SiC Power MOSFET with Improved Gate Dielectric

High power, SiC, metal-oxide semiconductor field effect transmitters (MOSFETs) are needed for a variety of applications, including nuclear physics research. However, SiC MOSFET device technology has been hampered by several device limitations, such as a low electron mobility, an unstable threshold voltage, poor gate oxide reliability, and the lack of a reliable gate dielectric. This project will develop a high performance, next generation SiC MOSFET based on the Atomic Layer Deposition (ALD) of high-dielectric constant (high-k) gate dielectrics. The use of ALD-deposited high-k gate oxides will reduce the thermal budget by eliminating the need for a high temperature thermal oxide growth step, resulting in a cheaper device. The high-k gate dielectrics will reduce the leakage current through the gate oxide, resulting in improved device performance. Finally, the ALD process will lead to a higher quality SiC/high-k interface, resulting in improved gate oxide reliability, improved electron mobilities, and a more stable threshold voltage. Phase I will first employ ALD to deposit thin aluminum oxide, aluminum silicate, hafnium oxide, and hafnium silicate on prototype SiC MOSFETs. The fabricated MOSFETs will be characterized for leakage current, threshold voltage, dielectric reliability, and electron mobility, in order to demonstrate improved MOSFET performance in comparison to a standard silicon dioxide gate dielectric. The results of Phase I will determine which gate dielectric is the most promising for further development in Phase II. Commercial Applications and Other Benefits as described by the Applicant: The improved SiC MOSFETs should be applicable to logging, drilling, industrial processes, aerospace systems, lighting, consumer electronics, industrial electronics, and the automotive industry. SiC devices also should find use in industrial motors and power supplies requiring high voltage. In addition to performance benefits, SiC offers significant cost saving opportunities by eliminating the need for expensive cooling systems.