Uncooled micromachined bolometer arrays on flexible substrates

This paper reports progress on the development of micromachined infrared microsensors on flexible polymer substrates. The flexible substrates were formed by spin-coating polyimide films (HD Microsystems PI-5878G) on silicon wafer carriers. Semiconducting Yttrium Barium Copper Oxide (YBCO) was used as the thermistor. The microbolometer was fabricated using a polyimide (HD Microsystems PI2737) sacrificial mesa and titanium electrode arms. The YBCO thermistor was suspended above the substrate by the electrode arms after the sacrificial layers have been removed by micromachining. The polyimide substrate was then removed from the silicon wafer carrier to complete the fabrication of the infrared microsensors on a flexible polyimide substrate. The measured thermal conductance of the microbolometers ranged from 9.07 x 10(-6) W/K for a non-micromachined to 4.0 x 10(-7) W/K for a micromachined sensor. As a result, the responsivity and detectivity were measured to be as high as 6.1 x 10(4) V/W and a 1.2 x10(8) cmHz(1/2)/W, respectively, with a 970 nA current bias. This level of performance is comparable to similar micromachined detectors fabricated on silicon substrates.