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Micromanufacturing in Fused Silica via Femtosecond Laser Irradiation Followed by Gas-Phase Chemical Etching
Politecnico di Milano Dipartimento di Chimica, Materiali e Ingegneria Chimica ”Giulio Natta”, Via Luigi Mancinelli, 7, 20133 Milan, Italy
Politecnico di Milano Istituto di Fotonica e Nanotecnologie-CNR, Dipartimento di Fisica, Piazza Leonardo da Vinci, 32, 20133 Milan, Italy
Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali, Via G. Giusti, 9, 50121 Firenze, Italy
* Author to whom correspondence should be addressed.
Received: 6 August 2012; in revised form: 28 August 2012 / Accepted: 17 September 2012 / Published: 28 September 2012
Abstract: Femtosecond laser irradiation followed by chemical etching (FLICE) with hydrogen fluoride (HF) is an emerging technique for the fabrication of directly buried, three-dimensional microfluidic channels in silica. The procedure, as described in literature, consists of irradiating a silica slab followed by chemical etching using hydrogen fluoride. With aqueous HF the etching process is diffusion-limited and is self-terminating, leading to maximum microchannel lengths of about 1.5 mm, while the use of low-pressure gaseous HF etchant can quickly produce 3 mm long channels with an aspect ratio (Length/Diameter) higher than 25. By utilizing this methodology the aspect ratio is not constant, but depends on the length of the channel. When the microchannel is short the aspect ratio increases quickly until it reaches a maximum length at around 1400 µm. Thereafter the aspect ratio starts to decrease slowly. In this paper we present a variation of the low-pressure gaseous HF etching method, which is based on the dynamic displacement of the etchant. This method results in a 13% increase in the aspect ratio (L/D = 29) at the expense of a low etching speed (4 µm/min).
Keywords: laser micromachining; FLICE; silicon dioxide; selective etching; anhydrous hydrogen fluoride
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MDPI and ACS Style
Venturini, F.; Sansotera, M.; Vazquez, R.M.; Osellame, R.; Cerullo, G.; Navarrini, W. Micromanufacturing in Fused Silica via Femtosecond Laser Irradiation Followed by Gas-Phase Chemical Etching. Micromachines 2012, 3, 604-614.
Venturini F, Sansotera M, Vazquez RM, Osellame R, Cerullo G, Navarrini W. Micromanufacturing in Fused Silica via Femtosecond Laser Irradiation Followed by Gas-Phase Chemical Etching. Micromachines. 2012; 3(4):604-614.
Venturini, Francesco; Sansotera, Maurizio; Vazquez, Rebeca Martinez; Osellame, Roberto; Cerullo, Giulio; Navarrini, Walter. 2012. "Micromanufacturing in Fused Silica via Femtosecond Laser Irradiation Followed by Gas-Phase Chemical Etching." Micromachines 3, no. 4: 604-614.