Integration of Microelectromechanical Systems (MEMS) with Electronics in Silicon Carbide for harsh environment

The proposed research focusses on issues associated with the development of integrated SiC MEMS and has the following aims:

1. To extend optimised SiC MEMS processing technology so as to construct more complex dynamic and static systems
2. To integrate SiC MEMS with SiC electronics into a single chip module
3. That the integrated system be capable of operating at high temperatures

To meet the above aims, the following objectives have been identified:

1. Design of a fabrication process for the integration of lateral accelerometers, pressure sensors and on-chip transistors in multilayer 3C SiC suitable for high temperature applications
2. Fabrication of transistors in 3C-SiC for interfacing and amplifying the output signal from a MEM structure
3. Fabrication of lateral accelerometers and pressure sensors in the silicon carbide layer using already optimised microfabrication techniques
4. Integration of the SiC sensors with SiC electronics into a single chip module
5. Testing of the resulting integrated microelectromechanical systems up to 800°C

To design and develop processes for making sensors for harsh environments, including automotive and aerospace applications; combustion processes or gas turbine control; oil industry.

• Design and fabrication processes have been developed and optimised for making thin film SiC pressure sensors. The sensors have been produced at the Scottish Microelectronics Centre and tested in our collaborator’s laboratory (GE Sensing Ltd). The devices show a sensitivity of 0.38e-3 (mV/V/mBar) when tested between -40 and 130 degrees C at two fixed pressure levels (0mBar and 700mBar).



• A possible reliability issue may lie in the thermal mismatch between the silicon substrate and the SiC thin film. Please see impact summary.



• Capacitive accelerometers were designed and fabricated.



• The mechanical properties of the SiC thin film have been evaluated through the testing of micro-fabricated cantilevers and bridges. The Young’s modulus of the SiC thin film has been measured to be ~ 330GPa, in addition, a temperature coefficient of Young’s modulus of -53ppm/K in the range room temperature (RT) to 300 degree C has been found, while an analytical expression is developed for the temperature range RT to 500 degrees C.