Influence of plasma treatment on SiO2/Si and Si3N4/Si substrates for large-scale transfer of graphene

R Lukose,T Grabolla,F Akhtar,A Mai,M Lisker,M Fraschke,M Lukosius

doi:10.1038/s41598-021-92432-4

Abstract

One of the limiting factors of graphene integration into electronic, photonic, or sensing devices is the unavailability of large-scale graphene directly grown on the isolators. Therefore, it is necessary to transfer graphene from the donor growth wafers onto the isolating target wafers. In the present research, graphene was transferred from the chemical vapor deposited 200 mm Germanium/Silicon (Ge/Si) wafers onto isolating (SiO2/Si and Si3N4/Si) wafers by electrochemical delamination procedure, employing poly(methylmethacrylate) as an intermediate support layer. In order to influence the adhesion properties of graphene, the wettability properties of the target substrates were investigated in this study. To increase the adhesion of the graphene on the isolating surfaces, they were pre-treated with oxygen plasma prior the transfer process of graphene. The wetting contact angle measurements revealed the increase of the hydrophilicity after surface interaction with oxygen plasma, leading to improved adhesion of the graphene on 200 mm target wafers and possible proof-of-concept development of graphene-based devices in standard Si technologies.

Highlights

One of the limiting factors of graphene integration into electronic, photonic, or sensing devices is the unavailability of large-scale graphene directly grown on the isolators
Three types of S iO2 (HDP- S iO2, TEOS—SiO2, and thermal—SiO2) and one type of S i3N4 (PE-Si3N4) films were employed as target surfaces on standard Si wafers
HDP stands for high-density plasma deposition using silane (SiH4) precursor at 650 °C deposition temperature, TEOS is the deposition of SiO2 by using the tetraethyl(ortho)silicate (TEOS) precursor and plasma at 400 °C, whereas thermal S iO2 is produced at a temperature of 1000 °C. Si3N4 films were grown by plasma enhanced (PE) chemical vapor deposition at 400 °C by using silane and NH3/N2 gasses as precursors

Summary

Introduction

One of the limiting factors of graphene integration into electronic, photonic, or sensing devices is the unavailability of large-scale graphene directly grown on the isolators. The wetting contact angle measurements revealed the increase of the hydrophilicity after surface interaction with oxygen plasma, leading to improved adhesion of the graphene on 200 mm target wafers and possible proof-of-concept development of graphene-based devices in standard Si technologies. The intercalation with carbon m onoxide[13] or chemical modification[14] of the graphene-metal interface to achieve higher transfer speeds has been reported in the literature Another group of graphene transfer methods is based on chemical etching of the catalytic substrates on which graphene is grown. Different surface treatments lead to increased surface wettability as detected by measured wetting contact angle (WCA) measurements between solid surface and water drop This clearly shows the need for further investigations and understandings of the relation between surface wettability properties and the adhesion of graphene on the target wafers

Methods

Results

Conclusion