Realisation of Silicon Microcalorimeters with Bulk Micromachining Technology

Abstract

Monolithic silicon micro-calorimeters consisting of a small suspended thermal mass that houses a highly sensible thermistor have been realised with the aid of bulk micro-machining techniques. An ad hoc post process module has been developed and adapted to the already optimised thermistor process. This micro-machining module is based on wet etchin steps, two of them been specially studied to this purpose. This process is characterised by two important features: 1) aluminium passivation together with a high anisotropy; 2) surface roughness control. All solutions are based on TMAH. A potential problem withi process are unstable edges and notching effects at the base of the supporting beams. Both problems can be overcome with a proper design of the device and a proper control of the etching time