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Process technology for the modular integration of CMOS and polysilicon microstructures

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Abstract

Modular fabrication of polysilicon surface-micromachined structures after completion of a conventional CMOS electronic process is described. Key process steps include tungsten metallization with contact diffusion barriers, LPCVD oxide and nitride passivation of the CMOS, rapid thermal processing for stress-relief annealing of the structural polysilicon film, implementation of a sacrificial spin-on-glass planarization, and the final microstructure release in hydrofluoric acid. Modularity of the process enables independent modification of either the CMOS or the microstructure process sequences. This technology is used in the fabrication of various types of sensors and actuators.

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Authors and Affiliations

  1. Berkeley Sensor & Actuator Center, University of California, 94720-1774, Berkeley, CA, USA

    James M. Bustillo, Gary K. Fedder, Clark T. -C. Nguyen & Roger T. Howe

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  1. James M. Bustillo
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  2. Gary K. Fedder
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  3. Clark T. -C. Nguyen
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  4. Roger T. Howe
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Additional information

The authors thank the U.C. Berkeley Microfabrication Facility staff,with a special thanks to Shenqing Fang for timely CMOS fabrication, as well as Wheling Cheng at the Center for Integrated Systems at Stanford University for assistance with CVD tungsten depositions. The transmission electron micrograph was supplied by Peter Krulevitch. Supercritical drying and phase diagram discussion provided by Greg Mulhern. This project is supported by the California Dept. of Transportation PATH project, ARPA, and the Berkeley Sensor & Actuator Center, an NSF/Industry/University Cooperative Research Center.

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Bustillo, J.M., Fedder, G.K., Nguyen, C.T.C. et al. Process technology for the modular integration of CMOS and polysilicon microstructures. Microsystem Technologies 1, 30–41 (1994). https://doi.org/10.1007/BF01367758

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  • DOI: https://doi.org/10.1007/BF01367758

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