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Material and optical properties of low-temperature NH3-free PECVD SiNx layers for photonic applications

Material and optical properties of low-temperature NH3-free PECVD SiNx layers for photonic applications
Material and optical properties of low-temperature NH3-free PECVD SiNx layers for photonic applications
SiNx layers intended for photonic applications are typically fabricated using LPCVD and PECVD. These techniques rely on high-temperature processing (>400 °C) to obtain low propagation losses. An alternative version of PECVD SiNx layers deposited at temperatures below 400°C with a recipe that does not use ammonia (NH3-free PECVD) was previously demonstrated to be a good option to fabricate strip waveguides with propagation losses <3dB cm-1. We have conducted a systematic investigation of the influence of the deposition parameters on the material and optical properties of NH3-free PECVD SiNx layers fabricated at 350°C using a design of experiments methodology. In particular, this paper discusses the effect of the SiH4 flow, RF power, chamber pressure and substrate on the structure, uniformity, roughness, deposition rate, refractive index, chemical composition, bond structure and H content of NH3-free PECVD SiNx layers. The results show that the properties and the propagation losses of the studied SiNx layers depend entirely on their compositional N/Si ratio, which is in fact the only parameter that can be directly tuned using the deposition parameters along with the film uniformity and deposition rate. These observations provide the means to optimise the propagation losses of the layers for photonic applications through the deposition parameters. In fact, we have been able to fabricate SiNx waveguides with H content <20%, good uniformity and propagation losses of 1.5 dB cm-1 at 1550nm and <1 dB.cm-1 at 1310nm. As a result, this study can potentially help optimise the properties of the studied SiNx layers for different applications.
0022-3727
1-12
Domínguez Bucio, Thalía
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Khokhar, Ali Z.
2eedd1cc-8ac5-4f8e-be25-930bd3eae396
Lacava, Cosimo
a0a31a27-23ac-4a73-8bb4-2f02368fb8bd
Stanković, Stevan
13e8c464-b876-405a-b442-7c437a6eafd3
Mashanovich, Goran Z.
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Petropoulos, Periklis
522b02cc-9f3f-468e-bca5-e9f58cc9cad7
Gardes, Frederic Y.
7a49fc6d-dade-4099-b016-c60737cb5bb2
Domínguez Bucio, Thalía
83b57799-c566-473c-9b53-92e9c50b4287
Khokhar, Ali Z.
2eedd1cc-8ac5-4f8e-be25-930bd3eae396
Lacava, Cosimo
a0a31a27-23ac-4a73-8bb4-2f02368fb8bd
Stanković, Stevan
13e8c464-b876-405a-b442-7c437a6eafd3
Mashanovich, Goran Z.
c806e262-af80-4836-b96f-319425060051
Petropoulos, Periklis
522b02cc-9f3f-468e-bca5-e9f58cc9cad7
Gardes, Frederic Y.
7a49fc6d-dade-4099-b016-c60737cb5bb2

Domínguez Bucio, Thalía, Khokhar, Ali Z., Lacava, Cosimo, Stanković, Stevan, Mashanovich, Goran Z., Petropoulos, Periklis and Gardes, Frederic Y. (2016) Material and optical properties of low-temperature NH3-free PECVD SiNx layers for photonic applications. Journal of Physics D: Applied Physics, 50 (2), 1-12. (doi:10.1088/1361-6463/50/2/025106).

Record type: Article

Abstract

SiNx layers intended for photonic applications are typically fabricated using LPCVD and PECVD. These techniques rely on high-temperature processing (>400 °C) to obtain low propagation losses. An alternative version of PECVD SiNx layers deposited at temperatures below 400°C with a recipe that does not use ammonia (NH3-free PECVD) was previously demonstrated to be a good option to fabricate strip waveguides with propagation losses <3dB cm-1. We have conducted a systematic investigation of the influence of the deposition parameters on the material and optical properties of NH3-free PECVD SiNx layers fabricated at 350°C using a design of experiments methodology. In particular, this paper discusses the effect of the SiH4 flow, RF power, chamber pressure and substrate on the structure, uniformity, roughness, deposition rate, refractive index, chemical composition, bond structure and H content of NH3-free PECVD SiNx layers. The results show that the properties and the propagation losses of the studied SiNx layers depend entirely on their compositional N/Si ratio, which is in fact the only parameter that can be directly tuned using the deposition parameters along with the film uniformity and deposition rate. These observations provide the means to optimise the propagation losses of the layers for photonic applications through the deposition parameters. In fact, we have been able to fabricate SiNx waveguides with H content <20%, good uniformity and propagation losses of 1.5 dB cm-1 at 1550nm and <1 dB.cm-1 at 1310nm. As a result, this study can potentially help optimise the properties of the studied SiNx layers for different applications.

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Accepted/In Press date: 4 November 2016
e-pub ahead of print date: 1 December 2016
Published date: 1 December 2016
Organisations: Optoelectronics Research Centre

Identifiers

Local EPrints ID: 402364
URI: https://eprints.soton.ac.uk/id/eprint/402364
ISSN: 0022-3727
PURE UUID: 6921d0d7-ab28-49f7-8323-272aabd2b89a
ORCID for Thalía Domínguez Bucio: ORCID iD orcid.org/0000-0002-3664-1403
ORCID for Cosimo Lacava: ORCID iD orcid.org/0000-0002-9950-8642
ORCID for Stevan Stanković: ORCID iD orcid.org/0000-0001-6154-3138
ORCID for Periklis Petropoulos: ORCID iD orcid.org/0000-0002-1576-8034

Catalogue record

Date deposited: 29 Nov 2016 09:20
Last modified: 09 Dec 2019 19:23

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