The Optimized Design And Testing Of Hemt-Embedded Micro-accelerometers

The design and development of the micro-nano devices and systems based on new principles, new effects and new structures have become the research focus among the micro-nano electromechanical systems (M/NEMS) technology field. High electron mobility transistors(HEMT) belong to micro/nano-scale M/NEMS devices, which are fabricated by surface shallow junction process technology, possess multiple operating parameters and work areas, thus, the high sensitive detection can be realized by selecting appropriate work areas and parameters.Based on electromechanical conversion effect, optimized, fabricated and measurements of the HEMT-embedded micro-accelerometer structure are studied. First, the layout of the sensitive cell is modified and the micro-accelerometer structure based on GaAs HEMT is optimazed. Combing the process of surface micro-electronics and MEMS, theHEMT-embedded micro-accelerometers are successfully fabricated. The basic output characteristics, the gate groove depth effects on the electrical parameters and bias modulation of drain current's temperature drift coefficient of HEMT are studied. The results show that the performance of single-gate is better, the depth of gate groove have a certain impact on saturation current and threshold voltage, and the temperature drift coefficients of drain current are decided by the gate and drain voltage. Finally, the electromechanical detection effects of accelerometers are researched via static and dynamic test, including accelerometer's range, sensitivity, frequency response and the voltage bias of piezoresistive coefficient and sensitivity. The results show that the range of accelerometer is larger than the previous batch, and sensitivity is nearly equal; The frequency response of accelerometer is better below 500Hz, the piezoresistive coefficient and sensitivity strongly depend on the drain voltage and gate voltage.The HEMT-embedded micro-accelerometer provides a new test method for the micro-gravity, micro-displacement, pressure and other parameters; it also lays a certain foundation for the design and fabrication of high sensitivity micro-structures.