The Influence of Process Parameters on the Morphological Characteristics by Directional Etching for Materials Nanoarchitectonics

Abstract

In nanoarchitectonics, the advanced technology of directional etching is highly demanded for the fabrication of modern electronic device with high anisotropy ratio of structures. To facilitate the manufacturing processes, in this study we focus on establishing a phase-field model with a directional source term to simulate the dynamics of morphological formation and profile evolution in a crystalline substrate. Additionally, the influences of the etching rate, the degree of etching directionality, and the oblique angle on the structural characteristics are also taken into consideration to offer a broad perspective on the directional etching technologies. In the numerical analyses, the featured morphologies are elucidated by the dominant factors based on the mechanism of the profile evolution. The etched surface tends to be roughened with the crystallographic characters, while the kinetics of directional etching plays a prevailing role in the morphological formation. As the surface diffusion of substrate becomes a controlling factor, a flattened profile of the etched surface would be formed even in a condition of high directionality or high oblique angle. The featured surface morphologies, including the pyramid, ripple, mounds and etch pits, are reproduced numerically, and these simulation results correspond well with the observations of directional etching experiments. This study provides the fundamental knowledge and detailed information for the advanced application of the directional etching technology.