Aplex, Inc.

Mike Chao

Tim H Huynh

Huey M Tzeng

Chi Guo

An automated tracking and control system measures the lateral displacement of a moving belt, using non-contact sensing. The displacement signal is provided to an algorithm that adjusts the tilts of the belt pulleys and steers the belt laterally. Non-contact sensors include inductive proximity sensors, which respond to the metal belt but are immune to airborne slurry and other non-metallic debris in a hostile environment typical of wafer polishing. Other non-contact sensors include shielded optical sensors. Dual sensor configurations cancel response to non-lateral displacements. Instrumentation, such as tension sensors, cylinder pressure sensors, load transducers, and limit switches, provides input to the algorithm. Independent tension signals for each belt edge verify proper functioning of, e.g., pad conditioners. User-specified belt displacements, e.g., dither, sawtooth oscillation, step, ramp, and sweep, combine with selective texturing and other variable pad properties to provide a desired polishing rate profile.

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San Jose, CA, United States of America

Mike Chao