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Fast Slow Level Control for Focal Plane Registration Disclosure Number: IPCOM000051757D
Original Publication Date: 1981-Mar-01
Included in the Prior Art Database: 2005-Feb-10

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Related People

Admirand, DJ Kneule, W Kraus, GK [+details]


A control system permits wafers to be leveled in the focal plane of a projection printing apparatus within 0.5 micron. By providing a slow driver control when the wafer approaches a level condition, the response of the non-contact focal registration (NCFR) is made compatible with the response of the pressure differential switch.