Laser-Induced Backside Wet Etching of Transparent Materials with Organic and Metallic Absorbers

Abstract

Recommended by Jacques AlbertLaser-induced backside wet etching (LIBWE) allows the high-quality etching of transparent materials for micro-and nanopatterning. Recent own results of LIBWE with hydrocarbon and metallic absorbers (H-and M-LIBWE) are summarized and compared with selected results of other groups regarding the etching process and the etched surface. Significant results on the impact of the liquid absorber, the material and the wavelength, and the pulse length of the laser to the etching are selected for this comparison. The etching of submicron-sized periodic structures in sapphire and fused silica with interference techniques and the selection of the preferred method in dependence on the material and the processing goal discussed. The experimental results are discussed on a thermal model considering both interface and volume absorption of the laser beam. These results have the conclusion that the etching at M-LIBWE is mainly due to material melting and evaporation whereas at H-LIBWE, a modified near-surface region with a very high absorption is ablated.

Hybrid laser precision engineering of transparent hard materials: challenges, solutions and applications

“…For practical applications, it is important to precisely control the etching rate and surface quality. A large number of factors and parameters are involved in the LIBWE process including liquid properties, solution concentration, scanning speed, and laser fluence 94 . Careful optimization of processing parameters leads to the precision laser engineering of transparent hard materials toward a high etching rate and high surface quality.…”

“…LIBWE offers an alternative method to fabricate microstructures/patterns on transparent materials with a singlestep process. Defined line-and-space, microfluidic channel, grid and grating structures/patterns by LIBWE have already been demonstrated 75,81,90,94,96,99,100 . The profiles of the fabricated structures show sharp edges and smooth surfaces without debris and micro-cracks.…”

Laser Micromachining of Glass, Silicon, and Ceramics

“…They reported a well-defined micropattern formation without debris and microcrack around the etched area. Zimmer and Böhme, 2008, suggested hydrocarbon and metallic absorbers for LIBWE of transparent materials [14,15].…”

Femtosecond Beam Transformation Effects in Water, Enabling Increased Throughput Micromachining in Transparent Materials

“…Therefore, it is necessary to increase the efficiency (ablated material/unit energy/unit of time) of the micromachining process as much as possible to fulfil the necessary requirements. Several techniques exist for processing materials with femtosecond pulses which include: direct ablation in air [14,15], back side wet etching [16][17][18], spatiotemporally enhanced focusing [19,20], laser-assisted etching (LAE) [21][22][23][24][25][26], and gas-assisted processing [27][28][29]. Although the techniques presented above all have their advantages and disadvantages, when talking about cutting/drilling deep (> 500 µm) structures inside the material, all of the stated techniques fall short (with the exception of LAE), and ultimately fall victim to slow processing and heat-affected zones around the cut.…”