Lattice Monte Carlo models of thin film deposition

Gilmer, George H.; Huang, Hanchen; Rubia, T. Dı́az de la; Torre, J. Dalla; Baumann, F.H.

doi:10.1016/s0040-6090(99)01057-3

Cited by 121 publications

(75 citation statements)

References 22 publications

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“…In this process, islands with the surface that offers the longest adatom residence time, i.e., lowest diffusivity, have a higher probability to trap adatoms that diffuse on both sides of a grain boundary. 10,11 Those islands thus capture more adatoms and overgrow all other islands. This leads to the development of a preferred out-ofplane orientation, while leaving the in-plane orientation unaffected, i.e., random.…”

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confidence: 99%

Double in-plane alignment in biaxially textured thin films

Elofsson

Saraiva

Boyd

et al. 2014

Applied Physics Letters

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The scientific interest and technological relevance of biaxially textured polycrystalline thin films stem from their microstructure that resembles that of single crystals. To explain the origin and predict the type of biaxial texture in off-normally deposited films, Mahieu et al. have developed an analytical model [S. Mahieu et al., Thin Solid Films 515, 1229 (2006)]. For certain materials, this model predicts the occurrence of a double in-plane alignment, however, experimentally only a single in-plane alignment has been observed and the reason for this discrepancy is still unknown. The model calculates the resulting in-plane alignment by considering the growth of faceted grains with an out-of-plane orientation that corresponds to the predominant film out-of-plane texture. This approach overlooks the fact that in vapor condensation experiments where growth kinetics is limited and only surface diffusion is active, out-of-plane orientation selection is random during grain nucleation and happens only upon grain impingement. Here, we compile and implement an experiment that is consistent with the key assumptions set forth by the in-plane orientation selection model by Mahieu et al.; a Cr film is grown off-normally on a fiber textured Ti epilayer to pre-determine the out-of-plane orientation and only allow for competitive growth with respect to the in-plane alignment. Our results show unambiguously a biaxially textured Cr (110) film that possesses a double in-plane alignment, in agreement with predictions of the in-plane selection model. Thus, a long standing discrepancy in the literature is resolved, paving the way towards more accurate theoretical descriptions and hence knowledge-based control of microstructure evolution in biaxially textured thin films.

Funding Agencies|Linkoping University

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confidence: 99%

Double in-plane alignment in biaxially textured thin films

Elofsson

Saraiva

Boyd

et al. 2014

Applied Physics Letters

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Funding Agencies|Linkoping University

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“…4 -22 In our previous studies, it has been demonstrated that the dominance of ͗111͘ texture is a result of two-dimensional growth at initial stage, that is the formation of large ͕111͖ facets. 23,24 The large facet is the direct consequence of small adatom migration barrier and nearly zero conventional-hereafter referred to as the two-dimensional ͑2D͒-Schwoebel-Ehrlich barrier in aluminum. Our ensuing studies show that the 2D Schwoebel-Ehrlich barrier is also very small for dimers and trimers diffusing down a ͕111͖ facet in aluminum.…”

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confidence: 99%

Schwoebel-Ehrlich barrier: from two to three dimensions

Liu

Huang

Woo

2002

Applied Physics Letters

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107

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The Schwoebel-Ehrlich barrier-the additional barrier for an adatom to diffuse down a surface step-dictates the growth modes of thin films. The conventional concept of this barrier is two dimensional ͑2D͒, with the surface step being one monolayer. We propose the concept of a three-dimensional ͑3D͒ Schwoebel-Ehrlich barrier, and identify the 2D to 3D transition, taking aluminum as a prototype and using the molecular statics method. Our results show that: ͑1͒ substantial differences exist between the 2D and 3D barriers; ͑2͒ the transition completes in four monolayers; and ͑3͒ there is a major disparity in the 3D barriers between two facets; further, alteration of this disparity using surfactants can lead to the dominance of surface facet against thermodynamics. © 2002 American Institute of Physics. ͓DOI: 10.1063/1.1475774͔Texture has been a recognized factor that controls the performance of thin films. For example, the ͗111͘ texture of aluminum interconnects in integrated circuits dictates their resistance to electromigration, 1 and ͗100͘ texture of TiN is preferred in mechanical coating.2,3 The Schwoebel-Ehrlich barrier is a key factor in surface processing. 4 -22 In our previous studies, it has been demonstrated that the dominance of ͗111͘ texture is a result of two-dimensional growth at initial stage, that is the formation of large ͕111͖ facets. 23,24 The large facet is the direct consequence of small adatom migration barrier and nearly zero conventional-hereafter referred to as the two-dimensional ͑2D͒-Schwoebel-Ehrlich barrier in aluminum. Our ensuing studies show that the 2D Schwoebel-Ehrlich barrier is also very small for dimers and trimers diffusing down a ͕111͖ facet in aluminum. 25 On the other hand, both experiments 26 and Wulff construction show that two large facets meet each other and form a ridge, as shown in Fig. 1. The intersection of two large facets is also common under normal deposition conditions; when deposition rate is not too high or substrate temperature is not too low. 23 For exchange of atoms between two such facets, an adatom has to cross over the ridge, effectively diffusing down a surface step of multiple layers; the SchwoebelEhrlich barrier is therefore 3D. During a growth process, a facet may not be so flat, and surface steps can be of one, two, or many layers. As a result, the Schwoebel-Ehrlich barrier experiences a gradual transition from 2D to 3D. For clarity, we define the Schwoebel-Ehrlich barrier as the total energy barrier over a step or a ridge; in contrast to the extra energy barrier when only a 2D case is considered.The molecular statics method is described in detail in reference, 25 and will be briefly summarized here. A simulation cell with a flat surface, say ͕111͖, ͕110͖, or ͕100͖, is first chosen. An island of multiple layers is introduced on top of the flat surface. The island is constructed so that the top surface is parallel to the substrate, and the side surfaces consist of ͕100͖, ͕110͖, and ͕111͖ facets. A typical simulation cell a͒ Corresponding author; electro...

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“…[84,85,89,124] Since different low-index surfaces possess different surface diffusivities, the stabilization of facets leads to a competitive growth of certain grains. [125,126] For fcc metals such as Au and Ag, the {111} surface typically has a much higher diffusivity than the {110} or {100}. [127][128][129] This makes a {111} surface grow laterally, as atoms tend to diffuse quickly to the edges of the facet and cross the step there, while the other two surfaces will grow more outwards due to the longer residence time of atoms on these surfaces.…”

Section: Morphological Growth Transitionsmentioning

confidence: 99%

Dynamics of the Early Stages in Metal-on-Insulator Thin Film Deposition

Lü¹

2014

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Thin films consist of nanoscale layers of material that are used in many technological applications to either functionalize a surface or serve as parts in miniaturized devices. The properties of a film are closely related to its microstructure, which in turn can be tuned during film preparation. Thin film growth involves a multitude of atomic-scale processes that cannot always be easily studied experimentally. Therefore, different types of computer simulations have been developed in order to test theoretical models of thin film growth in a highly controlled way. To be able to compare simulation and experimental results, the simulations must be able to model events on experimental time-scales, i.e. several seconds or minutes. This is achievable with the kinetic Monte Carlo method.In this work, kinetic Monte Carlo simulations are used to model the initial growth stages of metal films on insulating, amorphous substrates. This includes the processes of island nucleation, three-dimensional island growth and island coalescence. Both continuous and pulsed vapor fluxes are investigated as deposition sources, and relations between deposition parameters and film morphology are formulated. Specifically, the film thickness at what is known as the "elongation transition" is studied as a function of the temporal profile of the vapor flux, adatom diffusivity and the coalescence rate. Since the elongation transition occurs due to hindrance of coalescence completion, two separate scaling behaviors of the elongation transition film thickness are found: one where coalescence occurs frequently and one where coalescence occurs infrequently. In the latter case, known nucleation behaviors can be used favorably to control the morphology of thin films, as these behaviors are not erased by island coalescence. Experimental results of Ag growth on amorphous SiO 2 that confirm the existence of these two "growth regimes" are also presented for both pulsed and continuous deposition by magnetron sputtering. Knowledge of how to avoid coalescence for different deposition conditions allows nucleation for metal-on-insulator material systems to be studied and relevant physical quantities to be determined in a way not previously possible. This work also aids understanding of the growth evolution of polycrystalline films, which in conjunction with advanced deposition techniques allows thin films to be tailored to specific applications.ii iii PREFACE

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Lattice Monte Carlo models of thin film deposition

Cited by 121 publications

References 22 publications

Double in-plane alignment in biaxially textured thin films

Double in-plane alignment in biaxially textured thin films

Schwoebel-Ehrlich barrier: from two to three dimensions

Dynamics of the Early Stages in Metal-on-Insulator Thin Film Deposition

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