Plasma-enhanced atomic-layer-deposited indium oxide thin film using a DMION precursor within a wide process window

Abstract

In this study, we developed a new liquid indium precursor, dimethyl[N-(tert-butyl)-2-methoxy-2-methylpropan-1-amine] indium (DMION), to deposit indium oxide films using the plasma-enhanced atomic layer deposition (PEALD) method. The indium oxide films were deposited using DMION and Ar/O2 plasma as the precursor and reactant, respectively, with relatively high growth per cycle (GPC, ∼1.2 Å/cycle) within a wide atomic layer deposition (ALD) window (35–300 °C). Impurities such as carbon and nitrogen were not detected regardless of the deposition temperature. The crystallinity of the films had a bixbyite cubic structure within the ALD window and facets could be controlled by deposition temperature modulation; (400) facets were dominant at low deposition temperatures (35 and 100 °C), whereas (222) facets were dominant at high deposition temperatures (200 and 300 °C). The dominant facets and orientations of the indium oxide crystal were maintained until 400 °C in the post-annealing process. The thin-film transistors (TFTs) using indium oxide deposited at 200 °C exhibited high field-effect (∼32.1 cm2/Vs) mobility with a reasonable threshold voltage (∼1.8 V) and subthreshold voltage swing (∼0.48 V/decade).