Ripple Formation during Oblique Angle Etching

Mehmet F Cansizoglu,Tansel Karabacak,Mesut Yurukcu

doi:10.3390/coatings9040272

Abstract

Chemical removal of materials from the surface is a fundamental step in micro- and nano-fabrication processes. In conventional plasma etching, etchant molecules are non-directional and perform a uniform etching over the surface. However, using a highly directional obliquely incident beam of etching agent, it can be possible to engineer surfaces in the micro- or nano- scales. Surfaces can be patterned with periodic morphologies like ripples and mounds by controlling parameters including the incidence angle with the surface and sticking coefficient of etching particles. In this study, the dynamic evolution of a rippled morphology has been investigated during oblique angle etching (OAE) using Monte Carlo simulations. Fourier space and roughness analysis were performed on the resulting simulated surfaces. The ripple formation was observed to originate from re-emission and shadowing effects during OAE. Our results show that the ripple wavelength and root-mean-square roughness evolved at a more stable rate with accompanying quasi-periodic ripple formation at higher etching angles (θ > 60°) and at sticking coefficient values (Sc) 0.5 ≤ Sc ≤ 1. On the other hand, smaller etching angle (θ < 60°) and lower sticking coefficient values lead to a rapid formation of wider and deeper ripples. This result of this study can be helpful to develop new surface patterning techniques by etching.

Highlights

Morphological evolution of surfaces during thin film deposition [1] has been the interest of many researchers for applications in industries including micro- and nano- electronics and mechanical systems [2]
In order to explore the evolution of the surface morphology during oblique angle etching (OAE), we developed Monte Carlo (MC) simulations that consider shadowing [24,25,26], re-emission, and noise effects [23]
A visual comparison in Figure 2 indicates that the surface morphology moved towards a rippled structure elongated in the beam direction as the sticking coefficient sticking coefficient values (Sc) is increased

Summary

Introduction

Morphological evolution of surfaces during thin film deposition [1] has been the interest of many researchers for applications in industries including micro- and nano- electronics and mechanical systems [2]. [21] has investigating the effect ofsurface surfaceroughness charging of onplasma-etched the surface roughness plasma‐etched reviewed Ono experimental andhas simulation studies on the surface evolution plasma substrates. Reviewed experimental and morphology simulation studies on during the surface etching, which reported ripple formation under the presence of obliquely incident energetic ions. Carried out an experimental and simulation investigation of ripple of obliquely incident energetic ions. By controlling etching the beam of zero‐kinetic energy etching particles is film highly directional and the shadowing effect through the angle of etching particles with non-unity sticking coefficients, it is obliquely incident on the film surface. To allowInzero-kinetic-energy modify a conventional plasma etching simulation method to allow zero‐kinetic‐energy obliquely obliquely incident particles that leads to the OAE simulations.

Monte Carlo Simulations

Results and Discussion

Simulated

Proposed of ripple formation during

Dynamic Evolution Roughness and Ripple Wavelength during OAE

Conclusions