Measurement results of a 12 μm pixel size microbolometer array based on a novel thermally isolating structure using a 17 μm ROIC

In this paper a novel concept for the fabrication of highly sensitive uncooled microbolometers is presented. The approach is based on the realization of thermal isolation and simultaneous electrical contacting of the microbolometers by means of sufficiently long and thin coated nanotubes, which can be fabricated by post processing on top of CMOS wafers comprising the ROIC. Thus, the effective area of the absorption layer is maximized at a given pixel size, as lateral legs, which have been the main component of the thermal isolation commonly, are completely omitted. The resulting thermal conductivity can be tuned independently from the pixel size by varying the geometry and structuring of the nanotubes. Based on test structures the nanotube microbolometers are characterized with respect to electro-optical and mechanical properties. The focus in this paper is on nanotube microbolometers with a pixel size of 12 μm.