferring said second substrate onto said station; and

    confirming by an optical sensor as to whether said upper arm holds said first substrate while retreating said upper arm and advancing said lower arm, wherein said optical sensor comprises means for emitting light and means for receiving said light which are fixed relative to said base and connected to each other through an optical axis intersecting movement paths of said first and second substrates, and wherein said first substrate on said upper arm is sensed by said optical sensor when said optical axis intersects said first substrate on said upper arm and does not intersect said second substrate on said lower arm.

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