UNCOOLED THIN-FILM INFRARED IMAGING DEVICE WITH AEROGEL THERMAL ISOLATION - DEPOSITION AND PLANARIZATION TECHNIQUES

We have successfully integrated a thermally insulating silica aerogel thin film into a new uncooled monolithic thin film infrared (IR) imagi ng device. We have calculated noise equivalent temperature differences of 0.04-0.10 degrees C from a variety of PbxZryTi1-yO3 (PZT) and PbxL 1-xZryTi1-yO3 (PLZT) pyroelectric imaging elements in these monolithic structures. The low thermal conductivity of the aerogel films should also result in a significantly faster temporal response as well. Fabri cation of these monolithic devices entails sol-gel deposition of the a erogel, sputter deposition of the electrodes, and solution chemistry d eposition of the pyroelectric element. Consistent pyroelectric respons e across the device is achieved by use of appropriate deposition and p lanarization techniques of these three layers. Adjusting the chemistry and deposition process of the aerogel thin film had the greatest effe ct on large-scale uniformity and performance across the device. Sputte r depositing a planarization layer on top of the aerogel offered only minimal improvement in reducing surface roughness. However, using solu tion chemistry to deposit multiple thin coatings of PZT for the imagin g element resulted in a visible reduction in scattering and 80-100% pi xel yield. (C) 1998 Elsevier Science S.A. All rights reserved.