Low-damage growth of Silicon Oxide by Remote Plasma Atomic Layer Deposition using CO2 Plasma

Abstract

High quality SiO2 film was deposited at low temperature by Plasma assisted Atomic Layer Deposition (PEALD) using Bis(diethylamino)silane precursor and CO2 plasma, which cause low damage to oxygen sensitive organic films compared to O2 plasma. Optical Emission Spectroscopy (OES) spectrum and PR ashing rate by plasma species was obtained to compare the plasma properties. The intensity of O radical at the OES spectrum at O2 plasma was clearly higher and therefore the Photoresist (PR) ashing rate of O2 plasma also was two times higher compared to CO2 plasma, which was respectively 8nm/min and 4nm/min. Self-limiting reaction of ALD growth of 1.04 ± 0.02 Å/cyc was obtained at 100℃ considering thermal budget of PR and other organic films. Moreover, film properties as atomic concentration, chemical bonding, density, growth rate was investigated to compare the PEALD SiO2 films deposited by CO2 and O2 plasma. Both of the SiO2 films showed a stoichiometry O/Si ratio of ~2.0 with impurity level of carbon content under 1% and an almost equivalent results at chemical composition. The density of the CO2 SiO2 film (2.25g/cm3), which is a sufficiently high density, was slightly lower than that of O2 SiO2 film (2.32g/cm3). The SiOH peaks of X-ray Photoelectron Spectroscopy (XPS) and Fourier-Transfer Infrared spectroscopy (FTIR) spectrum demonstrate deposition using CO2 plasma also follows the surface reaction of that of O2 plasma. These results indicate CO2 plasma is a suitable oxidant which can deposit SiO2 film with a sufficiently high-quality inducing low damages to the organic film.