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