Understanding the intrinsic compression in polycrystalline films through a mean-field atomistic model

TL;DR

This paper introduces a mean-field atomistic model to explain the atomic-scale mechanisms behind intrinsic stress buildup in polycrystalline films, aligning well with experimental nanoscale stress measurements.

Contribution

It develops a mean-field rate-equation model that captures the atomic mechanisms of adatom buildup and predicts intrinsic stress behavior during film growth.

Findings

Model estimates of surface stress profiles match experimental data.

Stress depends on temperature and deposition flux.

The approach bridges mesoscopic theory and atomic-scale physics.

Abstract

Mullins' theory predicts the buildup of adatoms during surface diffusion at the edges of grooves where grain boundaries emerge to the surface of a polycrystalline film. However, the mesoscopic nature of this theory prevents the identification of the atomic scale physical mechanisms involved in this phenomenon. Here, we interpret the buildup of adatoms in atomistic terms through a mean-field rate-equation model and demonstrate both its kinetic nature and its impact on the intrinsic stress in these systems. Furthermore, the model provides estimates of the surface profile of intrinsic stress, of its typical mean values, and of the dependence of stress on temperature and deposition flux for different growth stages. These estimates agree well with reported experimental results obtained from recent advances in nanoscale mapping of mechanical stresses on the surface of polycrystalline films.