Theoretical Understanding of the Reaction Mechanism of SiO₂ Atomic Layer Deposition

Abstract

Atomic layer deposition (ALD) is a powerful nanofabrication technique for the preparation of uniform, conformal, and ultrathin films and allows accurate control of the composition and thickness of thin films at the atomic level. To date, ALD has been used for the growth of various materials, including oxides, nitrides, sulfides, metals, elements, compound semiconductors, and organic and organic–inorganic hybrid materials. As one of the most important inorganic materials, silicon dioxide (SiO2) has been used in the fields of microelectronics, catalysis, and energy storage and conversion. Various SiO2 ALD methods have been developed, which have expanded the research and applications of ALD chemistry and technology. Recent advances concerning the reaction mechanisms of SiO2 ALD have further deepened our understanding of the surface chemistry and related catalysis in the ALD of SiO2 and other oxides. Thin films of SiO2 can be obtained by means of thermal ALD and energy-enhanced ALD. Thermal ALD of SiO2 includes H2O-based ALD without a catalyst, room-temperature ALD (RT-ALD) catalyzed by a Lewis base, and rapid ALD (RALD) catalyzed by a Lewis acid. Energy-enhanced ALD of SiO2 encompasses plasma-enhanced ALD and O3-based ALD using aminosilane. In this review, we highlight the significance and advantages of ALD and introduce many methods of SiO2 ALD. Subsequently, theoretical advances concerning reaction mechanisms of SiO2 ALD are summarized. The related catalysis phenomena are highlighted, and their possible applications are speculated upon. Finally, a conclusion and perspective on the catalysis in the ALD growth of SiO2 is provided. It is expected that theoretical research on SiO2 ALD will enhance our comprehension of the chemistry and catalysis pertaining to ALD, provide a guide for the design of more effective Si precursors for SiO2 ALD, and lead to further improvement in the ALD preparation of other oxides and their nanolaminates.

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

“…[1][2][3] The ALD technique has been embraced by semiconductor manufacturers for new device fabrication and extensively used in microelectronics, optoelectronics, photonics, display technology, catalysis and coatings. 4 As one of the most essential materials in semiconductor industry, silicon dioxide (SiO 2 ) has been used in dynamic random-access memories (DRAMs) and complementary metaloxide semiconductors (CMOS) and eld-effect transistors (FET). 1,5 SiO 2 thin lms have been deposited with a variety of techniques.…”

“…[6][7][8] However, with the shrinkage of feature size and the growing demand for lms with high uniformity and conformality, ALD technique has been deemed to be the preferred deposition method at moderate temperature. 4 Efficient precursors for ALD techniques are of critical importance for deposition of high-quality thin lms at low temperature with low impurity levels. Among the Si precursors, such as Si halides, 9-11 alkoxides 12-14 and alkylamides, [15][16][17] alkylaminosilanes-based precursors have been shown to be superior to other types of materials due to their high reactivity at relatively low deposition temperature, high controllability for developing high density thin lms, and capability to offer relatively high growth rate.…”

“…Among the Si precursors, such as Si halides, 9-11 alkoxides 12-14 and alkylamides, [15][16][17] alkylaminosilanes-based precursors have been shown to be superior to other types of materials due to their high reactivity at relatively low deposition temperature, high controllability for developing high density thin lms, and capability to offer relatively high growth rate. 4,[18][19][20] There are two essential attributes for a viable precursor. First, the molecule must be chemically sufficiently stable so that decomposition does not occur prior to thin lm deposition.…”

Atomistic Simulations of Plasma-Enhanced Atomic Layer Deposition

“…In particular, the advent of modern density functional theory (DFT) based on accurate gradient-corrected and hybrid functionals allowed for the identification and understanding of elementary chemical reactions of a number of ALD processes [13]. For example, the understanding of SiO 2 ALD mechanisms has proceeded through a number of computational studies employing DFT [16]. The reactivities have been investigated for a number of aminosilane precursors [17,18,19,20,21,22,23], which display low activation energies for reactions with surface hydroxyl groups.…”

Growth of binary oxides on Si substrates: solid solutions of SiO2-GeO2 and HfO2-ZrO2

“…As one of the most important materials involved in silicon electronics, SiO 2 is unsurprisingly one of the most widely studied materials in the ALD literature, with several approaches that have been studied and optimized over the years [135]. The first reports of SiO 2 grown by ALD date back to the early 1970s, and many of them utilize halides, such as SiH 2 Cl 2 [136] or SiCl 4 [113,116,[137][138][139], as a silicon source.…”