Kla Corporation

Fanuc America Corporation

Yifeng Cui

Hadi A Akeel

Anatoly Romanovsky

Zhiwei Xu

Yury Yuditsky

Mandar Paranjape

Michael A McNeill

A semiconductor wafer is inspected using a main laser beam and a secondary laser beam. The secondary laser beam leads the main laser beam and has lower power than the main laser beam. Using the secondary laser beam, a particle is detected on the semiconductor wafer having a size that satisfies a threshold. In response to detecting the particle, the power of the main laser beam and the power of the secondary laser beam are reduced. The particle passes through the main laser beam with the main laser beam at reduced power. After the particle has passed through the main laser beam with the main laser beam at the reduced power, the power of the main laser beam and the power of the secondary laser beam are restored in a controlled manner that is slower than a single step.

Large-particle monitoring with laser power control for defect inspection

The present invention recognizes that the limiting structures to size reduction for an optical encoder were the laser diode/photo diode package and the photodetector with amplifier package(s). The invention includes removing the discrete components from the laser diode cover package and mounting the much smaller discrete components on a base framework. The photodetector with amplifier package of the invention have an altered photodetector/amplifier geometry including shortening the leads between them. This resulted in significant size reduction of the encoder, a reduction in required gain and resulting increase in bandwidth. The entire base framework is temperature cooled by disposing two thermo-electric coolers between the base framework and an adjacent heat sink. Such positioning of the two coolers between the base framework and it's adjacent heat sink stabilizes both the laser diode's and the photo detector's outputs. In addition this novel design stabilizes the entire footprint/base of the encoder from thermal effects, whatever their origin.

Optical rotary position encoder

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Fremont, CA, United States of America

Yifeng Cui