Analysis and wafer-level design of a high-order silicon vibration isolator for resonating MEMS devices

This paper presents the analysis and preliminary design, fabrication, and measurement for mechanical vibration-isolation platforms especially designed for resonating MEMS devices including gyroscopes. Important parameters for designing isolation platforms are specified and the first platform (in designs with cascaded multiple platforms) is crucial for improving vibration-isolation performance and minimizing side-effects on integrated gyroscopes. This isolation platform, made from a thick silicon wafer substrate for an environment-resistant MEMS package, incorporates the functionalities of a previous design including vacuum packaging and thermal resistance with no additional resources. This platform consists of platform mass, isolation beams, vertical feedthroughs, and bonding pads. Two isolation platform designs follow from two isolation beam designs: lateral clamped?clamped beams and vertical torsion beams. The beams function simultaneously as mechanical springs and electrical interconnects. The vibration-isolation platform can yield a multi-dimensional, high-order mechanical low pass filter. The isolation platform possesses eight interconnects within a 12.2 ? 12.2 mm2 footprint. The contact resistance ranges from 4?11 ? depending on the beam design. Vibration measurements using a laser-Doppler vibrometer demonstrate that the lateral vibration-isolation platform suppresses external vibration having frequencies exceeding 2.1 kHz.

[1]  Leonard Meirovitch,et al.  Elements Of Vibration Analysis , 1986 .

[2]  Chen Chen,et al.  Active Vibration Control and Isolation for Micromachined Devices , 2009 .

[3]  Byeungleul Lee,et al.  MEMS-based angular rate sensors , 2004, Proceedings of IEEE Sensors, 2004..

[4]  A.A. Trusov,et al.  Multi-Degree of Freedom Tuning Fork Gyroscope Demonstrating Shock Rejection , 2007, 2007 IEEE Sensors.

[5]  Sang Won Yoon,et al.  Vibration Isolation and Shock Protection for MEMS. , 2009 .

[6]  K. Najafi,et al.  Nickel-Tin Transient Liquid Phase (TLP) Wafer Bonding for MEMS Vacuum Packaging , 2007, TRANSDUCERS 2007 - 2007 International Solid-State Sensors, Actuators and Microsystems Conference.

[7]  K. Najafi,et al.  Fabrication of vertical comb electrodes using selective anodic bonding , 2007, 2007 IEEE 20th International Conference on Micro Electro Mechanical Systems (MEMS).

[8]  K. Najafi,et al.  Gold-indium Transient Liquid Phase (TLP) wafer bonding for MEMS vacuum packaging , 2008, 2008 IEEE 21st International Conference on Micro Electro Mechanical Systems.

[9]  Manuel Collet,et al.  Active isolation of electronic micro-components with piezoelectrically transduced silicon MEMS devices , 2007 .

[10]  J.R. Reid,et al.  A micromachined vibration isolation system for reducing the vibration sensitivity of surface transverse wave resonators , 1998, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[11]  F. Ayazi,et al.  High Performance Matched-Mode Tuning Fork Gyroscope , 2006, 19th IEEE International Conference on Micro Electro Mechanical Systems.

[12]  J. Judy,et al.  Shock resistance of ferromagnetic micromechanical magnetometers , 2003 .

[13]  S. Sherman,et al.  Single-chip surface micromachined integrated gyroscope with 50°/h Allan deviation , 2002, IEEE J. Solid State Circuits.

[14]  George T. Flowers,et al.  Micromachined Vibration Isolation Filters to Enhance Packaging for Mechanically Harsh Environments , 2005 .

[15]  F. Ayazi,et al.  Sub-Micro-Gravity In-Plane Accelerometers With Reduced Capacitive Gaps and Extra Seismic Mass , 2007, Journal of Microelectromechanical Systems.

[16]  George T. Flowers,et al.  Vibration isolation of MEMS sensors for aerospace applications , 2002 .

[17]  S. An,et al.  Dual-axis microgyroscope with closed-loop detection , 1999 .

[18]  Sang Won Yoon,et al.  Vibration Sensitivity of MEMS Tuning Fork Gyroscopes , 2007, 2007 IEEE Sensors.

[19]  Khalil Najafi,et al.  A Generic Environment-Resistant Packaging Technology for MEMS , 2007, TRANSDUCERS 2007 - 2007 International Solid-State Sensors, Actuators and Microsystems Conference.

[20]  Dmitry V. Balandin,et al.  Optimal protection from impact, shock and vibration , 2001 .

[21]  T. Braman,et al.  Designing Vibration and Shock Isolation Systems for Micro Electrical Machined Based Inertial Measurement Units , 2006, 2006 IEEE/ION Position, Location, And Navigation Symposium.

[22]  Jongpal Kim,et al.  An x-axis single-crystalline silicon microgyroscope fabricated by the extended SBM process , 2005, Journal of Microelectromechanical Systems.