Diamond Etching Beyond 10\u2009\u03bcm with Near-Zero Micromasking

Marie-Laure Hicks,Richard B Jackman,Alexander C Pakpour-Tabrizi

doi:10.1038/s41598-019-51970-8

Marie-Laure Hicks, Richard B Jackman + Show 1 more

Open Access

https://doi.org/10.1038/s41598-019-51970-8

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Abstract

To exploit the exceptional properties of diamond, new high quality fabrication techniques are needed to produce high performing devices. Etching and patterning diamond to depths beyond one micron has proven challenging due to the hardness and chemical resistance of diamond. A new cyclic Ar/O2 - Ar/Cl2 ICP RIE process has been developed to address micromasking issues from the aluminium mask by optimising the proportion of O2 in the plasma and introducing a preferential “cleaning” step. High quality smooth features up to, but not limited to, 10.6 μm were produced with an average etched surface roughness of 0.47 nm at a diamond etch rate of 45 nm/min and 16.9:1 selectivity.

Highlights

To exploit the exceptional properties of diamond, new high quality fabrication techniques are needed to produce high performing devices
This work investigated the use of an aluminium mask, chosen due to high selectivity and absence of carbide material formation that could cause sample contamination in an Argon/Oxygen Inductively Coupled Plasma (ICP) RIE process for diamond deep etching
As the plasma gas mix included increasing oxygen levels, from 10% to 30%, the diamond etch rate increased by 60%

Summary

Introduction

To exploit the exceptional properties of diamond, new high quality fabrication techniques are needed to produce high performing devices. Photoresists generally employed as masks in other semiconductor systems have insufficient lifetimes in the plasma to achieve significant etch depths in diamond, leaving metals or oxides as the main masking options[6,7,8]. These masking materials are known to generate micromasking, defects produced by sputtered mask particles across the etched surface. This work investigated the use of an aluminium mask, chosen due to high selectivity and absence of carbide material formation that could cause sample contamination in an Argon/Oxygen Inductively Coupled Plasma (ICP) RIE process for diamond deep etching. The process was subsequently evolved into a cyclic Ar/O2 and Ar/Cl2, reducing micromasking significantly and achieving smooth deep etching down to 10.6 μm

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