Methods for controlling retaining ring and wafer head tilt for chemical mechanical polishing

Abstract

A CMP system and methods make repeatable measurements of eccentric forces applied to carriers for wafer or polishing pad conditioning pucks. Force applied to the carrier may be accurately measured even though such force is eccentrically applied to such carrier. The CMP system and method provide the repeatable measurement features while supplying fluids within the carrier to the wafer and to a wafer support without interfering with the polishing operations. Similarly, the CMP system and methods remove fluids from the wafer or puck carrier without interfering with the CMP operations. An initial coaxial relationship between an axis of rotation and a carrier axis is maintained during application of the eccentric force, such that a sensor is enabled to make repeatable measurements, as defined above, of the eccentric forces, and the carrier may be a wafer or a puck carrier. Such initial coaxial relationship is maintained by a linear bearing assembly mounted between the carrier and the sensor, and the carrier may be a wafer or a puck carrier. The linear bearing assembly is provided as an array of separate linear bearing assemblies, wherein each separate linear bearing assembly is dimensioned independently of the diameter, for example, of a wafer or puck carried by the carrier. The linear bearing assembly may be assembled with a retainer ring in conjunction with a motor for moving the ring relative to the wafer mounted on the carrier so that an exposed surface of the wafer and a surface of the retainer ring to be engaged by the polishing pad are coplanar during the polishing operation.