Auto-centering device for mechanical clamp

摘要

A substrate holding mechanism which is particularly adaptable to automatically centering a semiconductor wafer on a platen spider as the wafer is lowered from a wafer loading and unloading position to a wafer processing position in a medium current implanter such as a Varian EHP500. Upon subsequent placement of a mechanical clamp on the wafer to hold the wafer on the platen, the clamp fingers of the clamp engage the edge of the wafer with substantially uniform pressure to prevent micro-cracking or fracturing of the wafer.