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. 2018 Mar 30;11(4):530.
doi: 10.3390/ma11040530.

Ridge Minimization of Ablated Morphologies on ITO Thin Films Using Squared Quasi-Flat Top Beam

Hoon-Young Kim  1   2 , Jin-Woo Jeon  3 , Wonsuk Choi  4   5 , Young-Gwan Shin  6   7 , Suk-Young Ji  8   9 , Sung-Hak Cho  10   11
Affiliations

Ridge Minimization of Ablated Morphologies on ITO Thin Films Using Squared Quasi-Flat Top Beam

Hoon-Young Kim et al. Materials (Basel). .

Abstract

In this study, we explore the improvements in pattern quality that was obtained with a femtosecond laser with quasi-flat top beam profiles at the ablated edge of indium tin oxide (ITO) thin films for the patterning of optoelectronic devices. To ablate the ITO thin films, a femtosecond laser is used that has a wavelength and pulse duration of 1030 nm and 190 fs, respectively. The squared quasi-flat top beam is obtained from a circular Gaussian beam using slits with varying x-y axes. Then, the patterned ITO thin films are measured using both scanning electron and atomic force microscopes. In the case of the Gaussian beam, the ridge height and width are approximately 39 nm and 1.1 μm, respectively, whereas, when the quasi-flat top beam is used, the ridge height and width are approximately 7 nm and 0.25 μm, respectively.

Keywords: ITO thin film; ablation; femtosecond laser; ridge minimization; slit.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Figure 1
Figure 1
Schematic of the femtosecond laser patterning system.
Figure 2
Figure 2
(a) Scanning electron microscope (SEM) image of ablation with the Gaussian beam profile; (b) Enlarged SEM image of the ablated edge with Gaussian beam irradiation; (c) SEM image of ablation with the quasi-flat top beam profile; and (d) Enlarged SEM image of the ablated edge with quasi-flat top beam irradiation.
Figure 3
Figure 3
SEM images; Parts (a) and (b) are the 5× enlarged versions of Figure 2b,d, respectively.
Figure 4
Figure 4
SEM images (a) with Gaussian beam irradiation and (b) with the quasi-flat top beam, measured by tilting the pattern.
Figure 5
Figure 5
Images of the atomic force microscope (AFM) two-dimensional (2D) morphology data (a) with the Gaussian beam profile, and (c) with the quasi-flat top beam profile. The cross-section of the ablated area obtained by AFM after femtosecond laser irradiation (b) with the Gaussian beam (d) with the quasi-flat top beam.
Figure 5
Figure 5
Images of the atomic force microscope (AFM) two-dimensional (2D) morphology data (a) with the Gaussian beam profile, and (c) with the quasi-flat top beam profile. The cross-section of the ablated area obtained by AFM after femtosecond laser irradiation (b) with the Gaussian beam (d) with the quasi-flat top beam.
Figure 6
Figure 6
Images of the enlarged AFM three-dimensional (3D) morphology (a) with Gaussian beam irradiation, and (c) with quasi-flat top beam irradiation. The cross-sectional graph of the ablation edge obtained from the enlarged AFM image (b) with Gaussian beam irradiation, and (d) with quasi-flat top beam irradiation.
Figure 7
Figure 7
Three-dimensional morphology image (a) and cross-sectional graph obtained at the ablation edge using the AFM after one pulse irradiation (b).
See this image and copyright information in PMC

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