Innovators at NASA's Glenn Research Center have developed ultra-thin silicon carbide (SiC) microstructures that enable highly sensitive pressure sensors that are biocompatible. The novel method of fabricating these microstructures, Dopant Selective Reactive Ion Etching (DSRIE), allows for structures as thin as 2 microns to be achieved, while allowing multifunctional sensors to be fabricated on a single SiC wafer. For the first time, it is possible to batch-fabricate ultra-thin SiC diaphragms that can sense very low pressures, enabling pressure sensors that can measure sub-psi pressures. This faster process makes it easier and less costly to produce complex, advanced semiconductors that are fully functional at temperatures greater than 600 °C. This technique enables a new generation of SiC-based microelectromechanical systems (MEMS) and nanoelectromechanical systems (NEMS) such as accelerometers, pressure sensors, and biosensors.
Glenn's invention produces ultra-thin SiC-based microstructures and diaphragms that are essential for high-sensitivity pressure sensors that not only monitor engines but can also act as biosensors (monitoring bone density or brain pressure). DSRIE offers selective etching that reliably isolates conductive microstructures from the bulk material and has precision-etch control that minimizes yield loss due to manufacturing defects. Therefore, the thickness of structures, such as diaphragms, can be ultra-thin and selectively realized during dopant reactive ion etching.
Until now, batch fabrication of SiC sensors has been hindered by the fact that only one type of sensor per wafer could be produced at a time. Given the expense of fabrication, this limitation has greatly reduced the commercial viability of SiC sensors and electronics. Glenn's batch fabrication offers manufacturers the opportunity to simultaneously produce multiple multifunctional MEMS/NEMS products on a single SiC wafer. Such products include flow sensors, pressure sensors, biosensors, accelerometers, inertial sensors, angular rate sensors, and yaw rate sensors.