Analytical model for island growth in atomic layer deposition using geometrical principles

Abstract

Island growth has been shown to also occur for atomic layer deposition (ALD) processes. This article presents a relatively simple analytical model using geometrical principles with few independent variables on evolution of thickness and roughness in island-dominated ALD processes. The model is well suited for the fitting of experimental data to extract parameters such as density of islands and growth rate. It allows islands of various shapes, but most of the attention here is devoted to cone and hemispherical shaped islands in a hexagonal grid on a flat substrate. For a selection of cases, exact analytical expressions are derived. The model shows that it is possible to reproduce the growth characteristics of substrate-inhibited growth of both types 1 and 2 with a suitable choice of functional form of the islands. Finally it is compared with previously advanced models describing substrate-inhibited growth.

Nucleation period, surface roughness, and oscillations in mass gain per cycle during W atomic layer deposition on Al2O3

“…Several simulations of ALD nucleation have recently explored the expected MGPC and roughness using various models and assumptions. [22][23][24][25][26] This study has extended the previous work on W / Al 2 O 3 nanolaminates by using high resolution QCM studies to examine the nucleation of W ALD on Al 2 O 3 surfaces and Al 2 O 3 ALD on W surfaces during the growth of W / Al 2 O 3 nanolaminates. Al 2 O 3 ALD is one of the most thoroughly investigated ALD processes.…”

“…26 Simulations of island growth during ALD nucleation have recently been presented based on numerical and analytical methods. [22][23][24][25] The simulations predict that the MGPC or "film-mean-growth" 22,25 will vary considerably versus the number of ALD cycles. The position of the local maxima of the MGPC is dependent on the initial number of islands or "seed objects."…”

“…The position of the local maxima of the MGPC is dependent on the initial number of islands or "seed objects." 22,25 When there are fewer initial islands, the local maxima occurs after larger numbers of ALD cycles. The size of the local maxima of the MGPC compared with the steady state MGPC is fairly constant versus the number of initial islands.…”

Molecular dynamics simulation of the Al2O3film structure during atomic layer deposition

“…Unfortunately, as with many physical and chemical processes, the overall ALD growth is too complex to be fully modelled by using precise electronic structure calculations, and hence we need simulation methods that can extend the time and length scales accessible in our simulations. Along this line, the ALD growth dynamics have been simulated previously using lattice kinetic Monte Carlo (LKMC) simulations [15,16] and continuous analytical models [17,18]. However, all of these models are based on approximations of the bulk geometries of the thin films, and hence sacrifice important atomic-level information, such as critical information about the interface structure.…”

Dynamic Modeling for the Design and Cyclic Operation of an Atomic Layer Deposition (ALD) Reactor

“…Results of such studies have been combined with kinetic Monte Carlo (kMC) simulations to quantify nucleation [14] and growth [15,16] kinetics. Empirical growth models have also been developed to describe ALD kinetics during the initial stages of nucleation [17,18] and island growth [19][20][21]. Additionally, surface reaction models have been developed to predict growth kinetics and the effects of operating parameters (e.g., temperature, pressure, precursor exposure time) during undersaturating conditions and leading to self-limiting ALD growth [11,[22][23][24][25].…”