Low temperature NbSi thin film thermometers on Silicon Nitride membranes for bolometer applications

We report the design of amorphous NbSi thin film bolometer thermometers on Silicon Nitride membranes. Due to the low-thermal conductivity of Si3N4, this material has several applications in millimeter wavelength bolometers and microcalorimetry. Compared to NTD-Ge thermometers, similar sensitivities are obtained with a 50 times lesser volume. The smallest realized films have a rectangular surface (100×400 μm2) and are 100 nm thick. Optimization of the thermometer shape, NbSi composition and electrical material contact is discussed. The goal of this development is to manufacture a complete array of bolometers by photolithography techniques.