TY - JOUR
T1 - Reverse-Offset Printing of Polymer Resist Ink for Micrometer-Level Patterning of Metal and Metal-Oxide Layers
AU - Sneck, Asko
AU - Ailas, Henri
AU - Gao, Feng
AU - Leppäniemi, Jaakko
N1 - Funding Information:
The work was funded in part by the Academy of Finland under grant agreement no. 328627 (project FLEXRAD). We thank the following colleagues at VTT: Dr. T. Mäkelä and M. Kainlauri for the SiO evaporation and ITO sputtering and analysis, respectively, Dr. T. Haatainen for FIB etching and SEM analysis, J. Hiitola-Keinänen, Dr. A. Alastalo, and Dr. T. Mäkelä for discussions, and P. Hakkarainen for the general technical assistance. Nanolab Technologies Inc. is acknowledged for the TEM, STEM, and EELS analyses.
Publisher Copyright:
© 2021 The Authors. Published by American Chemical Society.
PY - 2021/9/8
Y1 - 2021/9/8
N2 - 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.
AB - 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.
KW - high-resolution printing
KW - metal mesh electrode
KW - metal patterning
KW - reverse-offset printing
KW - thin-film transistor
KW - transparent conductor
UR - http://www.scopus.com/inward/record.url?scp=85114649534&partnerID=8YFLogxK
U2 - 10.1021/acsami.1c08126
DO - 10.1021/acsami.1c08126
M3 - Article
C2 - 34432413
AN - SCOPUS:85114649534
SN - 1944-8244
VL - 13
SP - 41782
EP - 41790
JO - ACS Applied Materials & Interfaces
JF - ACS Applied Materials & Interfaces
IS - 35
ER -
