Fabrication and evaluation of a thermal sensor formed on a thin photosensitive epoxy membrane with low thermal conductivity

Abstract

This article present the fabrication and development of a thin metal film bolometer IR detector connected in a Wheatstone bridge configuration. The bolometer is constructed on a 4 mu m thin self-supported SU-8 2002 membrane. A polymer material such as SU-8 has low thermal conductivity and is applied using standard photolithographic processing step, and this could increase detector sensitivity and lower the production cost. Thermal simulation results are presented, which verifies SU-8 as a better choice of materials compared to common membrane materials such as Si and Silicon nitride. Measurements on the fabricated nickel resistance bolometer on SU-8 2002 membrane show a sensitivity of 9.3 V/W when radiated by an IR laser with a wavelength of 1.56 mu m.