Develop Ultra-Fast Metastable Ion Implant Activation System

Future DoD and Navy missions require advances in current high voltage power electronics technology. For this, Gallium Nitride (GaN) is a suitable materials candidate given the numerous fundamental figures of merit that make it superior to SiC and Si, respectively, the current state-of-the-art and standard material systems for power electronic devices. With the Baliga figure of merit, respectively, ~ 5× and ~850× higher than SiC and Si, GaN-based technology will enable >10kV power switching devices. However, establishing complex device geometries and doping profiles required to manufacture efficient high-voltage and high-frequency devices remained the major hurdle in the field. To overcome this, reliable ion implantation followed by post-implantation damage removal and electrical activation of dopants by annealing would be critical for the selective area doping.  Unlike SiC and Si material systems, GaN is thermodynamically unstable at high temperatures, prohibiting the use of conventional annealing methods to anneal structural damage in GaN devices. Annealing to adequately remove implant-induced damage would usually require temperatures ~2/3 of the crystal's melting point, which is ~1400-1500 °C for GaN. But GaN surface decomposes only at a temperature of ~850 °C at atmospheric pressure.  In this Phase II program, we propose to design and build a Multicycle rapid thermal annealing (MRTA) system with ultrafast sub-second heating and cooling cycle rates (>1000 K/s). The MRTA allows shorter temperature pulses and achieves a higher maximum peak temperature in GaN without decomposing the material. The short cycled multiple heating pulses provide better conditions for diffusional processes in GaN, better restore the device structure damaged by ion implantation, and improve activation of the implanted dopants while also preserving the the GaN surface integrity. The final MRTA system will be capable of delivering <2% temperature uniformity and achieving ~2500 oC steady-state heating on wafers up to 4 inches in diameter.