Sono-electrodeposition transfer of micro-scale copper patterns on to A7 substrates using a mask-less method

Abstract

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Design of an ultrasonic tank reactor for copper deposition at electrodes separated by a narrow gap

“…Possibly, lower US power, where resist delamination does not occur, could be an alternative. This has been examined in a separate study by our group, Serra et al, [29]. Interestingly, the work by the authors in the present paper (Coleman and Roy) has shown that it is possible to use ultrasonic agitation within the narrow gap between two plates using an ultrasonic tank reactor, even when the plates are size A7.…”

“…Ultrasonic (US) agitation has been shown to improve stirring in electrochemical systems [19][20][21] due to cavitation phenomena [22][23][24]. Therefore, the authors of this paper carried out experiments to determine if US agitation could be used to provide stirring for metallisation using Enface technique [15,[25][26][27][28][29]]. An initial assessment using an US probe placed within a 500 mL 'beaker-type' system was shown to improve mass transfer by ten-fold during copper deposition within an electrode gap of 1500 μm [25].…”

Ultrasonic Agitation for Emerging Electrodeposition Systems

“…Specifically the two systems correspond to laboratory scale measurement and industrial scale apparatus. By constrained space we have limited ourselves to a narrow gap between two electrodes; this is generally in the mm scale [23].…”

“…29,30 Here we explain the approach taken by the authors to address an important question: Can US be employed to increase material transport within constrained spaces, i.e., a narrow gap? 16,23 At this point, it is unclear to what extent agitation could be improved; furthermore, it was not even evident if experimental techniques, such as the limiting current method, could be applied in these circumstances. In fact, other researchers had already found that there are distortions in potential distribution due to the presence of an US probe.…”

“…34 In addition, much of the earlier work has focused on high power to influence reaction chemistry, and studies related to microfabrication have shown that lower power may be more useful for electrodeposition. 23,24 Figure 5 shows the design for the electrodes with a narrow gap within a tank system. The electrodes are placed at the center of the tank, and connectors to the electrodes as well as the inter-electrode gap are maintained via the design of an appropriate holder which is described in detail elsewhere.…”