Selective etching of Pt with respect to PtSi using a sacrificial low temperature germanidation process

Abstract

A soft and scalable etching procedure that selectively eliminates Pt without altering PtSi is proposed. The selective etch is based on the low temperature transformation of the excess Pt into a more reactive PtxGey phase that is easily etched in a sulfuric peroxide mixture. The mechanism of PtxGey alloying is detailed based on x-ray diffraction analysis. The innocuousness of the germanidation-based selective etch on the integrity of the PtSi∕Si junction is consolidated by Schottky barrier measurements. This process is expected to facilitate the integration and the scalability of PtSi on ultrathin silicon layers.