Epitaxial Poly Si Surface Micromachining

Masayoshi Esashi,

Masayoshi Esashi

Tohoku University, Micro System Integration Center (μ SIC), 519-1176 Aramaki-Aza-Aoba, Aoba-ku, Sendai, 980-0845 Japan

Search for more papers by this author

Masayoshi Esashi,

Masayoshi Esashi

Tohoku University, Micro System Integration Center (μ SIC), 519-1176 Aramaki-Aza-Aoba, Aoba-ku, Sendai, 980-0845 Japan

Search for more papers by this author

Book Editor(s):Masayoshi Esashi,

Masayoshi Esashi

Search for more papers by this author

First published: 23 April 2021

https://doi.org/10.1002/9783527823239.ch4

Summary

Epi-poly Si (epitaxial poly Si) was developed in Fraunhofer Institute for Silicon Technology in Germany and Uppsala University in Sweden. The thick-doped epi-poly Si is suitable especially for making capacitive sensors with comb structures. Buried diffusion layer is formed for electrical interconnection between the micro electro mechanical system (MEMS) accelerometer and the circuit. Doping of the epi-poly Si is carried out by ion implantation. The circuit is protected by a passivation layer and the epi-poly Si is patterned using deep reactive ion etching. MEMS sensors used in smartphones and other microsystems have been fabricated with the epi-poly Si. The MEMS by epi-poly Si are used for SiP MEMS by connecting with circuit chips. The application-specific integrated circuit chip and the MEMS chip are connected by wire bonding on a substrate and molded with resin.

References

Kirsten, M., Wenk, B., Ericson, F., and Schweitz, J.A. (1995). Deposition of thick doped polysilicon films with low stress in an epitaxial reactor for surface micromachining applications. Thin Solid Films 259 (2): 181–187.
10.1016/0040-6090(94)06449-0
CAS Web of Science® Google Scholar
Lange, P., Kirsten, M., Riethmüller, W. et al. (1996). Thick polycrystalline silicon for surface-micromechanical applications: deposition, structuring and mechanical characterization. Sens. Actuat. A 54: 674–678.
10.1016/S0924-4247(97)80036-2
CAS Web of Science® Google Scholar
Suzuki, Y., Totsu, K., Watanabe, H. et al. (2012). Low-stress epitaxial polysilicon process for micromirror devices. The 29th Symposium on Sensors, Micromachines and Applied Systems, SP2-7, Kitakyushu City, Japan (22–24 October 2012), 548–553.
Google Scholar
Offenberg, M., Lärmer, F., Elsner, B. et al. (1995). Novel process for a monolithic integrated accelerometer. The Eighth International Conference on Solid State Sensors and Actuators, and Eurosensors IX (Transducers'95 Eurosensors IX), Stockholm, Sweden (25–29 June 1995), 589–592.
Google Scholar
Lutz, M., Golderer, W., Gerstenmeier, J. et al. (1997). A precision yaw rate sensor in silicon micromachining. 1997 International Conference on Solid-State Sensors and Actuators (Transducers'97), Chicago, USA (16–19 June 1997), 847–850.
Google Scholar
Candler, N., Park, W.-T., Li, H. et al. (2003). Single wafer encapsulation of MEMS Devices. IEEE Trans. Adv. Packaging 26 (3): 227–232.
10.1109/TADVP.2003.818062
CAS Web of Science® Google Scholar
Langfelder, G., Longoni, A.F., Tocchio, A., and Lasalandra, E. (2011). MEMS motion sensors based on the variations of the fringe capacitances. IEEE Sens. J. 11 (4): 1069–1077.
10.1109/JSEN.2010.2078499
Web of Science® Google Scholar
Prandl, L., Caminada, C., Coronato, L. et al. (2011). A low-power 3-axis digital-output MEMS gyroscope with single drive and multiplexed angular rate readout. 2011 IEEE International Solid-State Circuit Conference (ISSCC 2011), San Francisco, USA (20–24 February 2011), 104–105.
Google Scholar
Classen, J., Reinmuth, J., Kälberer, A. et al. (2017). Advanced surface micromachining process – a first step towards 3D MEMS. The 30th IEEE International Conference on Micro Electro Mechanical Systems (MEMS '17), Las Vegas, USA (22–26 January 2017), 314–316.
Google Scholar

3D and Circuit Integration of MEMS