Micro-Hole Generation by High-Energy Pulsed Bessel Beams in Different Transparent Materials.

Valeria V Belloni,Paolo Di Trapani,Monica Bollani,Shane M Eaton,Ottavia Jedrkiewicz

doi:10.3390/mi12040455

Abstract

Micro-drilling transparent dielectric materials by using non-diffracting beams impinging orthogonally to the sample can be performed without scanning the beam position along the sample thickness. In this work, the laser micromachining process, based on the combination of picosecond pulsed Bessel beams with the trepanning technique, is applied to different transparent materials. We show the possibility to create through-apertures with diameter on the order of tens of micrometers, on dielectric samples with different thermal and mechanical characteristics as well as different thicknesses ranging from two hundred to five hundred micrometers. Advantages and drawbacks of the application of this technique to different materials such as glass, polymer, or diamond are highlighted by analyzing the features, the morphology, and the aspect-ratio of the through-holes generated. Alternative Bessel beam drilling configurations, and the possibility of optimization of the quality of the aperture at the output sample/air interface is also discussed in the case of glass.

Highlights

Micro-hole drilling of transparent materials plays an important role in the field of micromechanics, microelectronics, microbiology, and microphotonics [1]
The laser micromachining of the various transparent materials has been performed by using the two beam geometries described in the previous section, depending on the thickness of the sample to drill
We applied the Bessel beam hole drilling to inside different we do not observe thehave presence of damage due to shock waves ortechnique explosions the dielectric materials with different optical and mechanical properties and different thicknesses ranging from 200 μm to 500 μm

Summary

Introduction

Micro-hole drilling of transparent materials plays an important role in the field of micromechanics, microelectronics, microbiology, and microphotonics [1]. Photolithography is often applied to facilitate micro-drilling, but it requires advanced facilities and a high number of processing steps, and is limited in material type and geometry. Lasers are widely applied in scientific and industrial applications, offering highly directional and localized radiation facilitating material modifications at precise locations [2]. Ultrafast pulsed laser systems are especially important for the growing industrial demand for fast processing and for micrometer scale high-quality devices [3], overcoming the limitations due to the production of cracks or low fabrication rates of conventional methods such as diamond drilling, water jet drilling and micro-sand blasting [4]. The laser beam shape and the beam propagation features play a crucial role in determining the hole quality, and research continues to be carried out for the optimization of the system performance such as speed, throughput, sidewall taper, or symmetry [6,7,8]

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