Micro-adjustable wafer retaining apparatus

Abstract

An easily adjustable wafer retaining ring for both coarse and micro-adjustable engagement with a carrier head assembly of a chemical-mechanical polishing apparatus is disclosed. The carrier head supports the wafer on a wafer support surface during the polishing process. The wafer is held in place by a wafer retaining ring which has an inner and an outer set of threads around the inner and outer circumferences of the retaining ring. The carrier head has engagement means for engaging the retaining ring using the inner and outer threads of the retaining ring. The lower surface of the retaining ring has a groove, preferably, v-shaped which is in contact with the carrier head and parallel to the plane of rotational engagement of the retaining ring with the carrier head. A locking ring is receivably engageable with the groove of the retaining ring. A lock limits further vertical displacement of the retaining ring by bearing pressure down on the locking ring. The carrier head is attached to a fixed ring by retaining ring bolts. The bolts provide for a coarse adjustment of the vertical displacement of the retaining ring by threadably engaging the retaining ring with the carrier head to a predetermined depth relative to the wafer support surface. The bolts provide for a fine adjustment of the vertical displacement of the retaining ring, by using the lock to provide pressure to engage the locking ring with the retaining ring in order to limit further vertical displacement of said retaining ring.