Fabrication of Pt-polysilicon thin-film thermopiles: a preliminary study

A preliminary study is proposed aimed at developing a novel process for thin film thermopile detectors based on Pt-polysilicon thermoelements realized on a silicon substrate. Good contacts between Pt and heavily doped n and p-polysilicon have been achieved by using a Ti/TiN/Pt barrier structure. Step coverage of Pt on 300 nm high polysilicon steps obtained by RIE etching has been evaluated by wafer level measurements. The experimentally estimated process yield turns out to be higher than 90%. Mechanical stability of suspended dielectric structures covered with platinum has been evaluated by front-side micromachined test devices and the expected performance has been estimated by sensitivity tests on realized devices