Thin Film Ag Masking for Deep Glass Micromachining

Lee, Hing Wah; Bien, Daniel C. S.; Badaruddin, Siti Aishah Mohamad; Teh, Aun Shih

doi:10.1149/1.3483163

Cited by 4 publications

(2 citation statements)

References 22 publications

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“…If the masking layer presents a hydrophilic surface, the etching solution will easily penetrate through this crack and generate a pinhole. Many masking materials for wet etching of glass have been reported in the literature, including photoresist, 52 amorphous Si deposited at low (200 C) 53 or high temperatures (570 C), 54 LPCVD polysilicon, 55,56 Cr/Au, 57 Cr/photoresist, 58 bulk Si, 59 amorphous SiC/ PECVD, 60 Ag, 61 Mo, 62 and Ti. 63 A detailed analysis of masking materials used in wet etching of glass is presented in Ref.…”

Section: Wet Etchingmentioning

confidence: 99%

A practical guide for the fabrication of microfluidic devices using glass and silicon

Iliescu¹,

Taylor²,

Avram³

et al. 2012

Biomicrofluidics

310

207

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This paper describes the main protocols that are used for fabricating microfluidic devices from glass and silicon. Methods for micropatterning glass and silicon are surveyed, and their limitations are discussed. Bonding methods that can be used for joining these materials are summarized and key process parameters are indicated. The paper also outlines techniques for forming electrical connections between microfluidic devices and external circuits. A framework is proposed for the synthesis of a complete glass/silicon device fabrication flow. I. WHY USE SILICON AND GLASS IN MICRO-AND NANO-FLUIDIC APPLICATIONS?Micro-and nano-fluidic technology continues to be embraced by biologists, 1-3 chemists, 4 and engineers throughout academia and industry. As its applications have expanded, there has been an explosion in the range of materials and processes used to fabricate these devices. The earliest microfluidic devices (e.g., gas 5 and liquid 6 chromatography devices) were made from silicon and glass and borrowed processes directly from semiconductor and microelectromechanical systems (MEMS) manufacturing. 7 Now, however, many researchers have moved away from silicon and glass, and instead use cast elastomers such as polydimethylsiloxane (PDMS)-which is ideal for swift prototyping-or thermoplastic polymers, which can be hot-embossed or injection-molded and are well suited to inexpensive manufacturing. Yet, there remain many applications where glass and silicon offer advantages over polymeric materials. In this paper, we highlight these advantages and offer a framework for selecting fabrication processes when using silicon and glass. A. The dominance of soft lithographyOver the last decade, PDMS has become virtually the default material for forming microfluidic devices, 8 because of the sheer ease with which it can be cast on to a micro-scale mould and then strongly bonded to glass. 9 The elastomeric nature of the material has been exploited to integrate fluidic valves and pumps on-chip and has simplified the production of multi-layer devices because the soft layers readily conform to each other. 10,11 Yet, the low stiffness (usually <1 MPa) of PDMS relative to amorphous thermoplastics, silicon, and glass has its own a) Authors to whom correspondence should be addressed. Electronic addresses: ciliescu@ibn.a-star.edu.sg and hkt@ntu.edu.sg. 6, 016505 (2012) drawbacks. High aspect-ratio channels are notoriously difficult to fabricate in PDMS because of their propensity to collapse. 12 Moreover, difficulties in automating the handling of such a soft material have hampered efforts to scale up PDMS device manufacturing. Meanwhile, PDMS's high oxygen and water permeabilities have proved both a blessing and a curse in different applications.The hydrophobic nature of PDMS can be an important consideration for some biological applications. In drug screening applications, for example, hydrophobic drugs as well as metabolites (urea or albumin) can be absorbed into the device's material due to hydrophobic--hydrophobic interaction...

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Section: Wet Etchingmentioning

confidence: 99%

A practical guide for the fabrication of microfluidic devices using glass and silicon

Iliescu¹,

Taylor²,

Avram³

et al. 2012

Biomicrofluidics

310

207

View full text Add to dashboard Cite

show abstract

“…7,8 Similarly, silicon micro-and nano-structures can be formed by chemical etching in alkaline solutions such as potassium hydroxide (KOH) or tetramethyl ammonium hydroxide (TMAH). 9,10 However, producing nano-meter structures with vertical sidewalls utilizing wet chemical etching techniques can be challenging.…”

mentioning

confidence: 99%

Fabrication of High Aspect Ratio Silicon Nanochannel Arrays

Bien

Lee

Saman

2012

ECS Solid State Letters

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We report a method of fabricating an array of high aspect ratio silicon nanochannels which is not dependent on nanolithography techniques and equipment. The method comprises etching of silicon micro-channels in an inductively coupled plasma system (ICP), followed by a thermal oxidation step where silicon is consumed during the process to further shrink the channel to nano dimensions. For the micro-channel formation, silicon dioxide is used as the etch mask during the ICP process where a high etch selectivity of 70:1 between silicon and silicon dioxide was achieved. By thermally oxidizing the etched silicon channels, a uniform array of nanochannels with lateral dimensions down to 40 nm was achieved with significantly high aspect ratio value of at least 65. The grown thermal oxide uniformly covers all surfaces of the silicon nanochannels.

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