Karta Technologies, Inc.

Karta Technology, Inc.

Jorge J Alcoz

Charles E Duffer

A system for controlling process temperatures for semi-conductor wafers comprises a heater to heat the wafer, an element to generate a plurality of ultrasonic vibrations in the wafer, a Sagnac interferometer adapted to sense the ultrasonic vibrations and generate a wafer temperature signal responsive thereto, a system to calculate the wafer temperature on the basis of the generated wafer temperature signal, and a control element the wafer heater on the basis of the calculated wafer temperature. A method for controlling process temperatures for semi-conductor wafers comprises the steps of heating the wafer, generating a plurality of ultrasonic vibrations in the wafer, sensing the ultrasonic vibrations with a Sagnac interferometer, generating the wafer temperature signal in response to sensing the ultrasonic vibrations with the Sagnac interferometer, calculating the wafer temperature on the basis of the generated wafer temperature signal, and controlling the heat applied to the wafer on the basis of the calculated wafer temperature.

System and method for controlling process temperatures for a semi-conductor wafer

A method and apparatus for detection of ultrasonic vibrations using an interferometer built, in its preferred embodiment, with optical fibers is disclosed. The method and apparatus are particularly useful where perturbations and disturbances adversely affecting other interferometer configurations are encountered. Light from a laser is split into two orthogonal polarization modes which travel through different fiber-optic paths and are directed to the object being investigated. A waveplate and a polarization splitter are used to re-direct the reflected light into the optical path opposite from which it arrived. A second polarization splitter combines the returning light and an interference signal is obtained with photodetectors. The bias phase-shift between the interfering beams is fixed with a second waveplate. The detected signal is the result of motion which modulates the phase of the light reflected by the object being inspected.

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San Antonio, TX, United States of America

Jorge J Alcoz