Thin Film Growth Model Research Articles

Stochastic model for thin film growth and erosion

A linearized, stochastic theory of thin film growth and erosion is presented to describe the evolution of surface roughness in the case of good layer formation far from equilibrium, as is generally found in energetic growth techniques such as ion-assisted vapor deposition. The variation of the power spectral density and root-mean-square roughness is studied for growth on smooth and rough substrates.

Epitaxial chemically vapour deposited Si 1− xGe x thin film growth at very low total pressure

Experimental results obtained by Jang and Reif (S. M. Jang and R. Reif, Appl. Phys. Lett., 59 (1991) 3162; 60 (1992) 707) with respect to total Si 1− x Ge x growth rate dependence on silane as well as germane input rate at a deposition temperature of 893 K and total pressures in the range from 0.4 Pa to 1.3 Pa are analysed and re-interpreted. Re-interpretation is based on a previously published model of composite thin film growth that considers Si 1− x Ge x total growth rate to be the sum of three partial growth rates. The model succeeds in explaining the main trends of the experimental observations, when additional silicon deposition in Si 1− x Ge x thin film growth is considered to be enhanced by the germane content of the gas phase and hampered by the germanium atom density on the layer surface.

Models of thin film growth

Abstract Two models of 3D film growth, which incorporate the basic ideas of various models previously published, were created. These models were formulated in differential quantities in order to be able to analyse their results from the point of view of film morphology. The derived morphological characteristics are compared with experimental data.

Three-dimensional computer simulations of high-T c epitaxial film growth

A three-dimensional Monte Carlo model of the anisotropic thin film growth has been developed. The model assumes on-lattice positioning of growth units and directional interaction between them, it takes into account processes of reevaporation and thermal hopping of the growth units, and involves anisotropic bond energies as parameters. Using this model the dependences of the film morphology on the substrate temperature and supersaturation can be computed. The model allows one to explain experimentally observed complicated transformations of the surface morphology as the substrate temperature is varying. It also allows one to predict the preferential orientation of the growing film and the density of defects.

Structural anisotropy in oblique incidence thin metal films

A three-dimensional ballistic deposition model for thin film growth has been developed, incorporating the mechanisms of shadowing and relaxation which are essential to microstructure formation. In addition to generating columnar structure similar to that found in films deposited at low temperature, the simulation produces columns which become elliptic cylinders as the angle of incident vapor flux is increased. The model clearly confirms that this structural anisotropy which develops in the film plane is due to self-shadowing in the growing film. The anisotropy, originally revealed in magnetic and electrical properties of obliquely deposited alloys, appears as the elongation of column structure in a direction perpendicular to the plane of incidence. In agreement with titanium films sputtered using a planar magnetron at 65 mPa argon pressure, simulations show a maximum ratio of column major axis to minor axis of about 2 at a deposition angle of 60°. The effect is seen to decrease in both simulations and real films at higher angles of incidence.

A two-dimensional Monte Carlo model for thin film growth by oblique evaporation: simulation of two-component systems for the example of CoCr

Starting from the well-known idea of atomic shadowing during thin film growth ( i.e. ballistic aggregation) a two-dimensional computer model is developed which includes surface relaxation by thermally induced surface diffusion and atomic attraction for a two-component system. An attempt was made to link the model interaction energies to real bonding energies in CoCr thin films. The model was applied to investigate structural as well as local configuration changes in the aggregates during systematic parameter variations.

The effects of surface diffusion on the growth of thin film

A thin film growth model with the consideration of transient nucleation was proposed to simulate the vapor deposition process onto solid surface. This model is based on the mechanism of surface diffusion of adatoms, and the adatom concentration distribution is obtained by solving the diffusion equation around stable clusters The computation procedure is divided into a sequence of time stages in order to solve the time dependent problem. The cluster density and cluster size distribution can thus be obtained in every time stage. The results show that the transient stage can not be neglected for the case of completed condensation. The effect of adatoms consumption by stable clusters is important only in the later stage of the process when a significant number of stable clusters are formed. The effects of substrate temperature on the nucleation rate and the cluster growth are also discussed.

Ballistic deposition simulation of via metallization using a quasi-three-dimensional model

A quasi-three-dimensional ballistic deposition model for thin film growth by physical vapor deposition is described. This model incorporates three-dimensional incident flux distributions and shadowing effects, but simulates deposition through disc accretion in a two-dimensional plane. Results from the simulation of sputtered metal deposition over vias ranging from 0.5 to 3.0 mu m width are presented and compared with two-dimensional simulation results. Step coverages are calculated and plotted as a function of via size. The use of a ballistic deposition program enables a density analysis of the simulated films. The simulated films display a drop in density of 22-27% for the films deposited on the via sidewalls, and this density drop is plotted versus via size for both the two-dimensional and three-dimensional simulations. >

Continuum model of thin-film deposition and growth.

A continuum theory for the deposition and growth of solid films is presented. The theory is developed in a coordinate-independent manner and so incorporates the fully nonlinear physics. The evolution of the film is modeled in three steps. First, the adsorption of atoms in the incident beam is modeled as a ballistic process. Second, the random motion of the adatoms is treated as a diffusive process. Finally, sticking of adatoms to the film occurs as a Poisson process. The resulting system of differential equations is examined in several parameter limits. The diffusively dominated limit appears similar to zone 1 of the structure-zone model. Generically the surface slope develops discontinuities; these ``kinks'' play the role of grain boundaries. In the ballistically dominated case these kinks may be advected along the surface giving rise to columnarlike microstructures, as is observed in zone 2.

Thin film nucleation kinetics

Abstract The saturation nucleus density, calculated on the basis of the nucleation and initial thin film growth model due to Routledge and Stowell (1970), is described in simple analytical form. An approximate formula is derived which can be used in a straightforward manner to analyse experimental data, and an example of such an analysis is given.