High Electron Mobility Germanium FinFET Fabricated by Atomic Layer Defect-Free and Roughness-Free Etching

Daisuke Ohori,Jenn-Hwan Tarng,Seiji Samukawa,Yao-Jen Lee,Takuya Fujii,Shuichi Noda,Yiming Li,Wataru Mizubayashi,Kazuhiko Endo

doi:10.1109/ojnano.2021.3055150

Abstract

We investigated a high electron mobility Ge FinFET fabricated by defect-free and roughness-free atomic layer neutral beam etching (NBE) compared with one fabricated by conventional plasma etching (PE). The etching interface roughness and defect were estimated by high-resolution transmission electron microscopy (TEM). In the case of using atomic layer defect-free NBE, the root-mean-square roughness of the Ge Fin sidewall surface is 1/3 times smaller than that using PE. Then, the electron mobility of Ge FinFET was improved by 1.65 times compared with that of a PE etched FinFET sample. For the subthreshold swing, the defect density of the interface between the Ge and gate dielectric film was improved by NBE. Ioff average currents of NBE and PE were around 18.1 and 57.6 nA/μm, respectively. As a result, NBE reduces the off-leakage current to 1/3 times less than PE. This corresponded to the differences in surface roughness and defect generation between NBE and PE. Therefore, we found that NBE could achieve a good performance by defect-free and atomically-flat etching the surface.

Highlights

Complementary metal-oxide-semiconductor (CMOS) devices with high performance and low energy consumption are required to achieve the development of a new smart society
We investigated the dependence of electron mobility and gate leakage current in the channel region on interface roughness and defects, especially on the side wall of a Fin structure fabricated by chlorine neutral beam etching (NBE) or plasma etching (PE)
Ge FinFET device is with high-k gate dielectric and TiN gate electrode etched by NBE and plasma etching

Summary

Introduction

Complementary metal-oxide-semiconductor (CMOS) devices with high performance and low energy consumption are required to achieve the development of a new smart society. We investigated the dependence of electron mobility and gate leakage current in the channel region on interface roughness and defects, especially on the side wall of a Fin structure fabricated by chlorine NBE or PE.

Results

Conclusion