Remote Plasma Atomic Layer Deposition of SiNx Using Cyclosilazane and H₂/N₂ Plasma

Abstract

Silicon nitride (SiNx) thin films using 1,3-di-isopropylamino-2,4-dimethylcyclosilazane (CSN-2) and N₂ plasma were investigated. The growth rate of SiNx thin films was saturated in the range of 200-500°C, yielding approximately 0.38 angstrom/cycle, and featuring a wide process window. The physical and chemical properties of the SiNx films were investigated as a function of deposition temperature. As temperature was increased, transmission electron microscopy (TEM) analysis confirmed that a conformal thin film was obtained. Also, we developed a three-step process in which the H₂ plasma step was introduced before the N₂ plasma step. In order to investigate the effect of H₂ plasma, we evaluated the growth rate, step coverage, and wet etch rate according to H₂ plasma exposure time (10-30 s). As a result, the side step coverage increased from 82% to 105% and the bottom step coverages increased from 90% to 110% in the narrow pattern. By increasing the H₂ plasma to 30 s, the wet etch rate was 32 angstrom/min, which is much lower than the case of only N₂plasma (43 angstrom/min).