PSG(800nm)/$Si_3N_4$ (150nm)로 구성된 유전체 membrane 윗면에 heater와 감지전극을 등일면상에 동시에 형성하였다. 제작된 소자의 전체 면적은 $3.78{ imes}3.78mm^2$이고, diaphragm의 면적은 $1.5{ imes}1.5mm^2$이며, 감지막치 면적은 $0.24{ imes}0.24mm^2$였다. 그리고 diaphragm내의 열분포 분석을 유한요소법을 이용하여 수행하였으며, 실제로 제작된 소자의 열분포와 비교하였다. 소비전력은 동작온도 $350^{circ}C$에서 약 85mW였다. Sn 금속막을 상온과 $232^{circ}C$의 두 가지 기판온도에서 열증착하였고, 이를 $650^{circ}C$의 산소분위기에서 3시간 열산화함으로써 $SnO_2$ 감지막을 형성하였다. 그리고 이를 SEM과 XRD로 특성을 분석하였다. 제작된 소자에 대해서 온도 및 습도에 대한 감지막의 영향 및 부탄가스에 대한 반응특성도 조사하였다.
A micro-gas sensor with heater and sensing electrode on the same plane was fabricated on phosphosilicate glass(PSG, 800nm)/$Si_3N_4$ (150nm) dielectric membrane. PSG film was provided by atmospheric pressure chemical vapor deposition(APCVD), and $Si_3N_4$ film by low pressure chemical vapor deposition (LPCVD). Total area of the fabricated device was $3.78{ imes}3.78mm^2$. The area of diaphragm was $1.5{ imes}1.5mm^2$, and that of the sensing layer was $0.24{ imes}0.24mm^2$. Finite-element simulation was employed to estimate temperature distribution for a square-shaped diaphragm. The power consumption of Pt heater was about 85mW at $350^{circ}C$. Tin thin films were deposited on the silicon substrate by thermal evaporation at room temperature and $232^{circ}C$, and tin oxide films($SnO_2$) were prepared by thermal oxidation of the metallic tin films at $650^{circ}C$ for 3 hours in oxygen ambient. The film analyses were carried out by SEM and XRD techniques. Effects of humidity and ambient temperature on the resistance of the sensing layer were found to be negligible. The fabricated micro-gas sensor exhibited high sensitivity to butane gas.
