Ultratech Stepper, Inc.

James B Owens, Jr

Yun Yu Wang

Andrew M Hawryluk

Somit Talwar

The closed loop embodiment includes a pulsed laser controller to selectively operate a pulsed laser in a lower-power probe mode or a higher power operational mode. In lower-power probe mode, values of e (total radiation energy flooding ICs on a silicon wafer), e (fraction of e specularly reflected), e (fraction of e scattered) and e (fraction of e transmitted through wafer) are obtained. A value for e (fraction of e absorbed wafer) is calculated i.e. e &equals;e &minus;(e &plus;e &plus;e ), and e used by pulsed laser controller with pulsed laser in higher power operational mode to adjust pulsed laser fluence over the duration of a pulse to provide flooding radiation energy sufficient to melt an amorphized silicon surface layer beneath radiation-absorbent material, yet insufficient to melt crystalline silicon or ablate radiation-absorbent material. Open loop embodiment substitutes a separate low-power probe laser for operation in lower-power probe mode.

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San Jose, CA, United States of America

James B Owens, Jr