The Impact of Substrate Bias on a Remote Plasma Sputter Coating Process for Conformal Coverage of Trenches and 3D Structures.

Brown, Hayley L., Thornley, Sarah A., Wakeham, Steve J., Thwaites, Mike J., Curry, Richard J. and Baker, Mark A (2015) The Impact of Substrate Bias on a Remote Plasma Sputter Coating Process for Conformal Coverage of Trenches and 3D Structures. Journal of Physics D: Applied Physics, 48 (33).

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Abstract

With the progression towards higher aspect ratios and finer topographical dimensions in many micro- and nano-systems, it is of technological importance to be able to conformally deposit thin films onto such structures. Sputtering techniques have been developed to provide such conformal coverage through a combination of coating re-sputtering and ionised physical vapour deposition (IPVD), the latter by use of a secondary plasma source or a pulsed high target power (HiPIMS). This paper reports on the use of an alternate remote plasma sputtering technique in which a high density (>1013 cm-3) magnetised plasma is used for sputter deposition, and additionally is shown to provide IPVD and a re-sputtering capability. From the substrate I-V characteristics and optical emission spectroscopy (OES) data, it is shown that remote plasma sputtering is an inherently continuous IPVD process (without the need of a secondary discharge). Through the reactive deposition of Al2O3 onto complex structures, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) results demonstrate that applying a negative substrate bias during film growth can result in re-sputtering of deposited material and film growth on surfaces obscured from the initial sputter flux. Using 5:1 (height:width) aspect ratio trenches, the substrate bias was set to 0, -245 and -334 V. At 0 V substrate bias, the alumina coating is predominantly deposited on the horizontal surfaces; at -344 V, it is predominantly deposited onto the side walls and at -245 V a more uniform layer thickness is obtained over the trench. The process was optimised further by alternating the substrate bias between -222 and -267 V, with a 50 % residence time at each voltage, yielding a more uniform conformal coverage of the 5:1 aspect ratio structures over large areas.

Item Type:	Article
Divisions :	Faculty of Engineering and Physical Sciences > Mechanical Engineering Sciences
Authors :	Name Email ORCID Brown, Hayley L. h.l.brown@surrey.ac.uk Thornley, Sarah A. sarah.thornley@plasmaquest.co.uk Wakeham, Steve J. steve.wakeham@plasmaquest.co.uk Thwaites, Mike J. mike.thwaites@plasmaquest.co.uk Curry, Richard J. r.curry@surrey.ac.uk Baker, Mark A m.baker@surrey.ac.uk
Date :	2015
Funders :	EPSRC
DOI :	JPhysD-105037
Additional Information :	Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
Depositing User :	Hayley Brown
Date Deposited :	28 Jul 2015 08:24
Last Modified :	16 Jan 2019 16:57
URI:	http://epubs.surrey.ac.uk/id/eprint/807891

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