Chemical etching of Tungsten thin films for high-temperature surface acoustic wave-based sensor devices

Spindler, M. W.; Herold, S.; Acker, Jörg; Brachmann, Erik; Oswald, Steffen; Menzel, S.; Rane, Gayatri K.

doi:10.1016/j.tsf.2016.04.035

Cited by 8 publications

(4 citation statements)

References 14 publications

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“…10-13. W metallic 4f 7/2 and 4f 5/2 peaks are located at 31.6 and 33.8 eV and those of WO 3 peaks are located at 35.6 and 37.8 eV, 21,22 respectively, as shown in Fig. 4a.…”

Section: Resultsmentioning

confidence: 80%

Influence of Scavenger on Abrasive Stability Enhancement and Chemical and Mechanical Properties for Tungsten-Film Chemical- Mechanical-Planarization

Seo

Bae

Kim

et al. 2020

ECS J. Solid State Sci. Technol.

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In tungsten(W)-film chemical-mechanical-planarization(CMP), Fenton reaction between ferric-based-catalyst and oxidant hydrogen peroxide (H2O2) enhances the chemical-oxidation degree of the W-film surface and degrades the abrasive stability of a W-film CMP-slurry as a trade-off effect. The addition of a scavenger (i.e., trilithium citrate tetrahydrate: TCT–Li) in the W-film CMP-slurry improved significantly the abrasive stability. A ionized scavenger (i.e., citrate ions) produced a Fe(III)-citrate complex and chemically reacted with the reactive radicals (i.e., OH·, HO2· and O2·−), depressing Fenton reaction in a ferric-catalyst-based W-film CMP-slurry. Hence, the abrasive stability of the W-film CMP-slurry was improved with the scavenger concentration. In addition, TCT–Li influenced mainly the chemical properties such as the chemical-oxidation degree for the W-film surface and the hydrolysis degree of the SiO2-film surface. Thus, the W-film polishing-rate slightly decreased with the scavenger concentration while the SiO2-film peaked at a specific scavenger concentration (i.e., 0.1-wt%). In addition, two chemical reaction regions were found; i.e., the scavenger-concentration dominant chemical-reaction at the region I (i.e., TCT–Li 0 ∼ 0.1 wt%) and the catalyst [i.e., Fe(NO3)3]-concentration dominant chemical-reaction at the region II (i.e., TCT–Li 0.1 ∼ 0.3 wt%). The region I showed more strongly a chemical-dominant-reaction than the region II, determining the W- and SiO2-film polishing-rate.

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“…10-13. W metallic 4f 7/2 and 4f 5/2 peaks are located at 31.6 and 33.8 eV and those of WO 3 peaks are located at 35.6 and 37.8 eV, 21,22 respectively, as shown in Fig. 4a.…”

Section: Resultsmentioning

confidence: 80%

Influence of Scavenger on Abrasive Stability Enhancement and Chemical and Mechanical Properties for Tungsten-Film Chemical- Mechanical-Planarization

Seo

Bae

Kim

et al. 2020

ECS J. Solid State Sci. Technol.

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“…While most of our channels were made based on a 25 μm mandrel, we have successfully tested larger diameter wires up to 100 μm. Tungsten wire is commercially available down to 15 μm and can be etched to smaller diameters with H 2 O 2 , perhaps most conveniently after the wire has already been fixed in the molding structure. Making smaller channels should thus be possible, especially as the polymer expands in the latter stage, releasing the wire.…”

Section: Resultsmentioning

confidence: 99%

Moldable Strong Cation Exchange Polymer and Microchannel Fabrication

Maleki

Dasgupta

2020

Anal. Chem.

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We characterize a high-capacity cation exchange membrane (CEM) synthesized from an aqueous poly(vinyl alcohol) (PVA) solution and varying amounts of a water-soluble ionic monomer, sodium styrenesulfonate. Highly hydrophilic but waterinsoluble transparent polymers with a range of ion exchange capacities (IECs) can be made; at the high end, the ion exchange capacities (IEC) is >2× that of the benchmark CEM, Nafion. The water uptake of the polymer (as moles of water/mole H + ) is 5−10× greater than that of Nafion. Except at the highest IECs (where steeply increasing water sorption and resultant swelling outpaces IEC increase), the specific conductance increases with increasing IEC while the conductance anisotropy decreases. The material withstands repeated regeneration cycles and hour-long boiling in water or alcohols. The aqueous prepolymer mixture can be cast around a fine wire acting as a mandrel. Fabrication of an ion exchanger microchannel, capable of withstanding at least 300 psi, is demonstrated. We also discuss entirely novel considerations on ab initio limits of conductance of ion exchange membranes.

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“…A. 4 In the second term on the right-hand side of Eq. (A13), f is the other fitting parameter of the model and represents the fraction of the discharge voltage falling over the IR.…”

Section: A25 Argon Ions Dn Armentioning

confidence: 99%

“…Due to their unique thermophysical, electrical and mechanical properties, tungsten (W) films have application in various industrial and research fields. For instance, W films have been studied for microelectronics industry [1,2], x-ray lithography [3] and surface acoustic wave sensors production [4]. Furthermore, they are also exploited in the energy sector [5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%