Etch rates for micromachining processing-part II

Williams, K.R.; Gupta, Kapil; Wasilik, Matthew

doi:10.1109/jmems.2003.820936

Cited by 874 publications

(617 citation statements)

References 11 publications

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“…Based on the fact that zirconium dioxide can be dissolved in hydrofluoric acid (HF) [42] while α-alumina is highly resistant to HF [43], a selective removal of the zirconia phase was achieved by immersing the samples in concentrated HF (Hydrofluoric Acid 40% QP, Panreac, Barcelona, Spain) at room temperature for times comprised between 6 h, 1, 2, 4, 8 and 12 days.…”

Section: Generation Of Nano-roughness and Interconnected Porosity By mentioning

confidence: 99%

Selective etching of injection molded zirconia-toughened alumina: Towards osseointegrated and antibacterial ceramic implants

et al. 2016

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Due to their outstanding mechanical properties and excellent biocompatibility, zirconiatoughened alumina (ZTA) ceramics have become the gold standard in orthopedics for the fabrication of ceramic bearing components over the last decade. However, ZTA is bioinert, which hampers its implantation in direct contact with bone. Furthermore, periprosthetic joint infections are now the leading cause of failure for joint arthroplasty prostheses. To address both issues, an improved surface design is required: a controlled micro-and nano-roughness can promote osseointegration and limit bacterial adhesion whereas surface porosity allows loading and delivery of antibacterial compounds. In this work, we developed an integrated strategy aiming to provide both osseointegrative and antibacterial properties to ZTA surfaces. The microtopography was controlled by injection molding. Meanwhile a novel process involving the selective dissolution of zirconia (selective etching) was used to produce nano-roughness and interconnected nanoporosity. Potential utilization of the porosity for loading and delivery of antibiotic molecules was demonstrated, and the impact of selective etching on mechanical properties and hydrothermal stability was shown to be limited. The combination of injection molding and selective etching thus appears promising for fabricating a new generation of ZTA components implantable in direct contact with bone.3

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Section: Generation Of Nano-roughness and Interconnected Porosity By mentioning

confidence: 99%

Selective etching of injection molded zirconia-toughened alumina: Towards osseointegrated and antibacterial ceramic implants

et al. 2016

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“…The native aluminum oxide layer, Al 2 O 3 , overhangs the underlying metal and serves as a mask during the deposition of the second electrode. This layer must be removed afterwards, but since Al 2 O 3 , corundum, is one of the most chemically inert materials [17], removal by direct chemical etching is very difficult. In a refinement, the authors deposited an additional sacrificial layer of SiO 2 and subsequently used etchant for SiO 2 to remove the SiO 2 and Al/Al 2 O 3 layers [16].…”

mentioning

confidence: 99%

Nanogaps with very large aspect ratios for electrical measurements

Fursina

Lee

Sofin

et al. 2008

Applied Physics Letters

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For nanoscale electrical characterization and device fabrication it is often desirable to fabricate planar metal electrodes separated by large aspect ratio gaps with interelectrode distances well below 100 nm. We demonstrate a self-aligned process to accomplish this goal using a thin Cr film as a sacrificial etch layer. The resulting gaps can be as small as 10 nm and have aspect ratios exceeding 1000, with excellent interelectrode isolation. Such Ti/Au electrodes are demonstrated on Si substrates and are used to examine a voltage-driven transition in magnetite nanostructures. This shows the utility of this fabrication approach even with relatively reactive substrates.PACS numbers: 81.07. -b,81.16.-c,85.35.-p There is much interest in the electronic characterization of nanoscale materials and the creation of working molecular-based devices [1]. Both goals demand the fabrication of metallic electrodes separated by a distance comparable with the targeted length, i.e. a few nanometers. Much recent progress has been made in nanogap fabrication, and several techniques were proposed, including electromigration [2,3,4], electrodeposition [5,6], mechanically controlled break junctions [7], advanced ebeam lithography methods [8,9,10,11,12], on-wire lithography [13], etc. Interelectrode distances down to 1-2 nm may be achieved [4,6,9] by some of these methods, though without much control of gap aspect ratio.A significant challenge is fabricating two electrodes separated by a nanometer gap running parallel over a macroscopic width (high-aspect-ratio (HAR) nanogaps). HAR nanogap fabrication has been demonstrated based on a selective etching of cleaved GaAs/AlGaAs heterostructures [14,15]. However, this method requires particular substrates and allows only restricted gap geometries. A much simpler technique was proposed recently [16] with potentially no limitations on the width of the gap. Two separate lithographic patterning steps are used to define first and second electrodes, while the interelectrode separation is controlled by the oxidation of an Al sacrificial layer deposited upon the first electrode. The native aluminum oxide layer, Al 2 O 3 , overhangs the underlying metal and serves as a mask during the deposition of the second electrode. This layer must be removed afterwards, but since Al 2 O 3 , corundum, is one of the most chemically inert materials [17], removal by direct chemical etching is very difficult. In a refinement, the authors deposited an additional sacrificial layer of SiO 2 and subsequently used etchant for SiO 2 to remove the SiO 2 and Al/Al 2 O 3 layers [16]. The use of SiO 2 etchant greatly limits the use of this approach in conjunction with conventional silicon electronics. While this method potentially allows fabrication of HAR nanogaps, the reported aspect ratios are less than 10 [16].In this letter we report a highly reproducible and flexible method for nanometer-sized (10-20 nm) gap fabrication with aspect ratios exceeding 1000. Modifying the original method [16] by replacing the Al layer wi...

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“…The same deposition parameters are used as during the first layer to deposit a layer of 1.5 μm. Here the LPCVD SiRN is used because of its chemical inertness, high strength, stability and good thermal properties (Williams and Muller 1996;Gardeniers et al 1996;French et al 1997;Freitag and Richerson 1998;Williams et al 2003;Kaushik et al 2005). In addition, it is biocompatible (Mazzocchi and Bellosi 2008), its surface can be functionalized (Parvais et al 2003;Arafat et al 2004) and the stress in SiRN can be tuned by the deposition parameters (Gardeniers et al 1996;Habermehl 1998) which allows relatively thick layers.…”

Section: Fabrication Outline When Using Standard Silicon Wafersmentioning

confidence: 99%

A versatile technology platform for microfluidic handling systems, part I: fabrication and functionalization

Groenesteijn

Boer

Lötters

et al. 2017

Microfluid Nanofluid

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often have to be connected using (external) fluidic interconnects. This way, the fluidic interconnects will have a relatively large volume, resulting in slow response times and requiring large sample sizes.To make the ideal integrated microfluidic handling system, one fabrication process should allow many different microfluidic devices for all kinds of applications to be integrated on the same chip. The functional channels of the devices, the interconnect channels and the required interfacing electronics should be integrated on the same substrate without restricting the design options for each device.Different applications pose different demands on the fabricated system. To avoid leakage and wear, the channel walls should be mechanically strong, chemically inert and leak tight for both liquids and gasses in a large temperature range. It should be possible to locally release the channel (completely or partially) from the substrate, e.g. for thermal isolation or freedom of movement. It is required to integrate transducer structures for actuation and measurement of the devices. This can be anything from metal tracks to piezoelectric or magnetic materials or optical waveguides. Functionalization of the inside of the channel, e.g. with a catalyst or with specific coatings for (bio)chemical reactions or adhesion should be possible. Multiple channels should be able to cross each other or run inside each other. Interface electronics should be integrated directly on the chip or package to reduce noise and other parasitic effects.To be able to transfer proof-of-concepts to commercial devices, it should not only be possible to fabricate low-volume research devices, but it should also be possible to scale up the fabrication to industrial low-cost, high-volume processing in foundries. Last, and certainly not least, it should be straightforward to design the optimal fluidic element with respect to shape and size, for any application. AbstractMany microfluidic devices are made using specialized fabrication processes, limiting the ability to integrate those devices on the same chip. In this paper, a versatile technology platform is presented that allows for integration of many different devices. It provides a method to design channels in a wide range of sizes and shapes with different functionalization options in close proximity to the fluid in the channels. The latter includes release of the channels for thermal isolation or mechanical movement and metal or piezoelectric layers for actuation and read-out. The channel walls are made using silicon-rich silicon nitride to provide durable, strong, chemically inert and thermally stable channels directly below the substrate surface .

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Etch rates for micromachining processing-part II

Abstract: [1070]

Cited by 874 publications

References 11 publications

Selective etching of injection molded zirconia-toughened alumina: Towards osseointegrated and antibacterial ceramic implants

Selective etching of injection molded zirconia-toughened alumina: Towards osseointegrated and antibacterial ceramic implants

Nanogaps with very large aspect ratios for electrical measurements

A versatile technology platform for microfluidic handling systems, part I: fabrication and functionalization

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