Introduction of a High Selectivity Etching Process with Advanced SiNx Etch Gas in the Fabrication of FinFET Structures

Abstract

We evaluated the etching characteristics of a developed prototype hydrofluorocarbon-based SiNx etch gas. The developed gas has higher etching selectivity to poly-Si and SiO2 than conventional SiNx etch gases and a maximum selectivity of 62 to poly-Si and of over 100 to SiO2 were obtained. These highly selective etching chemicals are required for the development of three-dimensional Metal Oxide Semiconductor Field Effect Transistors (MOSFETs). In this work, we focused on Fin Field Effect Transistors (FinFETs), and in particular, FinFET structures that were fabricated by application of the developed gas to the gate spacer etch process. The FinFET structure fabricated with the developed gas is superior to that of the structure fabricated with CH3F, which is conventionally used for SiNx etching. We found that the developed gas is a promising etching gas for future high selectivity etching technologies.