| 摘要 |
An apparatus for processing a semiconductor substrate mounted in a thermal processing chamber includes a heating system for heating the substrate, which includes lamps facing a front side of the substrate and a power supply system providing power to at least one of the lamps with a DC power component and an AC power component at a selected frequency. The AC power component is a selected fraction of the DC power component. The apparatus also has a sensor facing a back side of the substrate for providing a detected signal indicative of measured radiation from the back side of the substrate. A lock-in system provides a lock-in signal indicative of a magnitude of an AC component of the detected signal at the selected frequency in response to the detected signal and a reference signal at the selected frequency. A processing system is adapted to determine a transmitted portion of the measured radiation that is transmitted through the substrate based upon the lock-in signal, the detected signal and the selected fraction.
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