Micromanufacturing in Fused Silica via Femtosecond Laser Irradiation Followed by Gas-Phase Chemical Etching

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). OPEN ACCESSMicromachines 2012, 3 605

Solid-state reduction of silica nanoparticles via oxygen abstraction from SiO4 units by polyolefins under mechanical stressing

“…Researchers in the eld of semiconductor etching report that uorine is a powerful disrupter of silica-based compounds. [49][50][51] While the related process is conventionally practiced in liquid 52 or vapor 53 phases, same principles could be applicable in the solid phase. Decrease in the O1s binding energy is closely correlated with decreasing interaction parameter of cation and anion of many metal oxides, 54 which, in turn, parallels to the polarizability.…”

Maskless, fast and highly selective etching of fused silica with gaseous fluorine and gaseous hydrogen fluoride

“…A scheme of the experimental setup used for the gaseous etching is shown in figure 2. It derives from a similar apparatus that we developed in a previous study [15,16,23]. The setup was built using fluorine resistant alloys with 1/4 in.…”

“…With this technique, it is possible to produce three-dimensional microchannels, chambers and complex structures inside fused silica substrates. The procedure described in the literature consists in a focused laser irradiation of the silica slab followed by chemical etching using hydrofluoric acid (HF), either in the aqueous [12][13][14] or gas phase [15,16]. The photomodification is executed by irradiating the transparent material placed on a motorized translation stage by a train of pulses of a focused femtosecond laser beam.…”

“…To overcome these limitations, we have recently introduced a gaseous HF implementation of the FLICE technique obtaining an aspect ratio higher than 30 [16] and a self-terminating length in excess of 3 mm [15].…”

Tailored surface birefringence by femtosecond laser assisted wet etching

“…Generally, the etching is performed with diluted hydrofluoric acid (HF), which was successfully applied in fabrication of micro-channels, and tunnels [3,[9][10][11][12][13][14][15] or more complex structures [8,[16][17][18][19].…”