| 초록 |
Ultra-thin (20㎛) silicon strain gauges were fabricated with silicon-on-insulator (SOI) wafer by a wet etching process. Buffered oxide etchant (BOE, NH4F: HF =6:1) solution was used for wet etching process in which the etching temperature was kept at 50℃. Photoresist as a passivation layer protecting from a chemical etchant attack was deposited on the upper part of SOI wafer on which strain gauges are designed. Small amounts of octylamine and octanol were added in the BOE solution to improve the surface wettability and etching selectivity of SiO2/Si. The fabricated strain gauges were attached on the sensor diaphragm and its pressure sensing properties were investigated. The resistance changed linearly with tensile and compressive stress. The maximum values of non-linearity and hysteresis error were -0.341% and 0.909%, respectively. Thermal coefficient of resistance (TCR) and sensitivity were 4,128 ppm/℃ and 34.22 mV/V, respectively. It is concluded that the ultra-thin Si strain gauge prepared with the SOI wafer by a wet etching is well applicable for the pressure-sensitive membrane of sensor, especially at high hydrogen pressure range. |
