Polishing tool having a sealed fluid chamber for support of polishing pad

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. One embodiment of the invention includes one or more fluid inlet/outlets to the cavity, one or more pressure regulators, and a controller that operates the pressure regulators to control the pressure in the cavity. In polishers with or without a sealed fluid cavity, the support structure can include actuators that control the orientation of the support structure relative to polishing material. Sensors and a feedback control system positions the support structure for polishing.