Design and fabrication of cooled silicon bolometers for mm wave detection

CEA has a long history of customizing optoelectronic components for space and astronomy applications. With this expertise we are undertaking a development of cooled silicon bolometers for millimeter (mm) wave polarization detection, typically at $\lambda =1.5$ mm, in order to address the next generation of space astronomy missions. This work presents the early results on the design and fabrication of an innovative pixel operating at very low temperature between 50 and 100 mK. This pixel is using a Ti/TiN thin film absorber and an ion-implanted silicon thermometer which exhibits a very small heat capacity and a very low 1/f noise at low temperature. This sensor is implemented on a standard SOI substrate. We performed a 2D process simulation of the silicon thermometer and an electromagnetic simulation of the pixel absorption to obtain good performances at low temperature. We present R(T) electrical characterizations of simplified silicon thermometers at low temperature showing a variable range hopping (VRH) model dominating effect. The model prediction shows a good agreement with experimental results.