The development of x-ray bolometers based on SOI technology for astronomy

Abstract

Several successful development programs have been conducted on Infra-Red bolometer arrays at the French Atomic Energy Commission (CEA-LETI Grenoble), in collaboration with the CEA-Sap (Saclay); taking advantage of this background, we are now developing an X-ray spectro-imaging camera for next generation space astronomy missions, using silicon technology. We have developed monolithic silicon micro-calorimeters based on implanted thermistors. These micro-calorimeter arrays will be used for future space missions. A 8×8 array prototype consisting of a grid of 64 suspended pixels on SOI (Silicon On Insulator) has been created. Each pixel of this array detector is made of a tantalum (Ta) absorber and is bonded, by means of an indium bump hybridization process, to a silicon thermistor. The absorber array is bound to the thermistor array in a collective process step. The fabrication process of our detector involves a combination of standard silicon technologies such as Si bulk micromachining techniques, based on deposition, photolithography and plasma etching steps. Finally, we present the results of measurements performed on the different building elements and processes that are required to create a detector array up to 32*32 pixels in size.