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Pneumatic Switch Adjustable Gap Assembly

IP.com Disclosure Number: IPCOM000087093D
Original Publication Date: 1976-Dec-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Fick, J: AUTHOR

Abstract

A semiconductor wafer leveling and height-sensing system includes a sensing head positioned over the wafer which blows nitrogen onto the wafer surface through three sensing nozzles (IBM Technical Disclosure Bulletin, Vol. 16, No. 10, March 1975, page 3255). The sensing nozzles work in conjunction with differential pressure switches. Flow control valves are used to balance the sense head pressure within the differential pressure switch.

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Pneumatic Switch Adjustable Gap Assembly

A semiconductor wafer leveling and height-sensing system includes a sensing head positioned over the wafer which blows nitrogen onto the wafer surface through three sensing nozzles (IBM Technical Disclosure Bulletin, Vol. 16, No. 10, March 1975, page 3255). The sensing nozzles work in conjunction with differential pressure switches. Flow control valves are used to balance the sense head pressure within the differential pressure switch.

For stability and fine-pressure adjustment, two variable flow control valves 1 and 2 are provided in series. Valve 1 is for coarse adjustment and valve 2 is for fine adjustment. The valves are used with a differential pressure switch (not shown) and serve as a pressure reference on one side of the switch.

Coarse adjustment valve 1 is set with a screwdriver and may creep or move slightly to a "comfortable" position. Once it is in this position, it does not change. The fine adjustment valve 2 is adjusted with micrometer head 3. The micrometer screw, fine-threaded with negligible backlash, further controls the flow from the coarse restriction.

The micrometer head assembly can be eliminated and a fine-pitched lead screw can be substituted. The lead screw would require a flat face on one end and a knob on the other end. Also aluminum block 4 would require threading.

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