Cu(Ge) alloy films with zirconium addition on barrierless Si for excellent property improvement

Abstract

This paper reports the superior properties of Cu(Ge,Zr) films deposited by cosputtering on barrierless Si substrates. After being annealed, a self-forming ZrGex/Cu3Ge layer and a ZrOx (ZrSiyOx)/Cu3Ge layer, respectively, are formed during a sequence of solid-state reactions between the Cu(Ge,Zr) layer and adjacent layers and they could effectively hinder mutual diffusion between Cu and Si, presenting at the interface of the Cu/Cu(Ge,Zr)/Si film stacks. Leakage current and resistivity evaluations reveal the excellent thermal reliability of this Cu(Ge,Zr) film at temperatures up to 650 °C, suggesting its potential application in advanced barrierless Cu metallization. The mechanisms involved are analysed based on detailed characterization studies.