A bulk micromachined inertial measurement unit (MIMU) is presented in this paper. Three single-axis accelerometers and three single-axis gyroscopes were simultaneously fabricated on a silicon wafer using a bulk micromachining process; the wafer is smaller than one square centimeter. In particular, a global area optimization method based on the relationship between the sensitivity and layout area was proposed to determine the layout configuration of the six sensors. The scale factors of the X/Y-axis accelerometer and Z-axis accelerometer are about 213.3 mV/g and 226.9 mV/g, respectively. The scale factors of the X/Y-axis gyroscope and Z-axis gyroscope are about 2.2 mV/o/s and 10.8 mV/o/s, respectively. The bias stability of the X/Y-axis gyroscope and the Z-axis gyroscope are about 2135 deg/h and 80 deg/h, respectively. Finally, the resolutions of X/Y-axis accelerometers, Z-axis accelerometers, X/Y-axis gyroscopes, and Z-axis gyroscopes are 0.0012 g/ √Hz, 0.0011 g/ √Hz, 0.314 °/s/ √Hz, and 0.008 °/s/ √Hz, respectively.
References
[1]
Kourepenis, A.; Connelly, J.; Sitomer, J. Low cost MEMS inertial measurement unit. Proceedings of ION NTM, San Diego, CA, USA, January 26–28, 2004; pp. 246–251.
[2]
John, J.D.; Vinay, T. Novel concept of a single-mass adaptively controlled tri-axial angular rate sensor. IEEE Sens. J？2006, 6, 588–595.
[3]
Nan, C.T. Fabrication and analysis of a micro-machined tri-axis gyroscope. J. Micromech. Microeng？2008, 18, 150–164.
[4]
Nan, C.T.; Chung, Y.; Chih, C.L. Design and dynamics of an innovative micro gyroscope against coupling effects. Microsyst. Technol？2008, 14, 295–306.
Kwon, K.J.; Park, S.K. A bulk-micromachined three-axis accelerometer using silicon direct bonding technology and polysilicon layer. Sens. Actuat. A-Phys？1998, 66, 250–255.
[7]
Junseok, C.; Kulah, H.; Ajafi, K. A monolithic three-axis micro-g micromachined silicon capacitive accelerometer. J. Microelectromech. Syst？2005, 14, 235–242.
[8]
Qu, H.W.; Fang, D.Y.; Xie, H.K. A monolithic CMOS-MEMS 3-axis accelerometer with a low-noise, low-power dual-chopper amplifier. IEEE Sens. J？2008, 8, 1511–1518.
[9]
Allen, J.; Kinney, R.; Sarsfield, J.; Daily, M.; Ellis, J.; Smith, J. Integrated micro electro-mechanical sensor development for inertial applications. Proceedings of IEEE PLANS, Rancho Mirage, CA, USA, April 20–23, 1998; pp. 9–16.
[10]
Hao, L.; Fedder, G.; Carley, L. Integrated multiple-device IMU system with continuous-time sensing circuitry. Proceedings of IEEE International Solid-State Circuits, San Francisco, CA, USA, February 2003; pp. 191–205.
[11]
Yong, Z.; Guizhen, Y.; Jie, F.; Xuesong, L.; Jian, Z.; Yangyuan, W. Post-CMOS process for high-aspect-ratio monolithically integrated single crystal silicon microstructures. Proceedings of Tranducers’05, Seoul, Korea, June 5–9, 2005; pp. 1130–1133.
[12]
Xie, H.K.; Zhu, X.; Gabriel, K.J.; Fedder, G.K. Post-CMOS processing for high-aspect-ratio integrated silicon microstructures. J. Microelectromech. Syst？2002, 11, 93–101.
[13]
Alandry, B.; Dumas, N.; Latorre, L.; Mailly, F.; Nouet, P. A CMOS multi-sensor system for 3D orientation determination. Proceedings of IEEE Computer Society Annual on VLSI, Montpellier, France, April 7–9, 2008; pp. 57–62.
[14]
Xie, H.K.; Fedder, G.K. Fabrication, characterization, and analysis of a DRIE COMS-MEMS gyroscope. IEEE Sens. J？2003, 3, 622–631.
[15]
Qu, H.W.; Xie, H.K. Process development for CMOS-MEMS sensors with robust electrically isolated bulk silicon microstructures. J. Microelectromech. Syst？2007, 16, 1152–1161.
[16]
Ajit, S.M.; Mohammad, F.Z.; Mark, Z.C.; Farrokh, A.Z. A 0.1/HR bias drift electronically matched tuning fork microgyroscope. Proceedings of IEEE MEMS, Tucson, AZ, USA, January 13–17, 2008; pp. 6–9.
[17]
Weinberg, M.S.; Kourepenis, A. Error sources in in-plane silicon tuning-fork MEMS gyroscopes. J. Microelectromech. Syst？2006, 15, 479–491.
[18]
Cardarelli, D. An integrated MEMS inertial measurement unit. Proceedings of IEEE PLNS, Los Angeles, CA, USA, April 15–18, 2002; pp. 314–319.
[19]
Chang, H.L.; Yuan, W.Z.; Cui, J.Q.; Jiang, Q.H.; Zhang, P.; Li, Q.; Yang, F. One Bulk Micromachined Single-Chip Inertial Measurement Unit. Proceedings of IEEE Sensors, Daegu, Korea, October 22–25, 2006; pp. 1485–1488.
[20]
Gottscho, R.A.; Jurgensen, C.W. Microscopic uniformity in plasma etching. J. Vac. Sci. Technol. B？1992, 10, 2133–2147.
[21]
Jansen, H.; De Boer, M.; Wiegerink, R.; Tas, N.; Smulders, E.; Neagu, C.; Elwenspoek, M. RIE lag in high aspect ratio trench etching of silicon. Microelectron. Eng？1997, 35, 45–50.
[22]
Hwang, G.S.; Giapis, K.P. On the origin of the notching effect during etching in uniform high density plasmas. J. Vac. Sci. Technol. B？1997, 15, 70–87.
[23]
Cozma, A.; Puers, B. Characterization of the electrostatic bonding of silicon and pyrex glass. J. Micromech. Microeng？1995, 5, 98–102.
[24]
Srinivasa-Murthy, C.; Wang, D.; Beaudoin, S.P.; Bibby, T.; Holland, K.; Cale, T.S. Stress distribution in chemical mechanical polishing. Thin Solid Films？1997, 308–309, 533–537.
[25]
Innam, L.; Gil, H.Y.; Jungyul, P.K.; Seonho, S.K.; Kukjin, C.B.; Kyo-Il, L. Development and analysis of the vertical capacitive accelerometer. Sens. Actuat. A-Phys？2005, 119, 8–18.
[26]
Junseok, C.; Haluk, K.A.; Khalil, N.F. A hybrid silicon-on-glass (SOG) lateral micro-accelerometer with CMOS readout circuitry. Proceedings of IEEE MEMS, Las Vegas, NV, USA, January 20–24, 2002; pp. 623–626.
[27]
Yazdi, N.; Ayazi, F.; Najafi, K. Micromachined inertial sensors. Proc. IEEE？1998, 86, 1640–1659.
[28]
Yazdi, N.; Najafi, K.; Salian, A.S. A high-sensitivity silicon accelerometer with a folded-electrode structure. J. Microelectromech. Syst？2003, 12, 479–486.
[29]
Selvakumar, A.; Najafi, K. A high-sensitivity z-axis capacitive silicon microaccelerometer with a torsional suspension. J. Microelectromech. Syst？1998, 7, 192–200.
[30]
Lee, I.; Yoon, G.H.; Park, J.; Seok, S.; Chun, K.; Lee, K. Development and analysis of the vertical capacitive accelerometer. Sens. Actuat. A？2005, 119, 8–18.
[31]
Bernstein, J.; Cho, S.; King, A.T.; Kourepenis, A.; Mace, P.; Weinberg, M. A micromachined comb-drive tuning fork rate gyroscope. Proceedings of IEEE MEMS, Fort Lauderdale, FL, USA, February 7–10, 1993; pp. 143–148.
[32]
Chen, Y.; Jiao, J.; Xiong, B.; Che, L.; Li, X.; Wang, Y. A novel tuning fork gyroscope with high Q-factors working at atmospheric pressure. Microsyst. Technol？2005, 11, 111–116.
[33]
Said, E.A.; Kivanc, A.; Tayfun, A. A high-performance silicon-on-insulator MEMS gyroscope operating at atmospheric pressure. Sens. Actuat. A-Phys？2007, 135, 34–42.
[34]
Kim, J.; Park, S.; Kwak, D.; Ko, H.; Cho, D.D. An x-axis single-crystalline silicon microgyroscope fabricated by the extended SBM process. J. Microelectromech. Syst？2005, 14, 444–455.
[35]
Acar, C.; Shkel, A.M. Inherently robust micromachined gyroscopes with 2-DOF Sense-Mode oscillator. J. Microelectromech. Syst？2006, 15, 380–387.
[36]
Yuan, W.Z.; Chang, H.L.; Li, W.J. Application of an optimization methodology for multidisciplinary system design of microgyroscopes. Microsyst. Technol？2006, 12, 315–323.
[37]
Ongkodjojo, A.; Francis, E.H.T. Global optimization and design for microelectromechanical systems devices based on simulated annealing. J. Micromech. Microengineer？2002, 12, 878–897.
[38]
Beeby, S.; Ensell, G.; Kraft, M.; White, N. MEMS Mechanical Sensors, 1st ed ed.; Artech House: Boston, MA, USA/London, UK, 2004; pp. 174–175.
