Comparative investigation on organosilicon film growth by cyclonic plasma using hexamethyldisilazane and hexamethyldisilazane/nitrogen gas mixture

Abstract

This study aimed to discover the surface characteristics of cyclonic plasma‐deposited films and the effect of nitrogen gas addition. The influence of nitrogen gas addition on the surface characteristics of organosilicon films in hexamethyldisilazane (HMDSN) and HMDSN/nitrogen (HMDSN/N2) cyclonic plasmas at atmospheric pressure was evaluated. It was found that the addition of nitrogen gas is a crucial factor affecting organosilicon film growth in the plasma cyclone in one atmosphere. SEM, AFM, and ATR‐FTIR results indicated that on adding nitrogen gas, the surface morphology became rougher, the peak corresponding to the Si–O–Si group was detected at approximately 1050 cm−1, the degree of porosity was relatively low, and the proportion of the SiCHx group decreased. In general, the surface energies of the films deposited in the HMDSN discharge and the HMDSN/N2 gas mixture discharge exhibited similar features. SEM and AFM evaluations showed high roughness values of 44.5 nm for the film formation in the HMDSN/N2 gas mixture discharge, while the films grown in the HMDSN discharge exhibited a relatively flat surface with a roughness of 24.5 nm. Based on ATR‐FTIR detection, cyclonic plasma‐deposited films deposited in the HMDSN discharge obtained organic moieties, while the films generated in the HMDSN/N2 gas mixture discharge exhibited strong Si–O–Si absorption signals. A possible nano‐organosilicon film growth that prevails in atmospheric pressure plasma deposition is proposed based on atmospheric‐pressure plasma chemistry, nitrogen gas addition, and experimental observations.