Microelectromechanical System Inductor Research Articles

Failure mode analysis of MEMS suspended inductors under mechanical shock

Micro-electromechanical system (MEMS) suspended inductors have been widely studied in recent decades because of their excellent radio frequency performance. However, few studies have been performed on the failure analysis of MEMS suspended inductors under mechanical shock. In this study, the failure of MEMS suspended inductors with a planar spiral coil is investigated through analytical and experimental methods. We present a stress and deformation analysis to study the failure mode of the suspended inductors under shock. To verify the theoretical analysis, MEMS inductors are designed and fabricated, and shock tests are carried out. The shock tests show that the failure mode of the MEMS suspended inductors is a fracture that occurs at the ends of the inductor coil, and the test results agree with the theoretical analysis.

Mechanical Response of MEMS Inductor with Auxiliary Pillar under High-g Shock.

Micro-electromechanical system (MEMS) suspended inductors have excellent radio-frequency (RF) performance, but poor mechanical properties. To improve their reliability, auxiliary pillars have been used. However, few studies have been carried out on the response of a suspended inductor with auxiliary pillars under high mechanical shock. In this paper, a theoretical method is proposed that combines a single-degree-of-freedom (SDOF) model and a method for solving statically indeterminate structures. The calculated results obtained by this proposed method were verified by finite-element analysis (ANSYS). The calculated results obtained by the proposed method were found to agree well with the results of ANSYS simulation. Finally, this method was extended to a suspended inductor with double auxiliary pillars. The method proposed in this paper provides a theoretical reference for mechanical performance evaluation and reliability optimization design for MEMS suspended inductors with auxiliary pillars.

Enhancement of 5 GHz on-chip bandpass filter performance by using CMOS-MEMS inductors

We propose the use of microelectromechanical system (MEMS) inductors to enhance the performance of a 5-GHz on-chip bandpass filter. The proposed filter is implemented using the TSMC 0.18 μm one-poly six-metal (1P6M) CMOS process. For reducing substrate loss to improve filter performance, the silicon substrate underlying the filter’s MEMS inductors is removed using the Chip Implementation Center micromachining postprocess. Compared to conventional on-chip CMOS inductors on-silicon substrate, the simulation results obtained using the CMOS-MEMS inductors showed a quality factor improvement of 264.3% at 5.5 GHz. The measured insertion loss of the proposed filter with the CMOS-MEMS inductors is 3.2 dB at 4.7 GHz, and the ripple is 0.6 dB in the passband. The − 3-dB bandwidth ranges from 4.2 to 5.8 GHz. The attenuation is better than − 22 dB for frequencies ranging from 1 to 3.8 GHz and − 25 dB from 6.9 to 10 GHz in the stopband. The shape factor of the filter is 1.97:1 at an attenuation of 25/3 dB. The chip area is very small, and the optimal chip size is 1.3 × 0.75 mm2. The proposed filter could be integrated directly with the silicon base process, namely, CMOS and BiCMOS, for 5-GHz band wireless front-end applications.

Design and Analysis on Symmetric MEMS Inductor

This paper presents the design and analysis of new proposed topology micro-electro-mechanical system (MEMS) inductor. This new symmetric MEMS inductor is designed to reduce the total length of the conductor strip and hence reduce the resistance of the metal tracks. This results significant increases in the quality (Q) factor of the inductor. In this paper, the MEMS inductor is designed using CoventorWare®, which is powerful software for MEMS computer aided design (CAD), modeling and simulation. Results indicate that new symmetric inductor topology has thehighest Q-factor and it hasbeenimproved bytwo times compared to circular inductor. The analysis revealed that area of the symmetric inductor has reduced by37.5% compared to the circular inductor. Result has proved that the reduction of length of the conductor strip has reduced the resistance of the metal tracks and results in a high Q-factor inductor.

Radio Frequency Micro Electro Mechanical Systems Inductor Configurations for Achieving Large Inductance Variations and High Q-factors

To determine a micro electro mechanical systems (MEMS) inductor configuration that gives large inductance variations and high Q-factors, air-suspended MEMS inductor configurations are studied: (a) an inductor with two angularly meandered lines, (b) a solenoid inductor with a pair of movable shields, (c) a planar spiral inductor with a patterned shield of different areas, and (d) a planar spiral inductor with a metallic frame of different sizes. The configuration of (a) is shown to give a large inductance variation of 115%. However, its Q-factor is only about 10, and difficulties in fabrication are also expected. The configuration of (b) could be a reasonable engineering solution. The inductance variation is 67%, and the maximum Q-factor is over 22. The solenoidal inductor configuration is thus considered suitable for realizing an RF MEMS variable inductor with large inductance variations and high Q-factors.

An Interconnecting Technology for RF MEMS Heterogeneous Chip Integration

An interconnecting technology using a Au-Au thermocompressive bond has been successfully developed for microelectromechanical system (MEMS) heterogeneous chip integration in this paper. The Daisy chain and RF transition structures are both designed and fabricated for the electrical characterization of the interconnect scheme. Measured dc contact resistance is about 14 ±5 m¿ for the bonding interface of Ni (1 ¿m)/Au (0.4 ¿m)/Au (0.4 ¿m)/Ni (1 ¿m) with a pad size of 40 ¿m in diameter. The electrical transition between two chips, which have coplanar waveguides (CPWs) and microstrip lines, respectively, can be well interconnected with less than - 15 dB return loss and - 1.8 dB insertion loss up to 50 GHz without implementing complex structure designs and extra impedance matching networks in the transition by employing this technology. Meanwhile, it is found that the mechanical strength for the interconnecting bond can be as large as 100 MPa. A low-power RF low-noise amplifier has been successfully designed, fabricated, and utilized in this paper to demonstrate the feasibility of the interconnecting technology for RF MEMS heterogeneous chip integration by integrating a Taiwan Semiconductor Manufacturing Corporation 0.18-¿m RF complimentary metal-oxide-semiconductor chip with a silicon carrier, where high <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Q</i> MEMS inductors are fabricated and utilized for good circuit performance in terms of excellent impedance matching, power gain, and gain flatness.

Fully integrated low phase-noise VCOs with on-chip MEMS inductors

We present fully integrated high-performance voltage-controlled oscillators (VCOs) with on-chip microelectromechanical system (MEMS) inductors for the first time. MEMS inductors have been realized from the unique CMOS-compatible MEMS process that we have developed to provide suspended thick metal structures for high-quality (Q) factors. Fully integrated CMOS VCOs have been fabricated by monolithically integrating these MEMS inductors on the top of the CMOS active circuits realized by the TSMC 0.18-/spl mu/m mixed-mode CMOS process. Low phase noise has been achieved as -124 and -117 dBc/Hz at 300-kHz offset from carrier frequencies of 1 and 2.6 GHz, respectively, in the fabricated single-chip VCOs.