High mobility (&gt;30 cm² V⁻¹ s⁻¹) and low source/drain parasitic resistance In–Zn–O BEOL transistor with ultralow &lt;10−20 A <i>μ</i>m⁻¹ off-state leakage current

Abstract

We have demonstrated and experimentally verified the advantages of the In–Zn–O (InZnO) channel compared with the In–Ga–Zn–O (InGaZnO) channel for a high-performance oxide semiconductor channel field-effect transistor (FET) with both ultralow off-state leakage current and high on-current. Compared with the InGaZnO FET, high mobility (>30 cm2 V−1 s−1) and a reduction of source/drain (S/D) parasitic resistance by 75% were achieved by the InZnO FET. Analysis of the Schottky barrier height at the S/D contact and the band offset between the oxide semiconductor channel and gate insulator SiO2 revealed that the reduction of S/D parasitic resistance originates from the lowering of the conduction band minimum by the InZnO channel. Moreover, ultralow (<10−20 A μm−1) off-state leakage current characteristics including not only S/D leakage current but also gate leakage current were confirmed to be maintained even with a thin gate insulator with an equivalent oxide thickness of 6.2 nm.