Highly C‐axis Aligned ALD‐InGaO Channel Improving Mobility and Thermal Stability for Next‐Generation 3D Memory Devices

Abstract

AbstractA way to obtain highly ordered and thermally stable crystalline In–Ga–O (IGO) thin films is reported by atomic layer deposition with novel bulky dimethyl[N‐(tert‐butyl)−2‐methoxy‐2‐methylpropan‐1‐amine] gallium precursor. The optimal cation composition for IGO (In:Ga = 4:1 at%) shows a pronounced alignment along the high c‐axis with cubic (222) orientation at a relatively low annealing temperature of 400 °C. Moreover, the crystallinity and oxygen‐related defects persist even at elevated annealing temperatures of 700 °C. Owing to its well‐aligned crystallinity, the optimal IGO thin film transistor demonstrates extremely high field‐effect mobility (µFE) and remarkable thermal stability at high temperatures of 700 °C (µFE: 96.0 → 128.2 cm2 V−1s−1). Also, process‐wise, its excellent step coverage (side: 96%, bottom: 100%), compositional uniformity in a 40:1 aspect ratio structure, superior crystal growth in vertical structures, and excellent reproducibility make it a promising candidate for application as a channel in next‐generation 3D memory devices.