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[摘要]：Microelectromechanical system microhotplates fabricated using silicon-on-insulator wafers were designed and fabricated for accelerated lifetime testing of thin films and nanowires. Thin films of Cr/Ru/Au, Cr/Ru, and Ru were examined as well as nanowires of Ru and RuOx. Rapid thermal cycling at a 1 kHz pulse frequency was employed for testing the thin films. Nanowires were characterized using 1 kHz and 500 Hz pulse frequencies. A 40 nm layer of sputtered Au deposited on 12 nm of sputtered Ru and 8 nm of sputtered Cr displayed a sheet resistance of 1.18 Omega/square and a lifetime of 267 h before failure when cycled with a peak temperature of 692 K. Ru thin films with a thickness of 12 nm displayed a sheet resistance of 51 Omega/square and a lifetime of 10 h under the same conditions. Sputtered Ru and RuOx nanowires with thicknesses of 15 and 32 nm, respectively, displayed resistivities of 72x10(-8) and 320x10(-8) Omega m. It was found that the cycling frequency did not influence the nanowire lifetimes in air or in N-2. Ru nanowires tested in N-2 displayed lifetimes of 450 min followed by Ru nanowires tested in air with lifetimes of 340 min and finally by RuOx nanowires tested in air with lifetimes of 45 min. This latter behavior is attributed to a higher surface diffusion in RuOx compared to Ru. An activation energy of 0.29 eV was observed for failure of Ru nanowires tested in air conditions. Biased percolating behavior with critical exponents ranging from 0.5 to 0.7 was found to describe the electrical behavior for all the nanowires.(C) 2008 American Vacuum Society. |
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