Browsing by Author "Cheng, YT"

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A closed-form integral model of spiral inductor using the Kramers-Kronig relations
(2005-11-01)
Chen, CC
;
Huang, JK
;
Cheng, YT
;
電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
In this letter, a closed-form integral model is presented for the rectangular micromachined spiral inductor. The Kramers-Kronig relations provide an elegant theory to describe the inductor behavior without having complicated geometric analysis. Simulation and measurement results validate that the model can provide satisfactory prediction to the inductance of on-chip freely-suspended spiral inductors. Meanwhile, unlike conventional Greenhouse-based formulations, the self-resonant frequency of inductor can be predicted using the integral model.
A low temperature wafer-level hermetic MEMS package using UV curable adhesive
(2004)
Liang, ZH
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Cheng, YT
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Hsu, W
;
Lee, YW
;
電子工程學系及電子研究所
In order to lower the packaging cost and resolve the process complexity of MEMS fabrications, a new wafer-level post-process hermetic package using UV curable adhesive bonding is introduced for MEMS applications. The UV curable adhesive is cured through UV light exposure without any additional heating, suitable for packaging the devices with temperature sensitive materials or processes. A Pyrex 7740 glass is micromachined and used as a protection cap substrate with microcavities which is spin-coated with the adhesive, aligned, and bonded with a device substrate to form the package after the UV curing. Finally, electrical contact pads expose and die separation are done simultaneously by dicing. Two different monitoring devices, dew point sensor and capacitive accelerometer are built to evaluate the package strength and hermeticity. After dicing operation, no structure damage or stiction phenomenon is found in the packaged capacitive accelerometer. Furthermore, no moisture condensation is observed in the package with 190mum bonding width after 150 minutes boil water immersion. The acceleration test results indicate the package can survive more than 3 weeks at 25degreesC, 100% R.H. (Relative Humidity) working environment.
A robust high-Q micromachined RF inductor for RFIC applications
(2005-07-01)
Lin, JW
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Chen, CC
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Cheng, YT
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this paper, a robust micromachined spiral inductor with a cross-shaped sandwich membrane support is proposed and fabricated with fully CMOS compatible post-processes for radio frequency integrated circuit (RFIC) applications. Via the incorporation of a sandwich dielectric membrane (0.7 mu M SiO2/0.7 mu M Si3N4/0.7 mu m TEOS) to enhance the structure rigidity, the inductor can have better signal stability. In comparison, the new design of a similar to 5-nH micromachined inductor can have 45% less inductance variation than the one without the dielectric support while both devices are operated with 10 m/s(2) acceleration. Meanwhile, using a cross shape instead of blanket membrane can also effectively eliminate the inductance variation induced by the working temperature change (20 degrees C to 75 degrees C). The measurement results show the robust inductor can have similar electrical performance to the as-fabricated freely suspended inductor, which has five times Q (quality factor) improvement than the inductor without the substrate removal. It is our belief that the new micromachined inductors can have not only high-Q performance but also better signal stability suitable for wide-range RFIC applications.
An optimum design of the micromachined RF inductor
(2004)
Lin, JW
;
Chen, CC
;
Huang, JK
;
Cheng, YT
;
電子工程學系及電子研究所
With a complete performance investigation of the on-chip micromachined inductor with mechanical disturbances using ANSYS and HFSS simulators, an optimum structural design of the micromachined spiral inductors with fully CMOS compatible post-processes for RFIC applications is proposed in this paper. Via the incorporation of a sandwich dielectric membrane (0.7mum SiO2/ 0.7mum Si3N4/ 0.7mum TEOS) to enhance the structure rigidity, the inductor can have better signal stability. As compared, the new design of a 5nH micromachined inductor can have less 45% inductance variation than the conventional one while both devices operate at 8GHz but with 10 m/sec(2) acceleration. Meanwhile, using a cross shape instead of blanket membrane can also effectively eliminate the inductance variation induced by the working temperature change (20degreesC to 75degreesC). It's our belief that the new micromachined inductors can have not only high Q performance but also better signal stability suitable for wide range RFIC applications.
Comparative study of Ni-P-diamond and Ni-P-CNT nanocomposite films
(2006)
Chao, TY
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Shen, GR
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Cheng, YT
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電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Ni-P-diamond and Ni-P carbon nanotube (CNT) nanocomposite films have been synthesized and compared in this paper. Because diamond has different shapes and sizes than CNTs, the nanocomposite films exhibit distinct characteristics. Nanoindentation measurements show that the Young's modulus and hardness of the Ni-P-CNT nanocomposite film electroplated in a bath with 0.028 g/L CNTs increase to 665.9 +/- 29.5 GPa and 28.9 +/- 4.22 GPa, respectively, which is about four times larger than that of pure nickel. On the contrary, the modulus and hardness of the Ni-P-diamond nanocomposite films decrease with the incorporation of the nanodiamond powders due to the formation of voids and cracks, even though both diamond and CNTs have similar Young's modulus and hardness. For the Ni-P-diamond film plated in the bath with 2.0 g/ L nanodiamonds, the values are reduced to 110.5 +/- 4.3 and 2.3 +/- 0.1 GPa. Nevertheless, the electrothermal actuators made of both Ni-P-CNT and Ni-P-diamond composites can provide four times the maximum elongation, larger than that made of pure nickel. With the same displacement, the input power of the nanocomposite actuators is much less than that of the pure Ni one. This study reveals potential applications for nano/microelectromechanical systems fabrication using both Ni-P-diamond and Ni-P-CNT nanocomposites due to their distinctive physical properties and compatibility with contemporary complementary metal oxide semiconductor manufacturing processes. (c) 2005 The Electrochemical Society. [DOI: 10.1149/ 1.2133324] All rights reserved.
MEMS fabrication based on nickel-nanocomposite: film deposition and characterization
(2005-12-01)
Teh, KS
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Cheng, YT
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Lin, LW
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電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Electrosynthesized metal-nanocomposites represent a unique class of microelectromechanical systems (MEMS) structural material due to their compatibility with MEMS and CMOS fabrication technologies via a one-step, selective on-chip deposition process at low temperatures (similar to 50-90 degrees C). In this paper, particle-reinforced, electrosynthesized nickel-nanocomposites of various compositions have been successfully demonstrated as potential structural materials for MEMS. We have achieved low-temperature, stress-free, wafer-level fabrication of nano-composite MEMS via both an electroless nickel (EN) and an electrolytic nickel (EL) deposition process, with the addition of uniformly dispersed micro- and nanoparticles of either cordierite (diameter approximate to 100 nm-5 mu m) or diamond (diameter similar to 4 nm). The as-deposited nickel-cordierite films exhibit better thermal compatibility with silicon, compared to nickel. The measured coefficients of thermal expansion (CTE) of EN-cordierite and EN are 17.34 ppm K-1 and 26.69 ppm K-1, respectively. Stress-temperature measurement of EN-cordierite composite also confirms that residual stress decreases with the incorporation of cordierite. Finally, by adding various concentrations of nanodiamond particles into an EL matrix, It is found that higher diamond concentration renders these films more compressively stressed.
Nanocomposite effects on the coefficient of thermal expansion modification for high performance electro-thermal microactuator
(2005)
Tsai, LN
;
Cheng, YT
;
Hsu, WS
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
We employ a low-temperature stress-free electroplated nickel (EL) process with the addition of uniformly dispersed nanoparticles of diamond (< 500 nm) or SiO2 (< 80 nm) to investigate "nanocomposite effects" for the first time on the modification of the thermal expansion coefficient (CTE) and other mechanical properties of nickel and its correlation to power and reliability improvement of electro-thermal microactuators. Experimental results show that these material parameters can be either enhanced or deteriorated via the incorporation of different kind of nanopowders. Although the mechanical strength enhancement can be attributed to the intrinsic characteristics of the nanoparticle based on the rule of mixture, the discrepancy of CTE modification can only be explained with distinct composite microstructures which result in the performance improvement of the electro-thermal microactuator. This work has led to a possible research direction in the development of MEMS using the nanocomposites.
Ni-carbon nanotubes nanocomposite for robust microelectromechanical systems fabrication
(2006-01-01)
Tsai, LN
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Cheng, YT
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Hsu, WS
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Fang, WL
;
電子工程學系及電子研究所
This article presents a novel fabrication process to enhance the operational performance and reliability of electrothermal microactuators. Carbon nanotubes (CNTs) (outer diameter: 10-20 nm, innerdiameter: 5-10 nm, length: 0.5-200 mu m) are incorporated in an electrolytic nickel deposition process in which a well-dispersed Ni-CNTs colloidal solution is made by a special acid oxidative method to synthesis a Ni-CNTs nanocomposite for device fabrication. Measurement results show that the microactuator plated with CNTs (0.028 g/L) needs the power requirement less 95% than the pure nickel device at the same output displacement of 3 mu m. The performance improvement of the electrothermal microactuator made of the nanocomposite, including device strength and power efficiency, has shown to be similar to the Ni-diamond composites (L. N. Tsai, G. R. Shen, Y. T. Cheng, and W. S. Hsu, The 54th Electronic Components and Technology Conference, June 2004, pp. 472-476)). In addition, the E/p ratio of the Ni-CNTs composite can be enhanced to 1.47 times higher than that of pure nickel, which is a fascinating result for resonant device fabrication. (c) 2006 American Vacuum Society.
Ni-P-CNTs nanocomposite film for MEMS applications
(2004)
Shen, GR
;
Tsai, LN
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Chao, TY
;
Cheng, YT
;
Lin, TK
A Ni-P-CNTs (electroless phosphorus nickel-carbon nanotubes) nanocomposite film synthesis and related processes for MEMS device fabrication have been successfully developed and presented in this paper. With a special acid oxidative method, a well-dispersed nickel-CNTs colloidal solution has been produced without any aggregation, very suitable for microstructure fabrication. The nano-indentation measurement indicates that the Young's modulus and hardness of the Ni-P-CNTs nanocomposite film plated in the bath with 0.028g/L CNTs can greatly increase up to 666Pa and 29GPa, respectively, which is four times larger than that of pure nickel: The performance improvement of the electro-thermal microactuator made of the nanocomposite, including device strength and power efficient, have been proved similar to the Ni-diamond composites [1]. With the same power input, the device can provide 4 times elongation longer than that made of pure nickel. The mechanical strength of the actuator can also be enhanced to sustain the input power with two times larger than the pure one.
Performance improvement of an electrothermal microactuator fabricated using Ni-diamond nanocomposite
(2006-02-01)
Tsai, LN
;
Shen, GR
;
Cheng, YT
;
Hsu, W
;
電子工程學系及電子研究所
In this paper, a low-temperature stress-free electrolytic nickel (EL) deposition process with added dispersed diamond nanoparticles (diameter < 0.5 mu m) is developed to synthesize Ni-diamond nanocomposite for fabricating electrothermal microactuators. Device characterization reveals dramatic performance improvements in the electrothermal microactuator that is made of the nanocomposite, including a reduction in the input power requirement and enhanced operation reliability. In comparison with the microactuator made of pure nickel, the nanocomposite one can save about 73% the power for a 3 mu m output displacement and have a longer reversible displacement range, which is prolonged from 1.8 mu m to more than 3 mu m. Furthermore, the nanocomposite device exhibits no performance degradation after more than 100 testing cycles in the reversible regime. The enhancements increase with the incorporation of the nanodiamond in a nickel matrix, so the Ni-diamond nanocomposite has potential for application in MEMS fabrication.
Power and reliability improvement of an electro-thermal microactuator using Ni-diamond nanocomposite
(2004)
Tsai, LN
;
Shen, GR
;
Cheng, YT
;
Hsu, W
;
電子工程學系及電子研究所
Here a low-temperature stress-free electrolytic nickel (EL) deposition process with the addition of uniformly dispersed diamond nanoparticles (diameter < 0.5 mum) is propose to fabricate cantilevers and electro-thermal microactuators to demonstrate the improvement of the device on reducing input power requirement and enhancing operation reliability. The fabrication results show that the nanodiamond particles are successfully dispersed in the electroplating nickel layers. By calibrating the resonant frequencies of nickel cantilevers with different concentrations of diamond nanoparticles, the E/pratio of cantilevers can be enhanced 7.1 times with diamond nanoparticles of 2 g/l in the proposed electrolytic nickel (EL) deposition process. From displacement tests, the electro-thermal microactuator with nanodiamond particles of 2 g/l reduces 73% power requirement of pure nickel device needed at the same output displacement of 3 mum. Also, the reversible displacement range is found to be expanded from 1.8 mum to 3 mum by adding nanodiamond particles of 2 g/l in the nickel electro-thermal microactuators.
Synthesis and characterization of Ni-P-CNT's nanocomposite film for MEMS applications
(2005-09-01)
Shen, GR
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Cheng, YT
;
Tsai, LN
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機械工程學系
;
電子工程學系及電子研究所
An electroless phosphorus nickel-carbon nanotube's (Ni-P-CNT) nanocomposite film synthesis and related process for microelectromechanical systems device fabrication have been successfully developed and presented in this paper. With a special acid oxidative method, a well-dispersed nickel-CNT's colloidal solution has been produced without any aggregation, which is very suitable for microstructure fabrication. The nanoindentation measurement indicates that the Young's modulus and hardness of the Ni-P-CNT's nanocomposite film plated in the bath with 0.028-g/L CNTs can greatly increase up to 665.9 and 28.9 GPa, respectively, which are approximately four times larger than that of pure nickel. Moreover, the content of CNTs in the Ni-P-CNT's films is measured by an elemental analyzer. Via the electrical resistivity measurement using a four-point probe, it is found that the electrical property of the nanocomposite film can be well characterized using a Maxwell-Wagner model for a two-phase mixture. The performance improvements of the electrothermal microactuator made of the nanocomposite, including device strength and power efficiency, have been proven similar to the actuator made of the Ni-diamond composites by electrolytic plating by Tsai et al, but with more efficiency and higher strength than the Ni-diamond device does.