A snapshot review on metal-semiconductor contact exploration for 7-nm CMOS technology and beyond

Abstract

Contact resistances take a significant portion of on-state resistances of advanced Si CMOS transistors. As a result, a metal-semiconductor contact resistivity (rho(c)) of sub-10(-8) Omega.cm(2) or even sub-10(-9) Omega.cm(2) is required to achieve high performance for a very downscaled transistor. In this snapshot review on our rho(c) investigation efforts, we first introduce a test structure-a multiring circular transmission line model (MR-CTLM)-with high accuracy to measure ultralow rho(c), and then we evaluate different contact solutions. Our contact solution exploration includes metal/insulator/semiconductor (MIS) contacts for n(+)-Si and advanced (gemano-)silicides for n(+)-Si and p(+)-SiGe. We will discuss limitations of MIS contacts. And we will demonstrate encouraging rho(c) of 10(-9) Omega.cm(2) that meet the requirement of 7-nm or 5-nm CMOS technology nodes.