<title>Improved wafer temperature measurements</title>

Fast and accurate non-contacting temperature measurements are possible with a new approach which offers significant advantages over optical pyrometry. By using laser extensometry to measure in-plane thermal expansion, the temperature of silicon wafers can be determined during rapid thermal processing to better than 0.5 °C accuracy from room temperature to more than 1300 °C. This approach is entirely non-contacting and works on wafer surfaces exactly as they are, with no need for calibration procedures or emissivity determinations. Its 0 1 °C resolution and rapid response make it well-suited for dosed loop control of rapid thermal processing. In addition, this measurement concept lends itself well to compact packaging at low cost.