This paper reports the fabrication of microbolometers using semiconducting YBaCuO as the IR sensing material. The detectors are operable at room temperature and thus are suitable for lost-cost and high performance imaging applications. Semiconducting YBaCuO is promising as a bolometric material as it has a thermal coefficient of resistance near 3% and relatively low noise. Two different bolometer structures will be reported here. First generation YBaCuO microbolometers were built on micromachined SiO$-2$/ bridges using wet etching techniques to undercut the silicon. The second generation structures were processed upon micromachined Si$-3$/N$-4$/ membranes with sputtered MgO films used as sacrificial layers. The membrane structures are the first of its kind to incorporate MgO as a sacrificial layer, and they offer a fabrication technique that is fully CMOS compatible, with all processing at ambient temperatures. Detectivities in the order of 10$+8$/ cm Hz$+$HLF$//W were measured at 30 Hz chopping frequency in both structures. The thermal conductance of the suspended membranes was on the order of 10$+$MIN@7$/ W/K, which is desirable as low thermal conductance yields high responsivities. There are realizable optimizations for both applications to yield detectivities over 10$+9$/ cm Hz $+$HLF$//W. All measurements reported here were performed at ambient temperature with no temperature stabilization.
展开▼
