Improvement of structural stability and IR detecting characteristics of microbolometer

Abstract

A rounded-shape sacrificial layer side-wall and multi-layer of IR detecting layer composed of vanadium/vanadium oxide/vanadium were demonstrated for uncooled type microbolometer fabrication using surface micromachining technology. The improvement of structural stability of floating microbolometer structure was achieved by reducing supporting bridge angle up to 50 degrees. Also smoothly rounded bridge allows more efficient residual stress releasing and flatness of floating structure without distortion. The rounded side-wall shape reduces stress concentration of wall edge and was achieved by plasma treatment of sacrificial polyimide. The IR detecting characteristics was also improved by means of fabricating an IR active layer having a high TCR with low resistivity. We deposited multi-layer of vanadium oxide film as an IR detecting layer by-a layer-by-layer technology, which fabricates a sandwich typed or multi-layered vanadium and vanadium oxide using conventional r.f. magnetron sputtering system. We easily obtained over -2%/K of TCR and 1 Omega -cm of resistivity of VOx films by new deposition technique.