F UTURE WORK

In this dissertation, we have demonstrated the feasibility of Ni-diamond and Ni-CNT nanocomposites for micromechanical resonator applications. Actually, there are some technical and design issues can be further improved.

Dispersion treatment of nano particle:

The surface treatment of CNTs should be further improved because there are some drawbacks in both treatments used in this dissertation. The drawbacks of SDS: the electrolyte with high SDS concentration would cause foam easily while the electrolyte is pumping with aerating system. This drawback can be eliminated by using stirring system to replace aerating

system. On the other hand, SDS works as a wetting agent which would reduce the Young’s modulus of plated Ni film. The drawbacks of H₂SO₄/H₂O₂: it is hard to remove the H₂SO₄ completely. The residual H2SO4 would lower down the pH level of electrolyte while the treated CNTS is added in it. Extra alkali solution, such as NH₄OH, is necessary for modulating the pH level back to usual. The H2SO4 and NH4OH might cause other chemical compositions and make the electrolyte unstable.

Open area effect:

The width of comb spring/folded beam is 5μm. The width of CC-beam is 25 μm. With the same nano particle concentration, the nanocomposite for CC-beam resonator always reveals higher frequency enhance than comb resonator. It seems that nanoparticle incorporation would be diminished while the open area reduces. It needs to be verified further.

High Q for nanocomposite resonator:

The Ni nanocomposite had been demonstrated in comb and CC-beam resonator but both of them don’t achieve high Q (>1,000). The Q of Ni nanocomposite resonator needs to be verified by the aggressive resonator design, such as free-free beam [11] and disk [13]. Both of them are proposed to achieve high Q.

Reference

[1] C.S. Lam, “A review of the recent development of MEMS and crystal oscillators and their impacts on the frequency control products industry”, Ultrasonics Symposium, San Jose, CA, pp.694-704, 2-5 Nov., 2008.

[2] J. R. Vig, “Quartz crystal resonators and oscillators for frequency control and timing applications-A tutorial”, R&D Technical Report SLCETTR-88-1, AD-A284995, Aug., 1994.

[3] H. C. Nathanson, W. E. Newell, R. A. Wickstrom, J. R. Davis, “The resonant gate transistor”, IEEE Transactions on Electron Devices, 14 (3), pp.117-133, 1967.

[4] W.-T. Hsu and M. Pai, "The new heart beat of electronics-silicon MEMS oscillators", Proc. Electron. Compon. Technol. Conf., pp.1895-1899, 2007.

[5] http://www.discera.com [6] http://www.SiTime.com

[7] K. Wang, “Micromechanical resonator and filter for communications applications”, Ph.D.

Dissertation, Dept. of EECS, University of Michigan, Ann Arbor, 1999.

[8] S. A. Chandorkar, M. Agarwal, R. Melamud, R. N. Candler, K. E. Goodson and T. W.

Kenny, "Limits of quality factor in bulk-mode micromechanical resonators", Proc. IEEE MEMS, Tucson, AZ, pp.74-77, Jan., 2008.

[9] C. T.-C. Nguyen and R. T. Howe, "An integrated CMOS micromechanical resonator high-Q oscillator", IEEE J. Solid-State Circuits, 34, pp.440-455, 1999.

[10] F. D. Bannon III, J. R. Clark, and C. T.-C. Nguyen, “High frequency microelectromechanical IF filters”, Technical Digest, IEEE International Electron Devices Meeting, San Francisco, CA, pp.773-776, 8-11 Dec., 1996.

[11] K. Wang, A.-C. Wong, and C. T.-C. Nguyen, “VHF free-free beam high-Q

micromechanical resonators”, IEEE/ASME J. Microelectromech. Syst., 9 (3), pp.347-360, Sep., 2000.

[12] A. Olkhovets, S. Evoy, D. W. Carr, J. M. Parpia, and H. G. Craighead, “Actuation and internal friction of torsional nanomechanical silicon resonators”, J. Vac. Sci. Technol. B 18, pp.3549-3551, Nov., 2000.

[13] J. R. Clark , W.-T. Hsu , M. A. Abdelmoneum and C.T.-C. Nguyen "High-Q UHF micromechanical radial-contour mode disk resonators", J. Microelectromech. Syst., 14 (6), pp.1298-1310, Dec., 2005.

[14] C. T.-C. Nguyen, "MEMS technology for timing and frequency control", IEEE Trans.

Ultrason., Ferroelectr., Freq. Control, 54 (2), pp.251-270, Feb., 2007.

[15] M. Pandey, R. B. Reichenbach, A T Zehnder, A. Lal, and H. G. Craighead, “ Reducing anchor loss in MEMS resonators using mesa isolation”, IEEE J. Microelectromech.

Syst., 18 (4), pp.836-844, Aug., 2009.

[16] R. Lifshitz, and M. L.Roukes, “Thermoelastic damping in micro- and nanomechanical systems”, Phys. Rev. B, 61, pp.5600-5609, 2000.

[17] Y. Sun, D. Fang, and A.K. Soh, “Thermoelastic damping in micro-beam resonators”, International Journal of Solids and Structures, 43, pp.3213-3229, 2006.

[18] R. Nava, M. P. Vecchi, J. Romero and B. Fernandez, “Akhiezer damping and the thermal conductivity of pure and impure dielectrics”, Phys. Rev. B, 14, (2), pp.800-807, 1975.

[19] W.-L. Huang, Z. Ren, Y.-W. Lin, H.-Y. Chen, J. Lahann, and C. T.-C. Nguyen, “Fully monolithic CMOS nickel micromechanical resonator oscillator”, IEEE 21th International Conference on Micro Electro Mechanical Systems, Tucson, AZ, pp.10-13, 2008.

[20] S. E. Alper, K. M. Silay, and T. Akin, “A low-cost rate-grade nickel microgyroscope”,

15, pp.935-944, 2006.

[22] D. Girbau, L. Pradell, A. Lázaro, and A. Nebot, ”Electrothermally actuated RF MEMS switches suspended on a low-resistibity substrate”, J. Microelectromech. Syst., 16, pp.1061-1070, 2007.

[23] W.-L. Huang, Z. Ren, and C. T.-C. Nguyen, ”Nickel vibrating micromechanical disk resonator with solid dielectric capacitive-transducer gap”, IEEE International Frequency Control Symposium and Exposition, Miami, FL, pp.839-847, 2006.

[24] D. J. Vasquez and J. W. Judy, ”Flexure-based nanomagnetic actuators and their ultimate scaling limits”, IEEE 21th International Conference on Micro Electro Mechanical Systems, Tucson, AZ, pp.737-741, 2008.

[25] C. W. Chang and W. Hsu, ”Three-dimensional micro assembly of a hinged nickel micro device by magnetic lifting and micro resistance welding”, J. Micromech. Microeng., 19, 105026, 2009.

[26] S. A. Lee, J. R. Pinney, M. Bergsneider, and J. W. Judy, ”Magnetic microactuators for MEMS-enabled ventricular catheters for hydrocephalus”, the 3rd International IEEE-EMAS Conference on Neural Engineering, Kohala Coast, HI, pp.65-68, 2007.

[27] A. Cohen, G. Zhang, F. G. Tseng, U. Frodis, F. Mansfeld, and P. Will, ”EFAB rapid, low-cost desktop micromachining of high aspect ratio true 3-D MEMS”, IEEE 12th International Conference on Micro Electro Mechanical Systems, Orlando, FL,

pp.244-251, 1999.

[28] K. Kataoka, T. Itoh, T. Suga, and K. Inoue, ”Contact properties of Ni micro-springs for MEMS probe card”, The 50th IEEE Holm Conference on Electrical Contacts, Seattle, WA, pp.231-235, 2004.

[29] S. E. Alper, I. E. Ocak, and T. Akin, ”Ultrathick and high-aspect-ratio nickel microgyroscope using EFAB multilayer additive electroforming”, J. Microelectromech.

Syst., 16, pp.1025-1035, 2007.

[30] G. Maier, “The search for low-k and ultra-low-k dielectrics: How far can you get with polymers? Part 1: Background”, IEEE Electrical Insulation Magazine, 20 (2), pp.6-17, Dec., 2004.

[31] J. Basu and T. K. Bhattacharyya, “Microelectromechanical resonators for radio frequency communication applications”, Microsystem Technologies , 17, pp.1557-1580, 2011.

[32] W.-T. Hsu and C. T.-C. Nguyen, "Geometric stress compensation for enhanced thermal stability in micromechanical resonators", Proc. IEEE Int. Ultrason. Symp. Dig., pp.945-948, 1998.

[33] W.-T. Hsu, S. Lee, and C. T.-C. Nguyen, "In situ localized annealing for contamination resistance and enhanced stability in nickel micromechanical resonators", Dig. Tech.

Papers, 10th Int. Conf. Solid-State Sensors and Actuators, pp.932 -935, 1999.

[34] S. L. Kuo, Y. C. Chen, M. D. Ger, and W. H. Hwu, “Nano-particles dispersion effect on Ni Al2O3 composite coatings”, Mater. Chem. Phys., 86, pp.5-10, 2004.

[35] L. Orlovskaja, N. Periene, M. Kurtinaitiene, and S. Surviliene, “Ni-SiC composite plated under a modulated current”, Surf. Coat. Technol., 111, pp.234-239, 1999.

[36] K.-S. Teh, Y.-T. Cheng, and L. Lin, “MEMS fabrication based on nickel nanocomposite film deposition and characterization”, J. Micromech. Microeng., 15, pp.2205-2215, 2005.

[37] T.-Y. Chao, G.-R. Shen, and Y.-T. Cheng, “Comparative study of Ni-P-diamonds and Ni-P-CNTs nanocomposite films”, J. Electrochem. Soc., 153, G98-G104, 2006.

[38] L.-N. Tsai, Y.-T. Cheng, W. Hsu, and W. Fang, “Ni-carbon nanotubes nanocomposite for robust microelectromechanical systems fabrication”, J. Vac. Sci. Tech., 24, pp.205-210, 2006.

[39] C.-S. Huang, Y.-T. Cheng, J. Chung, and W. Hsu, “Investigation of Ni-based thermal

electrothermal microactuator using Ni-diamond nanocomposite”, J. Microelectromech.

Syst., 15, pp.149-158, 2006.

[41] C.-S. Huang, Y.-T. Cheng, C.-J. Yeh, H.-K. Liu, and W. Hsu, “Young’s modulus and fatigue limit lifetime improvements by diamond size effect on electroplated Ni-diamond nanocomposite”, the 15th International Conference on Solid-State Sensors, Actuators and Microsystems, Denver, CO, pp.180-183, 2009.

[42] W. C. Tang, T.-C. H. Nguyen, and R. T. Howe, "Laterally driven polysilicon resonant microstructures", Sensors Actuators, 20, pp.25 -32, 1989.

[43] C. T.-C. Nguyen, “Micromechanical Signal Processors”, Ph.D. Dissertation, Dept. of EECS, University of California, Berkeley, 1994.

[44] H. Chen, H. Muthuraman, P. Stokes, J. Zou, X. Liu, J. Wang, Q. Huo, S. I. Khondaker, and L. Zhai, “Dispersion of carbon nanotubes and polymer nanocomposite fabrication using trifluoroacetic acid as a co-solvent”, Nanotech., 18, pp.1-9, 2007.

[45] W. Zhao, C.H. Song, and P.E. Pehrsson, “Water-soluble and optically pH-sensitive single-walled carbon nanotubes from surface modification”, J. Am. Chem. Soc., 124 (42), pp.12418-12419, 2002.

[46] H. T. Ham, Y. S. Choi, Chung, M. G. Chee, and I. J. Chung, “Singlewall carbon nanotubes covered with polystyrene nanoparticles by in-situ miniemulsion polymerization”, J. Poly. Sci. A: Poly. Chem., 44, pp.573-584, 2006.

[47] S. P. Pacheco, L. P. B. Katehi, and C. T.-C. Nguyen, “Design of low actuation voltage RF MEMS switch”, IEEE MTT-S International Microwave Symposium, Boston, MA, pp.165-168, 2000.

[48] D. Peroulis, S. P. Pacheco, K. Sarabandi. and L. P. B. Katehi, “Alleviating the adverse stress effects of residual stress in RF MEMS switches”, the 31st European Microwave Symposium, London, pp.173-176, 2001.

[49] G. C. A. M. Janssen, A. J. Dammers, V. G. M. Sivel, and W. R. Wang, “Tensile stress in

hard metal films”, Appl. Phys. Lett., 83, pp.3287-3289, 2003.

[50] G. C. A. M. Janssen, F. D. Tichelaar, and C. C. G. Visser, “Stress gradients in CrN coatings”, J. Appl. Phys., 100, 093512, 2006.

[51] R. Machunze and G. C. A. M. Janssen, “Stress gradients in titanium nitride thin films”, Surf. Coat. Technol., 203, pp.550-553, 2008.

[52] R. W. Hoffman, “Stresses in thin films: The relevance of grain boundaries and impurities”, Thin Solid Films, 34, pp.185-190, 1976.

[53] J. K. Luo, J. H. He, A. Flewitt, D. F. Moore, S. M. Spearing, N. A. Fleck, and W. I. Milne,

“Development of all metal electrothermal actuator and its applications”, J. Microlithogr.

Microfabr. Microsyst., 4, 023012, 2005.

[54] J. K. Luo, M. Pritschow, A. J. Flewitt, S. M. Spearing, N. A. Fleck, and W. I. Milne,

“Effect of process conditions on properties of electroplated Ni thin film for microsystem applications”, J. Electrochem. Soc., 153, D155-D161, 2006.

[55] M. Saitou, S. Oshiro, and Y. Sagawa, “Scaling behavior of internal stress in electrodeposited nickel thin films”, J. Appl. Phys., 104, 093518, 2008.

[56] A. M. Rashidi and A. Amadeh, “Effect of electroplating parameters on microstructure of nanocrystalline nickel coatings”, J. Mater. Sci. Technol. 26, pp.82-86, 2010.

[57] L. Wang, Y. Gao, T. Xu, and Q. Xue, “A comparative study on the tribological behavior of nanocrystalline nickel and cobalt coatings correlated with grain size and phase structure”, Mater. Chem. Phys., 99, pp.96-103, 2006.

[58] S. He, J. S. Chang, L. Li, and H. Ho, “Characterization of Young's modulus and residual stress gradient of MetalMUMPs electroplated nickel film”, Sens. Actuators, A, 154, pp.149-156, 2009.

Microelectromech. Syst., 8, pp.200-207, 1999.

[61] C.-L. Hsieh and W.-H. Tuan, “Elastic and thermal expansion behavior of two-phase composites”, Mater. Sci. Eng., A, 425, pp.349-360, 2006.

[62] W. D. Callister, Materials Sciense and Engineering: An Introduction, John Wiley & Sons, 1996.

[63] Y. Woo and S.-H. Kim, “Sensitivity analysis of plating conditions on mechanical properties of thin film for MEMS applications”, J. Mater. Sci. Technol., 25, pp.1017-1022, 2011.

[64] W. T. Hsu, "Vibrating RF MEMS for timing and frequency references", Proc. IEEE Int.

Microw. Theory and Tech. Symp., San Francisco, CA, pp.672-675, 2006.

[65] R.Melamud, M. Hopcroft, J. Bongsang, K. Saurabh, R. Candler, and T. W.

Kenny, "Effects of stress on the temperature coefficient of frequency in double clamped resonators," International Conference on Solid State Sensors and Actuators and Microsystems, Seoul, Korea, pp. 392-395, 5-9, June, 2005.

[66] J. Zacharias,” The Temperature Dependence of Young's Modulus for Nickel”, Phys. Rev., 44, pp.116-122, 1933.

[67] C. T.-C. Nguyen, “Micromechanical resonators for oscillators and filters,” Proceedings of the 1995 IEEE International Ultrasonics Symposium, Seattle, WA, pp. 489-499, 7-10

Nov., 1995.

[68] K. Wang and C. T.-C. Nguyen, "High-order medium frequency micromechanical electronic filters", J. Microelectromech. Syst., 8, pp.534-557, 1999.

[69] A.-C. Wong, H. Ding, and C. T.-C. Nguyen, “Micromechanical mixer+filters,” Technical Digest, IEEE International Electron Devices Meeting, San Francisco, California,

pp.471-474, 6-9 Dec., 1998.

[70] M. Yu, "Power-handling capability for RF filters", Microwave Magazines, 8, pp. 88-97, Oct. 2007.

[71] M.-H. Li, W.-C. Chen, and S.-S. Li, “Mechanically-coupled CMOS-MEMS free-free beam resonator arrays with enhanced power handling capability”, IEEE Trans. Ultrason., Ferroelect., Freq. Contr., 59 (3), pp.346-57, Mar., 2012.

[72] S. Lee, “Micromechanical resonator reference oscillators for wireless communications,”

Ph.D. Dissertation, Dept. of EECS, University of Michigan, Ann Arbor, 2006.

Publication list

Journal papers

1. Yi-Chia Lee, Yu-Ting Chengand Wensyang Hsu, “Stress Gradient Modification of the Electroplated Ni-Diamond Nanocomposite for MEMS Fabrication”, Journal of The Electrochemical Society, 159 (4), H460-H466, 2012.

2. Yi-Chia Lee, Ming-Huang Li, Y. T. Cheng, Wensyang Hsu, and Sheng-Shian Li,

“Electroplated Ni-CNT Nanocomposite for Micromechanical Resonator Applications”, IEEE Electron Device Letters, 33 (6), pp. 872-874, June, 2012.

Conference papers

1. Yi-Chia Lee, Li-Nuan Tsai, Yu-Ting Cheng, and Wensyang Hsu, “Performance Enhancement of Comb Drive Actuators Utilizing Electroplated Nickel-Diamond Nanocomposite”, Proceedings of the 3th Asia-Pacific Conference on Transducers and Micro-Nano Technology (APCOT 2006), Singapore, June 25-28, 2006.

2. Yi-Chia Lee, Yu-Ting Cheng, and Wensyang Hsu, “Process Effect of Electroplated Ni and Ni-Diamond Nanocomposite Film on the Stress Distribution of Micromechanical Structure”, Proceedings of the 4th Asia-Pacific Conference on Transducers and Micro-Nano Technology (APCOT 2008), Tainan, Taiwan, June 22-25, 2008.

3. Hsuan-Yu Lin, Yi-Chia Lee, and Wensyang Hsu, “A Rapid Fatigue Test Method on Microstructures”, Proceedings of the 5th Asia-Pacific Conference on Transducers and Micro-Nano Technology (APCOT 2010), Perth, Australia, July 6-9, 2010.

4. Yi-Chia Lee, Yu-Ting Cheng, and Wensyang Hsu, “Electroplating Process of Ni-CNTs Nanocomposite for MEMS Resonator Fabrication”, Proceedings of the 24th International Conference on Micro-Electro-Mechanical-Systems (MEMS2011), Cancun, Mexico, January 23-27, 2011.