Innovative Manufacturing Process Improvements - GaN On SOD

This proposal is to demonstrate the feasibility of producing GaN-based semiconductor devices on a high thermal conductivity silicon-on-diamond (SOD) substrate where the substrate is a sandwich of silicon, diamond and silicon. Semiconductor power devices for radar applications are limited in performance and end-of-life (EOL) reliability due to high device operating temperatures. DoD electronic systems are being designed to accommodate higher power transmitters that generate larger thermal loads. The critical reliability issue is minimizing thermal energy near the transistor’s junction or channel. AlGaN/GaN HEMT structures provide higher efficiency of electrical energy in switching, but maximum performance is still limited by the thermal management problem during device operation. To improve energy transport capability of GaN technology, thermal conductivity must be maximized as close as possible to the transistor’s active region. Diamond provides the highest thermal conductivity possible and therefore diamond thin films would be the ideal substrate material for high power/high frequency semiconductor devices. It has already been demonstrated that GaN can be successfully grown on silicon substrates. The objective of this proposal is therefore to combine GaN growth on silicon with a diamond heat spreader structure built into the silicon wafer using known SOI fabrication technology.