실리콘 Piezoresistive 압력센서 제작공정에 관한 연구
(A) Study on the Fabrication Process of Silicon Piezoresistive Pressure Sensor
정보제어공학과 박막재료 및 소자 전공
실리콘 Piezoresistive 압력센서 제작공정;
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In this study, Si anisotropic etching characteristics of tetra methyl ammonium hydroxide(TMAH)/ammonium persulfate(AP)/isopropyl alcohol (IPA) solutions were investigated to realize the optimum structure of a diaphragm for the piezoresistive pressure sensor application. Due to its low toxicity and its high compatibility with the CMOS processing, TMAH was used as Si anisotropic etchants. The variations of Si etch rate on the etching temperature, TMAH concentration, and etching time were obtained. With increasing the etching temperature and decreasing TMAH concentrations, the Si etch rate is increased while a significant non-uniformity exists on the etched surface because of formation of hillocks on the (100) surface. The addition of IPA to TMAH solution leads to smoother etched surfaces but, makes the Si etch rate lower. However, with the addition of AP to TMAH solution, the Si etch rate is increased and an improvement in flatness on the etching front is observed. The Si etch rate is also maximized with increasing the number of addition of AP to TMAH solution per one hour. The Si square membranes of 20㎛thickness and 100~400㎛one-side length were abricated successfully by applying optimum Si etching conditions of TMAH/AP solutions.