Status of 8.5μm pitch bolometer developments at Lynred

The development of a new thermometer material at Lynred has opened new opportunities towards a smaller pixel pitch. This pixel pitch reduction leads to several challenges and technological breakthroughs that are necessary both for the bolometer pixel design and the readout circuit architecture. The symposium presentation and the associated article will present a recent development at CEA-leti and Lynred of a 8.5μm bolometer pixel pitch Focal Plane Array (FPA). The drastic reduction of the pixel area leads to important changes of the micro bolometer features, especially a strong decrease of thermal capacitance Cth and increase of the thermal resistance Rth in order to maintain a high detector responsivity. The rise of the noise due to temperature fluctuation or 1/f contributions have also to be considered. The consequences of those modifications and resulting trade-offs, such as pixel fill factor and optical absorption yields in the 8-14 μm band ; pixel self-heating and Read-Out IC (ROIC) dynamic range, will be discussed. Finally, the electro-optical performances of our 640x480 FPAs are presented, and perspectives will be given.