Reliable Nanofabrication of Single-Crystal Diamond Photonic Nanostructures for Nanoscale Sensing

TL;DR

This paper presents a reliable top-down nanofabrication process for single-crystal diamond photonic structures, enhancing adhesion and process reliability for nanoscale sensing applications.

Contribution

Introduction of a novel silicon inter-layer to improve adhesion and avoid damage during nanofabrication of diamond photonic structures.

Findings

Enhanced adhesion of resist to diamond using silicon layer

Silicon layer can be selectively removed without damaging the nanostructures

Refined fabrication process increases reliability for sensor device manufacturing

Abstract

In this manuscript, we outline a reliable procedure to manufacture photonic nanostructures from single-crystal diamond (SCD). Photonic nanostructures, in our case SCD nanopillars on thin (< 1$\mu$m) platforms, are highly relevant for nanoscale sensing. The presented top-down procedure includes electron beam lithography (EBL) as well as reactive ion etching (RIE). Our method introduces a novel type of inter-layer, namely silicon, that significantly enhances the adhesion of hydrogen silsesquioxane (HSQ) electron beam resist to SCD and avoids sample charging during EBL. In contrast to previously used adhesion layers, our silicon layer can be removed using a highly-selective RIE step which is not damaging HSQ mask structures. We thus refine published nanofabrication processes to ease a higher process reliability especially in the light of the advancing commercialization of SCD sensor devices.