Local bonding environments of Si–OH groups in SiO2 deposited by remote plasma-enhanced chemical vapor deposition and incorporated by postdeposition exposure to water vapor

Abstract

We have deposited thin films of SiO2 by remote plasma-enhanced chemical vapor deposition and have identified similar infrared (IR) spectroscopic signatures of Si–OH groups incorporated during either film growth, or the cooling down process in the deposition chamber. These films can also be hygroscopic and, on postdeposition exposure to atmospheric water vapor, they show changes in the IR spectra associated with the incorporation of additional Si–OH groups. These changes are (i) the development of a new symmetric feature, centered at about 3350 cm−1, within the asymmetric O–H stretching band generated during growth and/or cooling down; (ii) the development of a new spectral feature at 925 cm−1; and (iii) a shift in the Si–O bond-stretching band to higher wavenumber. We show that the first two changes in the IR spectra are due to near-neighbor Si–OH bonding groups that result from the reaction between water vapor and the Si–O–Si bonds of the SiO2 host network. These spatially correlated Si–OH groups have different spectral features, due to relatively strong hydrogen bonding interactions, from the randomly distributed Si–OH groups that are incorporated initially during film growth and/or cooling down. The shift in the frequency of the Si–O stretching band derives from a preferential reaction of water with strained and highly reactive Si–O–Si bonding groups, i.e., those with the smallest Si–O–Si bond angles which are attacked by water vapor, resulting in the formation of near–neighbor pairs of Si–OH bonding groups.

Spatially Resolved EELS Fine Structures at a SiO2/TiO2 Interface

“…It is known that Si02 thermal oxides and evaporated films (which are porous) present differences : in the value of their refractive index in the visible, in the frequency of the dominant IRactive bond stretching vibration; this later varies according to the mean value of the bonding angle Si-O-Si between two tetrahedral Si04 and depends strongly on the deposition parameters [4,5]. Ellipsometry measurements have been performed during deposition, at a single wavelength (450 nm), and after deposition of each layer in the spectral range 400-800 nm.…”

Optimization of a Solution-Processed SiO2 Gate Insulator by Plasma Treatment for Zinc Oxide Thin Film Transistors

“…We propose that the new feature in the FTIR spectrum for the 80 W OCAPS is related to a reaction between the residual oxygen radicals on the OCAPS surface and the water in the surrounding environment [27][28] …”

Study of the Influence of Temperature on the Deposition of SiO₂ Films from Reaction of Silicone Oil Vapor and Ozone Gas

“…The line widths and the peaks position are same for all the deposition films. The broad absorption band for Si-O-Si bonds are 1010 -1090 cm -1 and 730 -860cm -1 , which are attributed to the Si-O-Si stretching and bending vibrations, respectively [35][36][37]. Thus, The peaks at the wavenumbers of 1075 cm -1 and 810 cm -1 are labeled as Si-O(1) and Si-O(2), respectively.…”