Atomic layer chemical vapor deposition of SiO2 thin films using a chlorine-free silicon precursor for 3D NAND applications

Atomic layer deposition and atomic layer chemical vapor deposition (ALD, ALCVD) of SiO2 films were investigated over a wide range of high temperatures (from 525 °C to 700 °C) using chlorine-free amino silane as the Si precursor and O3 as the oxygen reactant. The ALD window occurred at 550–600 °C. The growth per cycle (GPC) of the SiO2 films was about 1.14–1.58 A/cycle for deposition temperatures between 525 and 700 °C. There were no chlorine impurities detected in any of the deposited ALCVD films. Above a deposition temperature of 750 °C, the SiO2 films exhibited conventional chemical vapor deposition (CVD) behavior due to precursor decomposition, as evidenced by high GPC (5.51 A/cycle) and a significant impurity content (carbon 0.2 at% and nitrogen 0.4 at%). The SiO2 films had high film density (2.3 g/cm3), minimal roughness (rms ~ 0.16 nm). In addition, the wet etch rate (WER) of the SiO2 films decreased from 3.0 to 2.1 nm/min. The ALD SiO2 film at 600 °C exhibited excellent electrical performance, such as a leakage current density of 5.03 × 10−9 A/cm2 (at 3 MV/cm) and a breakdown field of 10.3 MV/cm.