A high fill-factor infrared bolometer using micromachined multilevel electrothermal structures

A high fill-factor uncooled infrared (IR) bolometer has been fabricated by using thin-film titanium resistors sandwiched in a surface-micromachined silicon oxinitride membrane (50 /spl mu/m/spl times/50 /spl mu/m). This bolometer is realized in multilevel electrothermal structures with a fill-factor over 92%. From the multilevel structure, thermal isolation can be independently optimized without sacrificing IR absorbing area. Initial measurements show a thermal time constant of 12 ms, a responsivity of 1600 V/W, and a detectivity (D*) of 5/spl times/10/sup 8/ cm/spl radic/Hz/W.