Patent ID: 6935466

Claim:
A semiconductor processing system, comprising: a vacuum chamber having an interior adapted to maintain an internal chamber pressure below ambient atmospheric pressure; a pump coupled to said chamber and adapted to reduce said internal chamber pressure to a pressure below ambient atmospheric pressure; a workpiece support adapted to support a workpiece having an underside; an alignment member disposed above said workpiece support and having an alignment surface; a plurality of lift pins, each lift pin having an engagement surface adapted to engage said alignment surface, and each lift pin also having piston means, responsive to the difference between said internal chamber pressure and said ambient atmospheric pressure, for elevating each lift pin from a first position to a second extended position in which each lift pin engagement surface engages said alignment surface; wherein the height of each lift pin within said chamber is a function of the difference between said internal chamber pressure and said ambient atmospheric pressure so that each lift pin is elevated from said first positions to said second extended positions as said pump reduces said internal chamber pressure.