Influence of Hydrogen Incorporation on the Structure and Stoichiometry of Chemically Vapor Deposited Silica Films

Abstract

Hydrogen incorporation into SiO 2 films grown by low-pressure chemical vapor deposition (CVD) from SiH 4 /O 2 mixtures is investigated by means of infrared spectroscopy (IRS), nuclear magnetic resonance (NMR), elastic recoil detection analysis (ERDA), X-ray photoemission spectroscopy (XPS), and nuclear reaction analysis (NRA). We find that hydrogen atoms are preferentially bonded to O atoms, forming bulk SiOH groups, either isolated or clustered, and H 2 O groups, with a minor incorporation of SiH groups, as well as geminal and surface isolated SiOH groups. The proportion of clustered SiOH groups decreases upon increasing the deposition temperature, which has been attributed to the faster dehydroxylation reactions and higher surface mobility of the hydrogenated species involved in the film growth. Using a novel method based on the combination of NRA and ERDA, we verify quantitatively that the predominance of O-H over Si-H bonding implies a slight overstoichiometric character (O/Si atomic ratio > 2) that is accentuated with increasing OH concentration.

Enhancement of breakdown strength of SrTiO3/nano-SiO2 composite film prepared by sol-gel technology

“…4 shows the FT-IR spectra of (1-x)SrTiO 3 /xSiO 2 composite thin films. The peaks at 640 cm -1 and 1112 cm -1 are corresponding to the stretching vibration modes of Ti-O and Si-O-Si bonds, respectively [22][23][24]. The peak at 1450 cm -1 can be assigned to the chemisorbed CO 2 molecules, while the peak at 2350 cm -1 is closely related to the physisorbed CO 2 molecules [25].…”

Nebulization of Nanocolloidal Suspensions for the Growth of Nanocomposite Coatings in Dielectric Barrier Discharges

“…However, the weak signal of the H 2 ‐O bending mode at 1625 cm −1 and the strong presence of the bending vibrations of Si‐OH at 930 cm −1 indicate that the amount of absorbed water on the coating is small. Therefore, the wide band in the 3650–3520 cm −1 range is assigned to the Si‐OH groups in the matrix or located on the surface, having interactions with their chemical environment …”

“…Therefore, the wide band in the 3650-3520 cm À1 range is assigned to the Si-OH groups in the matrix or located on the surface, having interactions with their chemical environment. [47] The amount of organic moieties in the film is minor because of the absence of the C-H vibrations normally detected in the 2850-2930 range and the Si-CH 3 symmetric vibration at 1260 cm À1 . However, a minor amount of C5 5N and/or C5 5O is detected around 1650 cm À1 .…”

Hydrogen Elimination Kinetics during Chemical Vapor Deposition of Silica Films

“…The OH:SiOSi bond ratio in the film was obtained from the ratio between the areas behind the O-H and Si-O-Si stretching absorbance bands (found at 3760 and 1070 cm -1 , respectively), according to the procedure described elsewhere. 24 The stretching Si-H absorption band, typically located at 2250 cm -1 in silica, 25 was always absent in our IR spectra. Therefore, the OH:SiOSi ratio (accounting for both SiOH and H 2 O species) was considered to be a good measure of the total hydrogen concentration incorporated in the film.…”

“…In a recent paper we have reported the influence of hydrogen incorporation on the structure and stoichiometry of silica films grown by SiH 4 /O 2 CVD. 24 The present work focuses on a kinetic analysis of the mechanisms that limit hydrogen elimination during this deposition process under mass-transport and reactionrate limited growth regimes. To this end, we have analyzed jointly the influence of the experimental parameters on deposition rate and hydrogen concentration in the film.…”