[labnetwork] Diamond Etching

[Mohammad Soltani]

Hi Emma

We have been working on etching single crystal diamonds (normally 3*3 mm or 2*2 mm with 300um to 500um thickness from element6).
We usually use ICP RIE of Oxygen plasma with masks like Ti/Al/SiN/HSQ; the ICP powers vary depending on the etching process but are generally above 700 with an RF power of more than 100. The Cleaning recipe we used in QNFCF is O2/SF6.
Based on my experience, there shouldn't be a contamination issue related to diamond etching itself.
Also,  I used a Silicon Pocket (etched area in silicon wafer) as a silicon carrier piece, which might make it easier to handle diamonds.

Best,
Mohammad Soltani
-----------------------------------
Postdoctoral Fellow
Institute for Quantum Computing (IQC).
University of Waterloo, 200 University Avenue West,
Waterloo, Ontario, Canada.
Office: QNC 2209
Email: m9soltan at uwaterloo.ca<mailto:m9soltan at uwaterloo.ca>

________________________________
From: labnetwork <labnetwork-bounces at mtl.mit.edu> on behalf of Emma Anquillare <eanquillare at gc.cuny.edu>
Sent: Wednesday, July 31, 2024 12:26 PM
To: Labnetwork (labnetwork at mtl.mit.edu) <labnetwork at mtl.mit.edu>
Subject: [labnetwork] Diamond Etching

Hello Lab network!

We have a user that is interested in etching a CVD grown slab of Diamond (Area: 3mmx3mm) about ~300 um thick via CF4/O2 or SF6 plasma (CF4 process described here-
 https://www.sciencedirect.com/science/article/abs/pii/S0925963501006173<https://urldefense.com/v3/__https://www.sciencedirect.com/science/article/abs/pii/S0925963501006173__;!!GekbXoL5ynDpFgM!WxaE7hfA6-iCIfo3iRBj8F1Agt1XD-R1rG2Erff2xgbqNr8azLuLPVme0Bu1-MPWWvbxOATSjMfwV6cW23nVbunPXr7k$> , though they would use a SiO2/ PMMA instead of Al mask and an ICP instead of an RIE).

Here is what I have read on diamond so far:
There is no precedent category for Carbon or diamond in the Cornell CNF materials categories (though SiC was allowed in even the most restricted tools) or in labnetwork. The sputter yield should be very low (~0.2 with Xe at 750ev- though most of the other values we have for comparison were with Ar at 600eV) and I could not find a vapor pressure curve for it. MP/BP at atmosphere is absurdly high (in the thousands) and I don't think the etch temperature would be hot enough for it to degrade to graphite. (Actually- I don't even know if our etcher will get hot enough to prompt the fluorine reaction based on literature, but apparently it has been etched before.) Not a toxic material. We might get HF vapor as a side product but usually figure scrubbers can handle that without further risk or precautions.

Do any facilities out there have experience plasma etching CVD diamond? What level-of-cleanliness tool did you allow it in? Were there any contamination problems (especially relevant to waveguides) or other safety aspects I should be aware of? What cleaning recipe did you use?

Thanks,
Emma









_____________________________________________
Emma Anquillare, PhD
Research Scientist
ASRC Nanofabrication Facility
City University of New York

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