Spike annealing of silicon wafers using millimeter-wave power

The millimeter-wave heating has a potential to be an alternative RTP technique for the processing of large-size wafers. Results of experiments performed on a gyrotron system at a frequency of 30 GHz have demonstrated feasibility of the spike annealing of the 3" wafers. The ramp-up rate of 110°C/s and cooling rate of 165°C/s have been achieved in the cold-wall cavity of the system at an input power of 4.5 kW Experimental results are used to derive the effective emissivity and microwave absorptivity of Si wafers. The model for microwave heating of wafers in an untuned supermultimode cavity is developed. The ray tracing analysis is used in the model to simulate the microwave intensity distribution in the cavity. The model is used to calculate the power needed to spike anneal 200 mm and 300 mm diameter Si wafers. The temperature non-uniformity over the wafers is estimated, and the method for the control over the temperature distribution is discussed.