Platinum silicide contacts to silicon by lift‐off

摘要

Thin layers of platinum silicide, interposed between heavily doped silicon junctions and a thick overlying interconnect metallization, assure that good ohmic contact characteristics prevail. In conventional processes the thin PtSi film is formed by reacting a thin (200–500 A˚) sputtered Pt film with the underlying silicon substrate. The unreacted platinum that is found on the surrounding field oxide area is then etched in aqua regia. This self‐aligned process may pose some problems with regard to the integrity of the Pt/Si contact and the device yield. For these reasons we have studied an alternative Pt deposition‐patterning scheme that promises to alleviate the seriousness of these problems. PtSi contacts have been fabricated by means of a new photoresist lift‐off technique. The aim of the present study is to contrast this new lift‐off process for the formation of PtSi contacts to Si with the conventional self‐aligned technique. Our results indicate that the new process is preferred although it gives rise to somewhat higher values for the contact resistance.