High Dielectric MOSFET Oxides on SiC

Increasing thermal and power loads in circuitry demand electrical components which can operate at temperatures up to 400 C and beyond . A combination of high bandgap semiconductors and improved dielectrics is needed to solve this problem. ATMI has maj or programs in production of both SiC/GaN semiconductor materials and high dielectric constant complex oxide thin films, in particular barium strontium titanate (BST), which is being investigated for DRAMS. We propose to combine these capabilities, using metalorganic chemical vapor deposition (MOCVD), to produce a robust, high quality thin film of BST which could be used as a gate dielectric for SiC MOSFET devices. Because the dielectric constant of thin film BST can be as high as 600 compared to the 3.9 of SiO2, .we have seen up to l0x improvements in charge storage densities compared to standard DRAM dielectrics. Preliminary measurements also show that BST dielectrics produced by MOCVD at ATMI have excellent high temperature electrical properties, with change of capacitance less than 0.3% between O C and 200 _C. In Phase I we will develop and test BST-based dielectrics, demonstrating compatibility with test SiC devices and proving their feasibility for use at temperatures up to 300 C. Military applications for the high temperature devices proposed herein include the More Electric Plane, multi-chip modules, and a variety of high powered circuitry in radars, weapon systems, etc. Civilian needs include commercial aircraft, geophysical exploration, and harsh environments such as nuclear power stations and satellites.