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李毅家 (Yi-Chia Lee)
李毅家 (Yi-Chia Lee)
Electroplated Ni-Diamond and Ni-CNT Nanocomposites for Micromechanical Resonator Applications
電鍍鎳基奈米鑽石與奈米碳管複合材料於微機械式共振器之應用
電鍍鎳基奈米鑽石與奈米碳管複合材料於微機械式共振器之應用
Quartz plays an important role for time and frequency reference in wireless and consumer electronic systems. Unfortunately, quartz resonator is not easy to integrate with other electronics directly. Currently, micromechanical resonator has become an alternative device to replace quartz resonator for better integration. Based on the technology trend, this dissertation explores the feasibility of electroplated Ni-diamond and Ni-CNT (Ni-Carbon Nanotube) nanocomposites for micromechanical resonator applications and proposes a proper fabrication process where good particle dispersion characteristics including nano diamonds and CNTs in electrolyte can be obtained to fully adopt the physical properties of the nano materials for achieving composite effects. The nano diamond and CNT particles can exhibit good dispersion using ultrasonication and the surface treatment of H2SO4/H2O2 and SDS water solution, respectively, that result in better frequency enhancement in nanocomposite micromechanical resonators. Meanwhile, as-plated Ni-based nanocomposite film is usually accompanied with residual stress that would cause significant undesired structural deformation. The stress issue can be evidently reduced by lowering plating current density. For the films plated with the density reduction from 15.3 mA/cm2 to 0.8 mA/cm2, about 41%~21% stress gradient reduction can be realized. Experimental results show that the stress gradients are -3.23, -5.65, and -4.75 MPa/μm for Ni, Ni-diamond, and Ni-CNT plate with 0.8 mA/cm2, respectively. The stress gradients are low enough to achieve a fully suspended micromechanical structure without any noticeable deformation. In addition, 39% and 46% of E/ρ enhancements can be achieved by the nano diamond (2 g/L) and CNTs (1 g/L) incorporations, respectively. The higher the E/ρ ratio is, the higher resonant frequency performance will be in the micromechanical resonators. Thus, in the work, comb and CC-beam designs are adopted for the validation of the performance improvement of the micromechanical resonators made of the nanocomposites. Measurement results show 14% and 8% and 45% and 27% of frequency enhancements can be obtained in both of the comb resonators made of the Ni-diamond (2 g/L) and Ni-CNT (0.028 g/L) and the CC-beam resonators made of nano diamond (2 g/L) and CNTs (1 g/L), respectively. The results also indicate no Q degradation happens in these nanocomposite resonators.
Quartz plays an important role for time and frequency reference in wireless and consumer electronic systems. Unfortunately, quartz resonator is not easy to integrate with other electronics directly. Currently, micromechanical resonator has become an alternative device to replace quartz resonator for better integration. Based on the technology trend, this dissertation explores the feasibility of electroplated Ni-diamond and Ni-CNT (Ni-Carbon Nanotube) nanocomposites for micromechanical resonator applications and proposes a proper fabrication process where good particle dispersion characteristics including nano diamonds and CNTs in electrolyte can be obtained to fully adopt the physical properties of the nano materials for achieving composite effects. The nano diamond and CNT particles can exhibit good dispersion using ultrasonication and the surface treatment of H2SO4/H2O2 and SDS water solution, respectively, that result in better frequency enhancement in nanocomposite micromechanical resonators. Meanwhile, as-plated Ni-based nanocomposite film is usually accompanied with residual stress that would cause significant undesired structural deformation. The stress issue can be evidently reduced by lowering plating current density. For the films plated with the density reduction from 15.3 mA/cm2 to 0.8 mA/cm2, about 41%~21% stress gradient reduction can be realized. Experimental results show that the stress gradients are -3.23, -5.65, and -4.75 MPa/μm for Ni, Ni-diamond, and Ni-CNT plate with 0.8 mA/cm2, respectively. The stress gradients are low enough to achieve a fully suspended micromechanical structure without any noticeable deformation. In addition, 39% and 46% of E/ρ enhancements can be achieved by the nano diamond (2 g/L) and CNTs (1 g/L) incorporations, respectively. The higher the E/ρ ratio is, the higher resonant frequency performance will be in the micromechanical resonators. Thus, in the work, comb and CC-beam designs are adopted for the validation of the performance improvement of the micromechanical resonators made of the nanocomposites. Measurement results show 14% and 8% and 45% and 27% of frequency enhancements can be obtained in both of the comb resonators made of the Ni-diamond (2 g/L) and Ni-CNT (0.028 g/L) and the CC-beam resonators made of nano diamond (2 g/L) and CNTs (1 g/L), respectively. The results also indicate no Q degradation happens in these nanocomposite resonators.
[1] Y.-C. Lee, L.-N. Tsai, Y.-T. Cheng and W. Hsu (June 2006). Performance Enhancement of Comb Drive Actuator Utilizing Electroplated Nickel-Diamond Nanocomposite, The 3rd Asia-Pacific Conference of Transducers and Micro-Nano Technology, Singapore.
[1] Y.-C. Lee, L.-N. Tsai, Y.-T. Cheng and W. Hsu (June 2006). Performance Enhancement of Comb Drive Actuator Utilizing Electroplated Nickel-Diamond Nanocomposite, The 3rd Asia-Pacific Conference of Transducers and Micro-Nano Technology, Singapore.
[2] J. Chung, Y.-C. Lee, and W. Hsu (January 2008). Fabrication of polymer-based vertical comb drive using a double-side multiple partial exposure method, The 21th IEEE International Conference on Micro Electro Mechanical Systems, Tucson, U.S.A..
[2] J. Chung, Y.-C. Lee, and W. Hsu (January 2008). Fabrication of polymer-based vertical comb drive using a double-side multiple partial exposure method, The 21th IEEE International Conference on Micro Electro Mechanical Systems, Tucson, U.S.A..
[3] H.-Y. Lin, Y.-C. Lee, and W. Hsu (July 2010). A Rapid Fatigue Test Method on Microstructures, 5th Asia-Pacific Conference on Transducers and Micro-Nano Technology, West Australia.
[3] H.-Y. Lin, Y.-C. Lee, and W. Hsu (July 2010). A Rapid Fatigue Test Method on Microstructures, 5th Asia-Pacific Conference on Transducers and Micro-Nano Technology, West Australia.
[4] Y.-C. Lee, Y.-T. Cheng and W. Hsu, “Stress Gradient Modification of the Electroplated Ni-Diamond Nanocomposite for MEMS Fabrication.” Journal of The Electrochemical Society, 2012, 159, 460-466.
[5] Y.-C. Lee, M.-H. Li, Y.-T. Cheng, W. Hsu, and S.-S. Li, "Electroplated Ni-CNT Nanocomposite for Micromechanical Resonator Applications." IEEE Electron Device Letters 2012, 33, 872-874.
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