Influence of near-edge Laser-Induced Periodic Surface Structures (LIPSS) on the electrical properties of fs-laser-machined ITO microcircuits

Frechilla, A. (Universidad de Zaragoza) ; Martínez, E. ; Moral, J. del ; López-Santos, C. ; Frechilla, J. (Universidad de Zaragoza) ; Nuñez-Gálvez, F. ; López-Flores, V. ; de la Fuente, G.F. ; Hülagü, D. ; Bonse, J. ; González-Elipe, A.R. ; Borrás, A. ; Angurel, L.A. (Universidad de Zaragoza)

Resumen: Scalable, cost-effective methods for processing transparent electrodes at the microscale are pivotal to advancing in electrochemistry, optoelectronics, microfluidics, and energy harvesting. In these fields, the precise fabrication of micrometric circuits and patterns plays a critical role in determining device performance, material compatibility, and integration with added-value substrates. In this context, Laser Subtractive Manufacturing stands out as a suitable microfabrication technique for its adaptability to diverse materials and complex configurations, as well as its straightforward scalability, affordability, and eco-friendly nature. However, a challenge in micromachining metals and metal oxides is the inherent formation of Laser-Induced Periodic Surface Structures (LIPSS), which
can significantly impair electrical conductivity, particularly when circuit dimensions fall within the micrometer range. Herein, we investigate the micromachining of electrical microcircuits using ultrashort pulse laser systems applied to transparent indium tin oxide (ITO) thin films. We analyze the formation of LIPSS at the edges of the micromachined regions associated with the Gaussian distribution of the energy within the laser spot, and the impact of these structures on the electrical properties of the circuits. Thus, we systematically evaluate the influence of LIPSS orientation and periodicity by fabricating various circuit patterns using femtosecond lasers at green (515 nm) and ultraviolet (UV) (343 nm) wavelengths. A correlation between electrical resistivity measurements and microstructure analysis, as determined by field emission scanning electron and transmission electron microscopy, reveals distinct effects of the formed nanostructures depending on the laser source and its polarization. For the green wavelength, the edge side regions where LIPSS are oriented perpendicular to the ITO track exhibit a resistance higher by a factor just above two compared to those where LIPSS are parallel. Additionally, UV laser processing results in a pronounced reduction of ITO thickness at the boundary between the LIPSS region and the substrate. The mechanisms for the formation of LIPSS with both wavelengths are also discussed. Furthermore, we have determined that in narrow conductive tracks with a width ranging from 6 to 8 µm, the impact of LIPSS is particularly significant because the LIPSS structured region occupies a dominant fraction of the total width.

Idioma: Inglés

DOI: 10.1016/j.apsusc.2026.166415

Año: 2026

Publicado en: Applied Surface Science 731 (2026), 166415 [13 pp.]
ISSN: 0169-4332

Financiación: info:eu-repo/grantAgreement/EUR/AEI/TED2021-130916B-I0
Financiación: info:eu-repo/grantAgreement/ES/DGA/T54-23R
Financiación: info:eu-repo/grantAgreement/ES/MCIU/PID2023-146041OB-C21
Financiación: info:eu-repo/grantAgreement/ES/MICINN/AEI/PID2020-113034RB-I00

Tipo y forma: Article (Published version)

Área (Departamento): Área Ing. Procesos Fabricación (Dpto. Ingeniería Diseño Fabri.)
Área (Departamento): Área Cienc.Mater. Ingen.Metal. (Dpto. Ciencia Tecnol.Mater.Fl.)