Apparatus and method for determining the temperature of an object in thermal processing chambers

The present invention is generally directed to a system and process for accurately determining the temperature of an object, such as a semiconductive wafer, by sensing and measuring the object radiation being emitted at a particular wavelength. In particular, a reflective device is placed adjacent to the radiating object, which causes thermal radiation being emitted by the wafer to be reflected multiple times. The reflected thermal radiation is then monitored using a light detector. Additionally, a reflectometer is contained within the system which independently measures the reflectivity of the object. The temperature of the object is then calculated using not only the thermal radiation information but also the information received from the reflectometer.