Faculty Publications

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Author: search.filters.author.M.a, M.A.Subject: search.filters.subject.Laser engraving

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    Pulse frequency effect on the NiTi plasmas characteristics and thin film properties and fabrication of NiTi micro-comb structures
    (Elsevier Ltd, 2022) M.a, M.A.; Sidhila, P.S.; Udayashankar, N.K.
    Nickel-titanium (NiTi) is a thermal shape memory alloy (SMA) widely used in the actuator domain in miniaturized systems. With a titanium nitride (TiN) capping layer, NiTi exhibits better mechanical properties and enhances biocompatibility in biomedical applications. In addition, TiN can be efficiently heated to a higher temperature than induce the phase transformation in NiTi MEMS structures. This could be easily achieved by fabricating a TiN heater pattern over or alongside the NiTi MEMS structures. The subject of this work is the NiTi thin films deposited utilizing the pulsed DC magnetron sputter (PDCMS) deposition process at various pulse frequencies (50–350 kHz). The TiN capping layer was also grown on the Si/NiTi stack by the same process. The NiTi micro-comb and TiN micro-heater MEMS structures were fabricated using bulk laser micromachining. Freestanding MEMS structures of NiTi and TiN thin films were realized by etching the bottom silicon with an etch rate of 600 nm/Sec using chemical wet etch by tetramethylammonium hydroxide TMAH. © 2022
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    Development of titanium nitride thin film microheaters using laser micromachining
    (Elsevier Ltd, 2022) M.a, M.A.; Lakshmi Ganapathi, K.L.; Ambresh, M.; Nukala, P.; Udayashankar, N.K.; Mohan, S.
    In this paper, we report the fabrication and characterization of titanium nitride (TiN) thin-film-based microheaters. TiN thin films have been optimized on Si and SiO2 substrates for their optimum electrical resistivities by controlling the process parameters, including argon:nitrogen (Ar:N2) ratio in reactive pulsed DC magnetron sputter (PDCMS) deposition technique. An optical emission spectroscope (OES) was used for monitoring the plasma characteristics at various nitrogen flow rates. The microstructural and surface properties of the TiN films have been investigated and correlated with the electrical properties. It has been observed that the amount of nitrogen flux in the TiN plasma plays an essential role in the microstructural, surface, and electrical properties of the TiN thin films. Micro-heaters have been fabricated with TiN thin films with low electrical resistivity using laser engraving techniques instead of conventional lithographic and micromachining techniques. The TiN microheater has shown excellent performance. A temperature of 406 °C has been achieved by applying an input power of 8 W. This work paves the path for developing scalable and economic TiN microheaters using laser micromachining techniques. © 2021