System for repeatable temperature measurement using surface reflectivity

摘要

A system is disclosed for externally measuring the temperature of a substrate having a reflective surface within a chamber. The system comprises a first light source having sufficient intensity for bombarding the reflective surface with photons, thereby heating the surface. The first light source has an output level and a wavelength substantially in the absorption band of silicon. The system also comprises means for exposing the substrate to a gas in order to form a layer superjacent the reflective surface. A sensor, preferably a photo detector, for sensing changes in the reflectivity of the surface is included. In one embodiment of the present invention, the sensor comprises a second light source and a sensor, for sensing the reflectivity of the surface caused by the reflecting photons. Furthermore, the system comprises control circuitry for controlling the first light source in response to the sensor; the control circuitry being coupled to the sensor by a feedback loop.