Abstract: A carrier head that holds an object such as a wafer for a polishing system can be rotated during polishing. One such carrier head includes a sensor that determines the relative orientation of (or the angle between) a movable chuck and a fixed drive structure. A control system uses these measurements to select the edge pressure applied to the wafer or the chuck to control the attack angle of the wafer against polishing pads. By actively adjusting the attack angle, a carrier head can accommodate torques about an axis not in the plane of contact between the wafer and the polishing pad even when the wafer is otherwise free to rotate about the axis. One carrier head includes a drive plate with projections ending with balls that are disposed in matching openings in a carrier plate. Radial elongation of openings and curvature of the balls permit rotation of the carrier plate about an axis in plane passing between the carrier and drive plates.

Abstract: A polishing system such as a chemical mechanical belt polisher includes a hydrostatic fluid bearing that supports polishing pads and incorporates one or more of the following novel aspects. One aspect uses compliant surfaces surrounding fluid inlets in an array of inlets to extend areas of elevated support pressure around the inlets. Another aspect modulates or reverses fluid flow in the bearing to reduce deviations in the time averaged support pressure and to induce vibrations in the polishing pads to improve polishing performance. Another aspect provides a hydrostatic bearing with a cavity having a lateral extent greater than that of an object being polished. The depth and bottom contour of cavity can be adjusted to provide nearly uniform support pressure across an area that is surrounded by a retaining ring support. Changing fluid pressure to the retaining ring support adjusts the fluid film thickness of the bearing.

Abstract: A polishing tool uses a seal cavity containing a fluid that supports polishing pads against an object being polished. In one embodiment, the boundaries of the cavity include a support structure, a portion of a polishing material, and a seal between the support structure and the polishing material. The polishing material moves relative to the support structure and seal. A variety of seal configuration can maintain the fluid within the cavity. One seal includes an o-ring that the force of a spring, a magnet, or air pressure presses against the polishing material. A gas flow from outside the cavity or from an inlet inside the cavity can form a gas pocket in the cavity, adjacent the o-ring, to prevent leakage of the fluid past the o-ring. Another seal is formed by an aerostatic bearing. The fluid pressure in the cavity can be varied temporally to create vibrations in the polishing material to enhance polishing performance or can be varied spatially to change the pressure profile.

Abstract: An in-situ sensor measures polishing pads during chemical mechanical polishing. From the measurements, polishing pads can be identified as worn out or unevenly worn and replaced. Scheduling maintenance according to current measurements, rather than according to statistical predictions, minimizes down time for maintenance and still prevents use of worn out or unevenly worn polishing pads. Alternatively, a tool is reconfigured according to the polishing pad measurements. Reconfiguring the tool can prolong pad life and improve polishing performance. One embodiment of the invention includes a non-contact sensor such as a laser sensor that directs an incident beam at a target area and determines a distance to a reflection point by triangulation of incident and reflected beams. As polishing pads wear, distances to the reflection points increase. Movement of the polishing pads and the sensor during polishing causes the in-situ sensor to measure portions of the polishing pads that are along a zigzag trajectory.