a method for calibrating at least one temperature sensor . a wafer having calibration structures of a material having a melting point in the range of 150 ° to 1150 ° c . is provided . the temperature sensor is operable to detect a temperature dependent characteristic of the wafer and output a signal corresponding to the temperature depending characteristic . the power input is selectively varied and the wafer temperature is ramped for a calibration run . a wafer characteristic , such as wafer reflectance , radiance , or emissivity , is monitored . a first step change in the wafer characteristic corresponding to a wafer temperature equal to the melting point of the calibration structures is detected and a set of calibration parameters for each temperature sensor being calibrated is calculated .