Simulation of conformality of ALD growth inside lateral channels: comparison between a diffusion-reaction model and a ballistic transport-reaction model

Atomic layer deposition (ALD) has found significant use in the coating of high-aspect-ratio (HAR) structures. Approaches to model ALD film conformality in HAR structures can generally be classified into diffusion-reaction (DR) models, ballistic transport-reaction (BTR) models and Monte Carlo simulations. This work compares saturation profiles obtained using a DR model and a BTR model. The saturation profiles were compared qualitatively and quantitatively in terms of half-coverage penetration depth, slope at half-coverage penetration depth and adsorption front broadness. The results showed qualitative agreement between the models, except for a section of elevated surface coverage at the end of the structure, 'trunk', observed in the BTR model. Quantitatively, the BTR model produced deeper penetration into the structure, lower absolute values of the slope at half-coverage penetration depth and broader adsorption fronts compared to the DR model. These differences affect the values obtained when extracting kinetic parameters from the saturation profiles.

Automated summary

Atomic layer deposition (ALD) is widely used for coating high-aspect-ratio (HAR) structures. Different models, such as diffusion-reaction (DR) models, ballistic transport-reaction (BTR) models, and Monte Carlo simulations, have been developed to analyze the conformality of ALD films in HAR structures. This study compares the saturation profiles obtained from a DR model and a BTR model. The qualitative and quantitative comparison of these profiles reveals differences in penetration depth, slope, and adsorption front broadness between the two models.