Reverse-Offset Printing of Polymer Resist Ink for Micrometer-Level Patterning of Metal and Metal-Oxide Layers

Asko Sneck, Henri Ailas, Feng Gao, Jaakko Leppäniemi (Corresponding Author)

Research output: Contribution to journalArticleScientificpeer-review

Abstract

Printed electronics has advanced during the recent decades in applications such as organic photovoltaic cells and biosensors. However, the main limiting factors preventing the more widespread use of printing in flexible electronics manufacturing are (i) the poor attainable linewidths via conventional printing methods (≫10 μm), (ii) the limited availability of printable materials (e.g., low work function metals), and (iii) the inferior performance of many printed materials when compared to vacuum-processed materials (e.g., printed vs sputtered ITO). Here, we report a printing-based, low-temperature, low-cost, and scalable patterning method that can be used to fabricate high-resolution, high-performance patterned layers with linewidths down to ∼1 μm from various materials. The method is based on sequential steps of reverse-offset printing (ROP) of a sacrificial polymer resist, vacuum deposition, and lift-off. The sharp vertical sidewalls of the ROP resist layer allow the patterning of evaporated metals (Al) and dielectrics (SiO) as well as sputtered conductive oxides (ITO), where the list is expandable also to other vacuum-deposited materials. The resulting patterned layers have sharp sidewalls, low line-edge roughness, and uniform thickness and are free from imperfections such as edge ears occurring with other printed lift-off methods. The applicability of the method is demonstrated with highly conductive Al (∼5 × 10-8 ωm resistivity) utilized as transparent metal mesh conductors with ∼35 ω□ at 85% transparent area percentage and source/drain electrodes for solution-processed metal-oxide (In2O3) thin-film transistors with ∼1 cm2/(Vs) mobility. Moreover, the method is expected to be compatible with other printing methods and applicable in other flexible electronics applications, such as biosensors, resistive random access memories, touch screens, displays, photonics, and metamaterials, where the selection of current printable materials falls short.

Original languageEnglish
Pages (from-to)41782-41790
Number of pages9
JournalACS Applied Materials and Interfaces
Volume13
Issue number35
DOIs
Publication statusPublished - 8 Sep 2021
MoE publication typeA1 Journal article-refereed

Keywords

  • high-resolution printing
  • metal mesh electrode
  • metal patterning
  • reverse-offset printing
  • thin-film transistor
  • transparent conductor

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