SUSPENDED SUPERCONDUCTOR MICROBOLOMETERS OPERATING AT THE TEMPERATUREOF LIQUID-NITROGEN - THEIR DESIGN AND MANUFACTURE BY MICROTOOLING OF SILICON SUBSTRATES

The sensitivity of a bolometer increases if the thermal conductance be tween the part of the sensor heated by the incident radiation and the heat sink decreases. Then, our work deals with the modelling and the f abrication of suspended YBaCuO microstructures by silicon micromachini ng. High quality YBaCuO films showing completely c-oriented texture an d single inplane epitaxial orientation were obtained on CeO2 / YSZ-buf fered Si substrates. Critical temperatures up to 88 K were measured fo r the as grown films. The micromachining technique using the Reactive Ion Etching (RIE) of silicon substrates was very reproducible. A therm al model was established on single suspended bridges and verified expe rimentally. The results enabled to optimise the detector geometry, a m eander constituted of 17 suspended bridges in series and covering a de tection surface of 100 x 100 mu m(2). The performances of the optimise d detector, measured at 85 K under irradiation from a blackbody. are a mong the best reported for YBaCuO micrometers (NEP = 4,0 10(-12) W roo t Hz arid detectivity = 2,5 10(9) cm root Hz / W, with a thermal time constant of 564 mu s). The etching of Separated by Implanted Oxygen (S IMOX) substrates enabled to fabricate suspended membranes constituting of the YBaCuO / CeO2 (/)YSZ / Si multi-layers and then to obtain an a dditional liberty degree in the membrane composition.