Uncooled amorphous silicon technology: high performance achievement and future trends

The emergence of uncooled infrared detectors has opened new opportunities for IR imaging both for military and civil applications. Infrared imaging sensors that operate without cryogenic cooling have the potential to provide the military or civilian users with infrared vision capabilities packaged in a camera of extremely small size, weight and power. Uncooled infrared sensor technology has advanced rapidly in the past few years. Higher performance sensors, electronics integration at the sensor, and new concepts for signal processing are generating advanced infrared focal plane arrays. This would significantly reduce the cost and accelerate the implementation of sensors for applications such as surveillance or predictive maintenance. We present the uncooled infrared detector operation principle and the development at CEA/LETI from the 256 x 64 with a pitch of 50 mum to the 320 x 240 with a pitch of 35 gym. LETI has been involved in Amorphous Silicon uncooled microbolometer development since 1992. This silicon IR detection is now well mastered and matured so that industrial transfer of LETI technology was performed in 2000 towards Sofradir. Industrial production of 320 x 240 microbolometer array with 45 mum pitch is then started., we present the readout circuit architectures designs and its evolution from the 256 x 64 array to the different version of 320 x 240 arrays. Electro-optical results obtained from these IRCMOS are presented. NEDT close to 30 mK is now obtained with our standard microbolometer amorphous silicon technology.