Flash Thermal Processing Through the Melting Point of Silicon

摘要

The recent capability to achieve sub-millisecond surface temperature increases of greater than 600°C over the entire surface of 300 mm wafers using flash-assist rapid thermal processing, fRTP has allowed the exploration of silicon's response to rapid thermal processes over the entire surface of the wafer. Previous results from high-speed processing of silicon through its equilibrium melting point have only been attainable by localized, small area, application of high-powered lasers. We report data obtained from a narrow band radiometer, operating at 1450 ±30 nm with a 25 kHz sampling rate, that indicates anomalous emissions during melting. Interesting re-crystallization behavior of the bare silicon surface that is cooling 500,000°C/s through its equilibrium melting point after a flash anneal from an intermediate temperature of 900° C is also reported. Wafer survivability after exposure to greater than 600°C surface temperature jumps from intermediate temperatures of 700°C to 900°C also demonstrates the inherent robustness of the wafer to withstand large thermal gradient at elevated bulk temperatures imposed during fRTP.