Simple fabrication of an uncooled Al/SiO_2 microcantilever IR detector based on bulk micromachining

摘要

A simple microfabrication process to make an uncooled aluminum/silicon dioxide bi-material microcantilever infrared (IR) detector using silicon bulk micromachining technology is presented in this work. This detector is based on high banding of the microcantilever due to the large dissimilar in thermal expansion coefficients between the two materials. It consists of a 1 μm SiO_2 layer deposited by 200 nm thin Al layer. Since no sacrificial layer is used in this process, complexity related to releasing sacrificial layer is avoided. Moreover Al is protected in Si etchant using dual-doped tetramethyl ammonium hydroxide. The other advantage of this process is that only three masks are used with four photolithography process. Thermal and thermal mechanical behaviors of this structure are obtained using finite element analysis, and the maximum temperature and displacement at the end of cantilever at 100 pW/μm~2 absorbed IR power density on top surface are 7.82°K and 1.924 μm, respectively.