Micromachined silicon thermopile and thermal radiators using porous silicon technology

A micromachined silicon thermopile and thermal emitters of infrared radiati on have been developed. The thermopile junction materials were highly doped polycrystalline silicon deposited by PECVD or RF sputtering and aluminum m etallisation. The hot junctions have been placed on a 0.5 mu m thick membra ne made of silicon nitride, and the cold junctions have been placed on a su rface of monolithic silicon. Porous silicon has been used as a thick sacrif icial layer to suspend the membrane over the cavity. Alternatively, nanopor ous silicon has been exploited as the thermal insulation material. Similar methods have been used for fabrication of electrically modulated microemitt ers of infrared radiation. This technology enables cost-effective manufactu ring of infrared thermal sensors, and high performance emitters.