Silicon Wafer Temperature Measurement 

We have demonstrated a supercontinuum laser module for accurate temperature measurement of silicon wafer under processing. An optical power measurement device along with a csalibration and measuremnt modules give temperature of wafer accurate to ~10C. It utilizes the following principle. Silicon has strong temperature dependence of absorption of NIR wavelengths. This property has been utilized to build a compact packaged source for active non contact temperature measurement of silicon wafer under processing.

Contact temperature measurements using thermocouples are problematic as they can contaminate the sample and suffer from unreliable contact. Non-contact measurements like Pyrometry, which rely on radiation processes, are also unreliable as the emissivity of silicon wafers varies significantly with temperature, doping, surface smoothness, and oxide deposition. These variations in emissivity affect the accuracy of temperature measurements and limit the minimum temperature that can be measured using pyrometric techniques.