Wide process temperature of atomic layer deposition for In2O3 thin-film transistors using novel indium precursor (N,N'-di-tert butylacetimidamido)dimethyllindium

Abstract

This study introduces a novel heteroleptic indium complex, which incorporates an amidinate ligand, serving as a high-temperature atomic layer deposition (ALD) precursor. The most stable structure was determined using density functional theory and synthesized, demonstrating thermal stability up to 375 degrees C. We fabricated indium oxide thin-film transistors (In2O3 TFTs) prepared with DBADMI precursor using ALD in wide range of window processing temperature of 200 degrees C, 300 degrees C, and 350 degrees C with an ozone (O3) as the source. The growth per cycle of ALD ranged from 0.06 to 0.1 nm cycle(-1 )at different deposition temperatures. X-ray diffraction and transmission electron microscopy were employed to analyze the crystalline structure as it relates to the deposition temperature. At a relatively low deposition temperature of 200 degrees C, an amorphous morphology was observed, while at 300 degrees C and 350 degrees C, crystalline structures were evident. Additionally, x-ray photoelectron spectroscopy analysis was conducted to identify the In-O and OH-related products in the film. The OH-related product was found to be as low as 1% with an increase the deposition temperature. Furthermore, we evaluated In2O3 TFTs and observed an increase in field-effect mobility, with minimal change in the threshold voltage (V (th)), at 200 degrees C, 300 degrees C, and 350 degrees C. Consequently, the DBADMI precursor, given its stability at highdeposition temperatures, is ideal for producing high-quality films and stable crystalline phases, with wide processing temperature range makeing it suitable for various applications.