Tantalum oxide thin films as protective coatings for sensors

Publication: Research - peer-reviewArticle in proceedings – Annual report year: 1999



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Reactively sputtered tantalum oxide thin-films have been investigated as protective coating for aggressive media exposed sensors. Tantalum oxide is shown to be chemically very robust. The etch rate in aqueous potassium hydroxide with pH 11 at 140°C is lower than 0.008 Å/h. Etching in liquids with pH values in the range from pH 2-11 have generally given etch rates below 0.04 Å/h. On the other hand patterning is possible in hydrofluoric acid. Further, the passivation behaviour of amorphous tantalum oxide and polycrystalline Ta2O5 is different in buffered hydrofluoric acid. By ex-situ annealing in O2 the residual thin-film stress can be altered from compressive to tensile and annealing at 450°C for 30 minutes gives a stress-free film. The step coverage of the sputter deposited amorphous tantalum oxide is reasonable, but metallisation lines are hard to cover. Sputtered tantalum oxide exhibits high dielectric strength and the pinhole density for 0.5 μm thick films is below 3 cm-2
Original languageEnglish
Title of host publicationTwelfth IEEE International Conference on Micro Electro Mechanical Systems, 1999. MEMS '99.
Publication date1999
ISBN (print)0-7803-5194-0
StatePublished - 1999
EventTwelfth IEEE International Conference on Micro Electro Mechanical Systems, 1999. -


ConferenceTwelfth IEEE International Conference on Micro Electro Mechanical Systems, 1999.
Period01/01/1999 → …
SeriesInternational Conference on Micro Electro Mechanical Systems

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CitationsWeb of Science® Times Cited: 6
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