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G. A. C. M. Spierings

Bio: G. A. C. M. Spierings is an academic researcher from Philips. The author has contributed to research in topics: Dissolution & Borosilicate glass. The author has an hindex of 5, co-authored 8 publications receiving 430 citations.

Papers
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Journal ArticleDOI
G. A. C. M. Spierings1
TL;DR: The etch rate is determined by the composition of the etchant as well as by the glass, although the mechanism of dissolution is not influenced as discussed by the authors, since the dissolution reaction is governed by the adsorption of the two reactive species: HF and HF 2 - and the catalytic action of H+ ions.
Abstract: The etching of silicate glasses in aqueous hydrofluoric acid solutions is applied in many technological fields. In this review most of the aspects of the wet chemical etching process of silicate glasses are discussed. The mechanism of the dissolution reaction is governed by the adsorption of the two reactive species: HF and HF 2 - and the catalytic action of H+ ions, resulting in the breakage of the siloxane bonds in the silicate network. The etch rate is determined by the composition of the etchant as well as by the glass, although the mechanism of dissolution is not influenced. In the second part of this review, diverse applications of etching glass objects in technology are described. Etching of SiO2 and doped SiO2 thin films, studied extensively for integrated circuit technology, is discussed separately.

371 citations

Journal ArticleDOI
TL;DR: In this article, the dissolution rate of a multicomponent (Na2O-MgO-CaO-SiO2) silicate glass in aqueous HF solutions is studied.
Abstract: The dissolution (or etching) of a multicomponent (Na2O-MgO-CaO-SiO2) silicate glass in aqueous HF solutions is studied. The solutions were chosen in the systems HF-HNO3-H2O, HF-HCl-H2O and HF-H2SO4-H2O, and the temperatures varied from 25 to 60° C. SEM micrographs of the glass surface after etching show an “orange peel” surface structure which develops during etching and which originates from surface flaws. The dissolution rate of the glass was found to increase with higher HF concentration, higher strong-acid concentrations and higher temperatures. The dissolution rate is determined by the reaction of HF molecules and HF2 ions with the Si-O-Si grouping surrounding the SiO4 tetrahedron. In the multicomponent glass some of these bonds are non-bridging due to the presence of Na2O, CaO and MgO, increasing the dissolution rate significantly. H+ ions introduced by adding strong acids to the etch solution adsorb on the surface and catalyse the dissolution reaction. Several models used to describe the relation between the dissolution rate and the H+ concentration are discussed.

39 citations

Journal ArticleDOI
G. A. C. M. Spierings1
TL;DR: In this article, the dissolution rate of multicomponent silicate glasses in a 2.9m aqueous HF solution is investigated as a function of its composition. But no linear relations are observed between the composition of the glass and its dissolution rate.
Abstract: The dissolution rate of multicomponent silicate glasses in a 2.9m aqueous HF solution is investigated as a function of its composition. The glasses studied are composed of SiO2, B2O3, Al2O3, CaO, MgO, ZnO, Na2O and K2O, covering the compositions of most of the technologically important glasses. Unlike many physical properties, no linear relations are observed between the composition of the glass and its dissolution rate. The dissolution rate of a multicomponent silicate glass is found to be largely determined by two factors: The degree of linkage or connectivity of the silicate network and the concentration of SiO2 in the glass. It is proposed that the dissolution of the glasses is preceded by the leaching of alkali and alkaline earth components present in the glass, followed by the subsequent dissolution of the leached layer. Probably fluorine species will diffuse into the leached layer to enhance the dissolution rate. Analysis of the activation energy data indicates that in some corrosive glasses the leaching itself becomes rate determining.

38 citations

Journal ArticleDOI
TL;DR: Refractive index and density data of glasses having molar compositions 15% A2O-10% CaO-45% SiO2-(30−x%) GeO2-x% B2O3 with A=Na or K are reported in this paper.
Abstract: Refractive index and density data of glasses having molar compositions 15% A2O-10% CaO-45% SiO2-(30−x%) GeO2-x% B2O3 with A=Na or K are reported. From these data the molar refraction and the contribution of oxygen to the molar refraction are calculated. The co-ordination of germanium and boron in these glasses is discussed. At x=0, GeO6 octahedra are observed which are gradually transformed into GeO4 tetra-hedra as the GeO2 is replaced by B2O3. In B2O3-rich glasses no GeO6 octahedra are present and the structure of the B2O3-rich glasses is found to be the same as that of comparable alkali borosilicate glasses.

5 citations


Cited by
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Journal ArticleDOI
G. A. C. M. Spierings1
TL;DR: The etch rate is determined by the composition of the etchant as well as by the glass, although the mechanism of dissolution is not influenced as discussed by the authors, since the dissolution reaction is governed by the adsorption of the two reactive species: HF and HF 2 - and the catalytic action of H+ ions.
Abstract: The etching of silicate glasses in aqueous hydrofluoric acid solutions is applied in many technological fields. In this review most of the aspects of the wet chemical etching process of silicate glasses are discussed. The mechanism of the dissolution reaction is governed by the adsorption of the two reactive species: HF and HF 2 - and the catalytic action of H+ ions, resulting in the breakage of the siloxane bonds in the silicate network. The etch rate is determined by the composition of the etchant as well as by the glass, although the mechanism of dissolution is not influenced. In the second part of this review, diverse applications of etching glass objects in technology are described. Etching of SiO2 and doped SiO2 thin films, studied extensively for integrated circuit technology, is discussed separately.

371 citations

Journal ArticleDOI
TL;DR: In this paper, the combination of femtosecond laser dielectric modification and selective chemical etching was used to fabricate high-quality microchannels in glass, and the optimum irradiation conditions needed to produce high-aspect ratio micro-channels with small symmetric cross-sections and smooth walls.
Abstract: We use the combination of femtosecond laser dielectric modification and selective chemical etching to fabricate high-quality microchannels in glass. The photoinduced modification morphology has been studied in fused silica and in borosilicate glass BK7, using ultra-high spatial resolution techniques of selective chemical etching followed by atomic force or scanning electron microscopy. The analysis shows that the high differential etch rate inside the modified regions, is determined by the presence of polarization-dependent self-ordered periodic nanocracks or nanoporous structures. We also investigate the optimum irradiation conditions needed to produce high-aspect ratio microchannels with small symmetric cross-sections and smooth walls.

275 citations

Journal ArticleDOI
TL;DR: In this article, a microfluidic channel with a depth of 35.95±0.39 µm is formed after 40 min buffered oxide etching in an ultrasonic bath.
Abstract: This paper describes a fast, low-cost but reliable process for the fabrication of microfluidic systems on soda-lime glass substrates. Instead of using an expensive metal or polisilicon/nitride layer as an etch mask, a thin layer of AZ 4620 positive photoresist (PR) is used for buffered oxide etching (BOE) of soda-lime glass. A novel two-step baking process prolongs the survival time of the PR mask in the etchant, which avoids serious peeling problems of the PR. A new process to remove precipitated particles generated during the etching process is also reported in which the glass substrate is dipped into a 1 M hydrochloride solution. A microfluidic channel with a depth of 35.95±0.39 µm is formed after 40 min BOE in an ultrasonic bath. The resulting channel has a smooth profile with a surface roughness of less than 45.95±7.96 A. Glass chips with microfluidic channels are then bonded at 580 °C for 20 min to seal the channel while a slight pressure is applied. A new bonding process has been developed such that the whole process can be finished within 10 h. To our knowledge, this is the shortest processing time that has ever been reported. In the present study, an innovative microfluidic device, a `micro flow-through sampling chip', has been demonstrated using the fabrication method. Successful sampling and separation of Cy5-labelled bovine serum albumin (BSA) and anti-BSA has been achieved. This simple fabrication process is suitable for fast prototyping and mass production of microfluidic systems.

255 citations

Journal ArticleDOI
TL;DR: The effect of various HF-based etching processes on the laser damage resistance of scratched fused silica surfaces has been investigated in this article, where the etch process was optimized to remove or prevent the presence of identified precursors (chemical impurities, fracture surfaces, and silica-based redeposit) known to lead to laser damage initiation.
Abstract: The effect of various HF-based etching processes on the laser damage resistance of scratched fused silica surfaces has been investigated. Conventionally polished and subsequently scratched fused silica plates were treated by submerging in various HF-based etchants (HF or NH4F:HF at various ratios and concentrations) under different process conditions (e.g., agitation frequencies, etch times, rinse conditions, and environmental cleanliness). Subsequently, the laser damage resistance (at 351 or 355 nm) of the treated surface was measured. The laser damage resistance was found to be strongly process dependent and scaled inversely with scratch width. The etching process was optimized to remove or prevent the presence of identified precursors (chemical impurities, fracture surfaces, and silica-based redeposit) known to lead to laser damage initiation. The redeposit precursor was reduced (and hence the damage threshold was increased) by: (1) increasing the SiF62− solubility through reduction in the NH4F concentration and impurity cation impurities, and (2) improving the mass transport of reaction product (SiF62−) (using high-frequency ultrasonic agitation and excessive spray rinsing) away from the etched surface. A 2D finite element crack-etching and rinsing mass transport model (incorporating diffusion and advection) was used to predict reaction product concentration. The predictions are consistent with the experimentally observed process trends. The laser damage thresholds also increased with etched amount (up to ∼30 μm), which has been attributed to: (1) etching through lateral cracks where there is poor acid penetration, and (2) increasing the crack opening resulting in increased mass transport rates. With the optimized etch process, laser damage resistance increased dramatically; the average threshold fluence for damage initiation for 30 μm wide scratches increased from 7 to 41 J/cm2, and the statistical probability of damage initiation at 12 J/cm2 of an ensemble of scratches decreased from ∼100 mm−1 of scratch length to ∼0.001 mm−1.

252 citations

Journal ArticleDOI
D. Martin Knotter1
TL;DR: In this article, a reaction mechanism for the dissolution process of silicon dioxide networks in aqueous HF-based solutions is proposed, which is the substitution of a surface SiOH group which is bonded to three bridging oxygen atoms.
Abstract: A reaction mechanism is proposed for the dissolution process of silicon dioxide networks in aqueous HF-based solutions. Etch experiments with thermally grown silicon dioxide were used to create a model for the etch process. Literature data on the etching of other vitreous silicon dioxide materials were used to refine the model. A new method, using a quartz microbalance, is used to monitor the etch rate in situ and to establish the reactive species. The first reaction step determines the rate of the etch process. It is the substitution of a surface SiOH group, which is bonded to three bridging oxygen atoms, by an SiF group. Due to an acid/base equilibrium reaction of the silanol groups on the surface with its protonated and deprotonated forms, the substitution reaction rate is pH dependent. At low pH ( 1.5), the elimination of...

247 citations