Dynamic evolution of internal stress, grain growth, and crystallographic texture in arc-evaporated AlTiN thin films using in-situ synchrotron x-ray diffraction

TL;DR

This study uses in-situ synchrotron x-ray diffraction to simultaneously analyze the evolution of texture, grain size, and internal stress in arc-evaporated AlTiN thin films, revealing how these properties change with film growth and substrate temperature.

Contribution

It is the first to concurrently monitor texture, grain size, and microscopic stress evolution in polycrystalline thin films during deposition.

Findings

Stress inversely correlates with grain size beyond 14 nm.

Immediate compressive stress relaxation occurs as film thickness increases.

Distinct growth regimes identified based on stress evolution.

Abstract

Understanding the nucleation and growth of polycrystalline thin films is a long-standing goal. Polycrystalline films have many grains with different orientations that affect thin-film properties. Numerous studies have been done to determine these grain size and their preferred crystallographic orientation as well as stress in films. However most past studies have either employed an ex-situ methodology or only monitor the development of macroscopic stress in real-time. There has never been any research done on the simultaneous determination of crystallographic texture, grain size, and microscopic stress in polycrystalline thin films. In this study, we simultaneously monitored the generation and temporal evolution of texture, grain size, and internal stress in cathodic arc evaporated Al0.50Ti0.50N thin films using a bespoke deposition apparatus designed for use with 2-dimensional synchrotron x-ray diffraction technique. The influence of the substrate temperature is investigated in terms of the emergence and development of texture, grain size and stress evolution. A dynamic evolution of the crystallographic texture is observed as the overall film thickness varies. We clearly resolved two regime of films growth based on stress evolution. Beyond a threshold grain size (~ 14 nm), the stress scales inversely to the average grain sizes, and as the film thickness increases, immediate compressive stress relaxation was seen. An extensive ex-situ evaluation of thin films using electron microscopies and electron diffraction was performed to support the in-situ x-ray diffraction results.