Nanomanufacturing of silicon surface with a single atomic layer precision via mechanochemical reactions

Lei Chen,Peng Zhang,Linmao Qian,Cheng Chen,Seong H Kim,Xinchun Lu,Jialin Wen,Bingjun Yu,Tianbao Ma

doi:10.1038/s41467-018-03930-5

Abstract

Topographic nanomanufacturing with a depth precision down to atomic dimension is of importance for advancement of nanoelectronics with new functionalities. Here we demonstrate a mask-less and chemical-free nanolithography process for regio-specific removal of atomic layers on a single crystalline silicon surface via shear-induced mechanochemical reactions. Since chemical reactions involve only the topmost atomic layer exposed at the interface, the removal of a single atomic layer is possible and the crystalline lattice beneath the processed area remains intact without subsurface structural damages. Molecular dynamics simulations depict the atom-by-atom removal process, where the first atomic layer is removed preferentially through the formation and dissociation of interfacial bridge bonds. Based on the parametric thresholds needed for single atomic layer removal, the critical energy barrier for water-assisted mechanochemical dissociation of Si–Si bonds was determined. The mechanochemical nanolithography method demonstrated here could be extended to nanofabrication of other crystalline materials.

Highlights

Topographic nanomanufacturing with a depth precision down to atomic dimension is of importance for advancement of nanoelectronics with new functionalities
The mechanochemical nanofabrication process on a Si(100) surface was conducted with scanning probe microscopy (SPM) using a silica microsphere probe (Supplementary Fig. 1) in ambient air with a relative humidity (RH) of 75% ± 2%
On the Si(100) surface, the theoretical thickness of monolayer is 1.36 Å (Fig. 1e), which is very close to the observed depth within the accuracy of SPM (Supplementary Fig. 2)

Summary

Introduction

Topographic nanomanufacturing with a depth precision down to atomic dimension is of importance for advancement of nanoelectronics with new functionalities. Similar to the well-known atomic layer deposition (ALD) process, ALE relies on sequential self-limiting thermal reactions; the only difference is that the final result is removal of a single atomic layer, instead of deposition All these methods require sacrificial masks for regio-selective patterning, which involve additional processing steps. Examples include localized deposition of organics through capillary flow (such as known as dip-pen lithography)[16,17], local deposition of polymer melts with a heated probe (which forms glassy organic resist upon cooling) 18,19, and localized electrochemical oxidation forming SiO2 masks[20,21] or reduction of graphene oxide at the nanoscale[22,23] using an electrically-biased tip In these approaches, the patterns produced with SPL can act as masks and the transfer of such patterns to the silicon substrate requires subsequent etching processes

Methods

Results

Conclusion