Wafer Temperature Measurement and Control During Laser Spike Annealing

Sub-melt millisecond annealing technologies have been widely accepted for current and future IC fabrication. Real-time temperature control, both within wafer and from wafer-to-wafer, is one of the key challenges that must be addressed for the successful introduction of any millisecond annealing technology into a production environment. In this paper, we show results from a novel pyrometry approach that measures the peak wafer temperature during Laser Spike Annealing (LSA) processes. The melting point of silicon has been utilized for the temperature calibration of the pyrometer. The accuracy of the measured temperature has been assessed with melting of other materials such as Si_xGei_1-x. This unique temperature measurement system has been integrated into the LSA temperature control system, where the measured wafer temperature is used to modulate laser output power to achieve uniform temperatures both within the wafer and from wafer to wafer. Uniformity and repeatability on blanket Rs monitor wafers and patterned device wafers are presented demonstrating the performance of the temperature measurement and control system in a production environment.