Photocopying – Projection printing and copying cameras – Methods
Patent
1981-05-01
1982-10-12
Moon, Charlie T.
Photocopying
Projection printing and copying cameras
Methods
29559, 29569R, 51235, 269 21, 430396, G03B 2900, B25B 1100, B23Q 700
Patent
active
RE0310530
ABSTRACT:
An apparatus and method for holding a thin workpiece such as a semiconductor wafer for operations which require the workpiece to have a high degree of planarity such as photolithographic printing includes positioning the workpiece onto a planar holding face comprising the points of a multiplicity of regularly spaced-apart substantially parallel pins with a thin rim encompassing all pins to contain a vacuum in the region adjacent to the workpiece. The small abutting area of each pinpoint abutment reduces the probability of dirt particles collecting on the holding face and provides a high thrust pressure to dislodge dirt particles interposed between the abutment and the workpiece. A small amount of lateral motion is imparted to the workpiece when it first contacts the holding face to brush off any dirt particles on the abutments.
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Firtion Victor A.
Herriott Donald R.
Poulsen Martin E.
Rongved Leif
Saunders Thomas E.
Bell Telephone Laboratories Incorporated
Canepa Lucian C.
Moon Charlie T.
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