High Performance In-Zn-O FET with High On-current and Ultralow (<10−20 A/μm) Off-state Leakage Current for Si CMOS BEOL Application

We have demonstrated and experimentally verified the advantages of In-Zn-O (InZnO) channel compared with In-Ga-Zn-O (InGaZnO) channel for high performance oxide semiconductor channel field effect transistor (FET) with both ultralow off-state leakage current and high on-current. Compared with InGaZnO FET, high mobility (>30 cm2/Vs) and reduction of source/drain (S/D) parasitic resistance by 75% were achieved by InZnO FET. Analysis of a Schottky barrier height at S/D contact and a band offset between oxide semiconductor channel and gate insulator SiO2 revealed that the reduction of S/D parasitic resistance originated from a lowering of conduction band minimum by InZnO channel. Moreover, ultralow (<10−20 A/μm) off-state leakage current characteristics including not only S/D leakage current but also gate leakage current were confirmed to maintain even at thin gate insulator with an equivalent oxide thickness of 6.2 nm.