Atomic Layer Etching in Patterning Materials: Anisotropy, Selectivity, Specificity and Sustainability

Abstract

Continued advances in semiconductor manufacturing depend on the 3D integration of complex materials, with nano-scaling precision patterning being a key limiting factor. This article discusses several important aspects of plasma-surface interactions to support atomic scale precision in patterning novel materials. This includes the effect of ions that control the etch anisotropy, the role of surface chemistry that dictates reaction specificity and etch selectivity, and the broader impact of the plasma applications on chemical processing sustainability. A systematic approach is discussed for developing an atomic layer etch process, which allows for independent control of surface modification and product volatilization at low temperatures. This approach starts with predicting a plausible etch product and thermodynamic screening of possible reaction mechanisms, choosing the appropriate half-cycle reactants, leveraging chemical reactivity, and counterbalancing etch and deposition as possible pathways of achieving greater selectivity. This can be followed by experimental verification of the etch rates, product formation, and etch selectivity. Finally, it discusses how these ALE processes can be leveraged to enhance the overall chemical processing sustainability.