Mapping the effect of substrate temperature inhomogeneity during microwave plasma-enhanced chemical vapour deposition nanocrystalline diamond growth

Leigh, William G.S., Cuenca, Jerome A. ORCID: https://orcid.org/0000-0003-1370-1167, Thomas, Evan L.H., Mandal, Soumen ORCID: https://orcid.org/0000-0001-8912-1439 and Williams, Oliver A. ORCID: https://orcid.org/0000-0002-7210-3004 2023. Mapping the effect of substrate temperature inhomogeneity during microwave plasma-enhanced chemical vapour deposition nanocrystalline diamond growth. Carbon 201 , pp. 228-337. 10.1016/j.carbon.2022.09.036

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Abstract

It is important to account for variance in substrate temperature during microwave plasma-enhanced chemical vapour deposition (MPECVD) nanocrystalline diamond growth, as this has a significant impact on the uniformity of the grown film. In this work, an in-situ method of mapping the substrate temperature under MPECVD growth conditions is demonstrated, employing a mirror galvanometer to scan the field of view of a dual-wavelength pyrometer across the substrate. Temperature maps generated were compared to plasma electron densities simulated using a finite element model. An increase in temperature and simulated plasma density were seen towards the centre of the holder. The properties of nanocrystalline diamond films were mapped using ex-situ Raman spectroscopy and spectroscopic ellipsometry (SE). A greater SE-measured bulk thickness and bulk sp3 fraction, as well as a greater first-order diamond Raman intensity and lower full width at half maximum were seen in the higher-temperature central region, demonstrating the impact of substrate temperature inhomogeneity during growth. The temperature mapping technique demonstrated allows easy evaluation of the impact of substrate holder design, microwave power and chamber pressure on substrate temperature homogeneity, and therefore optimisation of growth conditions for uniform diamond film growth.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Physics and Astronomy
Publisher:	Elsevier
ISSN:	0008-6223
Funders:	EPSRC
Date of First Compliant Deposit:	22 September 2022
Date of Acceptance:	9 September 2022
Last Modified:	06 Jan 2024 02:37
URI:	https://orca.cardiff.ac.uk/id/eprint/152788

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