Inner Spacer Engineering to Improve Mechanical Stability in Channel-Release Process of Nanosheet FETs

Khwang-Sun Lee,Jun-Young Park

doi:10.3390/electronics10121395

Abstract

Mechanical stress is demonstrated in the fabrication process of nanosheet FETs. In particular, unwanted mechanical instability stemming from gravity during channel-release is covered in detail by aid of 3-D simulations. The simulation results show the physical weakness of suspended nanosheets and the impact of nanosheet thickness. Inner spacer engineering based on geometry and elastic property are suggested for better mechanical stability. The formation of wide contact area between inner spacer and nanosheet, as well as applying rigid spacer dielectric material, are preferred.

Highlights

As logic technology continues scaling for smaller chip size, better output performance, and low static power consumption, channel geometry in field-effect transistors (FETs) have evolved from planar to nanowire structures, as is well known
In the case of an n-type nanosheet FETs (NS FETs), a few nanometers of inner spacer is deposited between the nanosheets
Most reports related with inner spacer have been performed in terms of electrical performance [20,21,22,23,24]

Summary

Introduction

As logic technology continues scaling for smaller chip size, better output performance, and low static power consumption, channel geometry in field-effect transistors (FETs) have evolved from planar to nanowire structures, as is well known. Inner Spacer Engineering to Improve Mechanical Stability in Channel-Release Process of Nanosheet FETs. Electronics 2021, 10, 1395. Due to the limitation of nanowire perimeter in GAA FETs, vertically stacked structures comprising multiple silicon nanowires or nanosheets have been preferred for wider effective channel width [2,3,4]. Discussions on mechanical stability and implementing improvements seem timely in the development of NS FETs. In this work, for the first time, the impact of gravity during fabrication processing of NS FETs is demonstrated.

Results

Conclusion