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Electroless Au Plating of CMOS Microelectrodes: Fabrication, Characterisation and Electrochemical Me

IEEE Sensors Letters | Li, M; Naeem, A; Lancashire, H; Vanhoestenberghe, A; Ghoreishizadeh, S (2024) | An essential step in developing amperometric sensors directly on CMOS integrated circuits (IC...

22 May 2024

Electroless Au Plating of CMOS Microelectrodes: Fabrication, Characterisation and Electrochemical Measurement

Abstract

An essential step in developing amperometric sensors directly on CMOS integrated circuits (ICs) is to cover the exposed uppermost metal layer (aluminium pads) with a thin layer of noble metal to form the basis of the sensing electrode. A simple and scalable method to achieve the gold layer is through electroless plating. Despite the popularity of electroless plating in e.g. PCB manufacturing, there is a lack of information on how it can be applied to Al microelectrodes, and what the electrochemical performances of Au-coated microelectrodes are. This paper presents a detailed process for electroless gold plating of CMOS microelectrodes, with a step-by-step characterisation of the surface roughness, thickness, and elemental composition to optimise the deposition parameters (e.g. deposition time and temperature) for achieving a smooth and uniform gold coverage of the microelectrodes. A gold layer with a rms surface roughness of 53.6 ± 7.9 nm is achieved on the microelectrodes and successfully characterised by cyclic voltammetry in a ferri/ferrocyanide solution. Sonication, oxygen plasma, and continuous cyclic voltammetry are applied to the Au-coated microelectrodes to determine their mechanical and electrochemical stability.

Publication Type:Journal Article
Publication Sub Type:Article
Authors:Li, M; Naeem, A; Lancashire, H; Vanhoestenberghe, A; Ghoreishizadeh, S
Publisher:Institute of Electrical and Electronics Engineers (IEEE)
Publication date:22/05/2024
Pagination:4501404
Journal:IEEE Sensors Letters
Volume:8
Status:Published
Print ISSN:2475-1472
DOI:10.1109/LSENS.2024.3404153

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