Advances in silicon carbides and their MEMS pressure sensors for high temperature and pressure applications

High-temperature pressure sensors have recently attracted considerable interest for potential applications in the automotive, aerospace, and deep-well drilling industries, where they are required for monitoring gas or liquid pressures under extremely high temperatures and/or high pressures in harsh corrosive environments. Silicon carbide (SiC) is a third-generation semiconductor material with a wide band gap and excellent high-temperature stability and is regarded as a good candidate for overcoming the high-temperature intolerance of traditional pressure sensors. Currently, there are few reviews on recent advances in the synthesis, characterization, sensing mechanisms, design methodology, fabrication processes, operation, and application issues of SiC-based pressure sensors used under extreme application conditions. This review explores the following key topics: (i) key properties and special attributes of SiC materials; (ii) synthesis of SiC materials and thin films for high-temperature pressure sensor applications and processing of SiC materials, including etching, ohmic contacts, and bonding; (iii) recent development of SiC piezoresistive pressure sensors, including those based on silicon-on-insulator and all-SiC designs; (iv) recently reported SiC capacitive pressure sensors, including both 3C-SiC-based and all-SiC designs; and (v) advances in SiC-based fiber-optic pressure sensors. Finally, we highlight the key challenges and future prospects of next-generation SiC-based high-temperature pressure sensors.