Development of 6H-SIC CMOS Transistors for Insertion into a 3500C Operational Amplifier

Silicon carbide possesses a unique combination of properties, not available from other more common semiconductors, which allow it to operate in certain severe environments. These properties include a wide bandgap, a high melting point, high breakdown electric field, and high thermal conductivity, as well as excellent resistance to chemical attack and mechanical damage. As such, it is being examined throughout the world for employment in temperature, radiation and Exp resistant electronics, high frequency/high power devices as well as blue LEDs and UV photo- detectors. Although, the excellent properties of SiC have been known since the 1950'6, its development as a semiconductor has been severly limited until recently, primarily because of difficulty in growing high quality, large area, single crystal- line material from which to fabricate devices. The development of a process for growing single crystal boules of 6H-SIC at North Carolina State University and the further improvement in process control and crystal size and quality at Cree Research, Inc. has lead to rapid advances in SiC device development and performance. Cree is in production of the world's only commercially viable blue light emitting diode (LED) using 1 inch diameter wafers produced from these boules and is in the process of scaling up to 1.375 inch production. Cree has demonstrated a complete range of field-effect transistors (MOSFETs, MESFETs, and JFETs) in SiC which can operate at temperatures in excess of 4OOuC. In many high temperature applications, analog circuits will be needed to provide an interface to high temperature sensors or actuators. These circuits will be required to provide conditioning of low level sensor signals and the transmission of signals over long cables in noisy environments. It is proposed to develop 6H-SIC CMOS transistors during Phase I for insertion into an operational amplifier which can operate continuously at 350-C in Phase II.