Atomic Layer Deposition of Silicon Dioxide Using Aminosilanes Di-sec-butylaminosilane and Bis(tert-butylamino)silane with Ozone

Abstract

In situ Fourier transform infrared (FTIR) spectroscopy is used to investigate silicon dioxide deposition on OH-terminated oxidized Si(100) surfaces using two aminosilanes, di-sec-butylaminosilane (DSBAS) and bis­(tert-butylamino)­silane (BTBAS), with ozone as the coreactant. Both DSBAS and BTBAS readily react at 100 °C with surface −OH groups (loss at 3745 cm–1) with formation of Si–O–SiH3 and Si–O–SiH2–(NH t Bu), respectively, through elimination of secondary and primary amines. The (O−)­SiH3 structure is characterized by a strong Si–O–Si band at 1140 cm–1, and sharp (O−)­SiH3 stretch (2192 cm–1) and deformation (983 cm–1) bands. SiH3 remains stable up to 400 °C, at which point rearrangement into bidentate ((O−)2SiH2) and then tridentate ((O−)3SiH) bonding takes place through condensation reaction with neighboring OH or O groups. In contrast, the O–SiH2–(NH t Bu) structure obtained from BTBAS exposure at 100 °C loses its NH t Bu group at ∼350 °C, leading to a bidentate bonding ((O−)2SiH2) that remains stable up to 500 °C. In both cases, the transformation to bidentate and tridentate bonding depends on the initial OH concentration. The degree of ligand exchange during atomic layer deposition (ALD) with ozone also depends on the ozone flux. For a high enough flux (≥300 sccm, P ∼ 7.5 Torr), the ligand exchange is essentially complete, with the ozone pulse reacting with Si–H x [loss of vibrational bands at 2192 and 983 cm–1 for DSBAS, and at 2972, 2185, and 924 cm–1 for BTBAS] and forming surface Si–O–H (3745 cm–1). The initial Si–O–Si band at 1140 cm–1 broadens upon ozone exposure, consistent with the formation of a Si–O–Si network that extends the existing SiO2 substrate. In steady state, the ALD process is characterized by reaction of SiH x by ozone with the formation of OH, thus sustaining the ALD process, with densification of stoichiometric silicon oxide [transverse optical (TO) and longitudinal optical (LO) phonon modes at 1053 and 1226 cm–1].

Ultrathin Amorphous Silica Membrane Enhances Proton Transfer across Solid‐to‐Solid Interfaces of Stacked Metal Oxide Nanolayers while Blocking Oxygen

“…The FT‐IRRAS method provides the most detailed structural characterization of planar nanoscale oxide layers and interfaces because of its high surface sensitivity due to the electric field enhancement of perpendicularly polarized infrared modes, the ability to monitor signals from amorphous and crystalline phases alike, and to probe interfacial chemical bonds. The p‐polarized FT‐IRRAS of 2 nm SiO 2 samples reveals a characteristic, intense absorption of the longitudinal optic (LO) asymmetric SiOSi stretch mode at 1236 cm −1 with a shoulder at 1150 cm −1 (in‐ and out‐of‐phase motion of two adjacent O atoms with respect to the center Si atom) shown in Figure a. Interestingly, the corresponding transverse optic asymmetric ν(SiOSi) mode of amorphous silica wafers with a sharp peak at 1080 cm −1 is not observed because this mode cannot absorb p‐polarized light .…”

Design of efficient mono-aminosilane precursors for atomic layer deposition of SiO2 thin films

“…The formation of SiO-SiH 3 intermediate species had been conrmed by Peña et al using in situ Fourier transform infrared (FTIR) spectroscopy. 48 We rst focus on the reactivity of DIPAS, which has been experimentally examined, to understand the reaction mechanism of a Si precursor on the hydroxylated SiO 2 (001) surface. The optimized structures with the main structural parameters and energy variations for the dissociative reaction of DIPAS are shown in Fig.…”

Atomic‐Layer‐Deposited ZnO on Carbon Black as High‐Performance Catalysts for the Thermal Decomposition of Ammonium Perchlorate

“…In addition, Figure b shows a broad signal of the O 1s XPS spectrum for CB, which is deconvoluted into three components that can be ascribed to the contributions from C=O (530.8 eV), C–OH (532.2 eV), and –COOH (533.6 eV) . Meanwhile, the O 1s peak for ZnO/CB hybrids, shown in Figure e, shifts to the lower binding‐energy side, and the peak is resolved into four components.…”

“…At last, due to the effect of adsorbed H 2 O on the FTIR spectra, unfortunately, it is difficult to discriminate the broad bands of the O–H stretching mode and other groups that contained C–O bands at 3400 and 3450 cm –1 . [15b]…”

“…This likely originates from a reaction of DEZn with –OH, occurring on both C–OH‐ and –COOH‐terminated CB surfaces, to form C–O–Zn bonds. [14a], [15b]…”