New plasma patterning of AG nanowire using high pressure micro-discharge

In order to apply the atmospheric pressure plasmas to etching process of metal thin films on the flexible substrates such as the pattering of silver nanowire(AgNW) materials on the polyethylene terephthalate (PET) substrate, it is very important to increase the role of charge particles, ions rather than radicals. In this sense, first only Ar gas excluding the electronegative gases, O₂ and N₂ in the air should participate in producing intense plasma for metal thin film process¹. Second, to obtain high electric field intensity for maximizing the ion energy during the discharge, the high voltage with fast rising slope should be applied to the planar electrodes with very small gap. In this study, pure Ar plasma was produced in the microdischarge channel using the DC pulsed power source, and succeeded in etching the AgNW materials on the PET substrate under atmospheric pressure. To form the microdischarge space necessary for the Ag etching area with a 20mm length and 20 um width, the following process was carried out; i) SU8 mold on silicon substrate with specific embossed carving was fabricated for patterned line using the photolithography, ii) by pouring the polydimethylsiloxane (PDMS) on this SU8 mold and inserting the powered electrode inside the PDMS, the PDMS frame was fabricated, and iii) finally, a micro-discharge space was formed by reversible bonding between the PDMS frame and PET substrate on the counter electrode. In this experiment, the rectangular voltage waveforms with various duty ratios, voltage levels, and frequencies were used to examine the proper etching condition of AgNWs on the PET substrates. The optical emission measurements and SEM images confirm that pure intense Ar plasma contributed to effectively etching the AgNW on the PET substrate with minimalized thermal damages.