초임계 이산화탄소와 HF 수용액을 이용한 고종횡비의 MEMS 구조물 건식 에칭기술 및 효율적인 건조법

Abstract

In this study, an effective dry etching method with high ratio micro electro mechanical systems (MEMS) structure using supercritical carbon dioxide was shown. The temperature, pressure, etching time, and hydrofluoric acid (HF) concentration of dry etching processing were investigated to sacrificial oxide in MEMS structure. The results indicated that cantilever beam was successfully etched to pattern wafer of 1:150 ratio without stiction. Drying processing optimum conditions were also investigated by changing temperature, pressure, drying time, CO2 flow rate and pulse. The concentration of isopropyl alcohol(IPA) at different temperature and pressure in drying process was obtained by volatile organic compounds (VOCs) analysis. The experiment data demonstrated the stiction phenomenon could be detected by using a high aspect ratio MEMS cantilever beam, and the aspect ratio increased to flow time. Additionally, the cantilever beam of the supercritical drying has 4 times longer than one of general wet-drying method. Furthermore, by adding the repetitive pulse in drying systems, a very well ratio (1:75) of MEMS structure could be obtained without stiction.