This Small Business Innovation Research Phase I project proposes an innovative material system based on cubic SiC membranes formed on micro-machined silicon-on-insulator (SOI) substrates for advanced high temperature piezoresistive sensor applications. The SiC-on-insulator (SiCOI) structure couples high temperature benefits of SiC active layers with micro-machining and CMOS processing advantages of a silicon substrate. A material with these properties could immensely benefit automotive and aerospace industries by offering a superior alternative to conventional Si to fabricate sensors that can operate at harsh temperature (up to 500 C) environment, such as a combustion engine. Recently, Spire has developed an epitaxial technique to grow high quality cubic SiC layers on SOI substrates by initially carbonizing the top Si layer of the structure to form a SiC seed layer for subsequent CVD growth of SiC epitaxial material to form SiCOI wafers. In Phase I, Spire will develop micro-machining techniques for creating SiC membranes from SiCOI structures and use them to conduct a feasibility study on demonstrating high temperature piezoresistive sensors. Phase II will optimize process parameters for fabrication of SiCOI membranes aimed at developing commercially viable devices. Phase II will also establish a foundation for commercialization of the technology upon its development. SiCOI materials are generally ideal for a wide range of high temperature electronic and optoelectronic applications such as power devices and W photodiodes. Piezoresistive sensors based on SiCOI structures, in particular, have many applications in the automotive and aerospace industries. These sensors may be used as pressure, strain, force, or acceleration monitoring devices in harsh conditions without cooling requirements, thus resulting in significant reduction in cost, weight, and volume of the system.
