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Proceedings Paper

Silicon surface micromachining of a deep vacuum cavity structure and its application to a microflow sensor
Author(s): Chi-Hoon Jun; Chang-Auck Choi; Won-Ick Jang; Youn Tae Kim
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Paper Abstract

Main interests for MEMS devices are to reduce thermal, dielectric and magnetic loss in active areas due to a substrate and an air medium. For this purpose, deep vacuum cavity structures with planarized stacked membranes were fabricated by the DECTOR process based on silicon surface micromachining. We discuss details of the developed process, especially the effects of a Si trench geometry, post- annealing of the poly-Si layer and HF release conditions on completion of the vacuum structure. To identify validity of the proposed microstructures, thermal microflow sensors having an n+-doped heater and two n+- /p+-doped thermopiles with poly-Si lines were implemented on the various cavity structures of 100 by 100 by 6.2 micrometers 3 using additional CMOS batch processing. The heating efficiency of the sensor on the vacuum cavity is increased by a factor of 5.8 and 1.7 compared to the structures with residual oxides and the air cavity, respectively. It is also found that the sensitivity using the downstream thermopile of 2.5 M(Omega) , 1.53 by 10-1 mV/(m/s)/mW under 10 mW input power, is about ten and three times higher than corresponding values with residual oxides and the air cavity. Therefore, the configuration employing the deep vacuum cavity structure has advantages of low power consumption and the high sensitivity. These results support versatile MEMS applications.

Paper Details

Date Published: 25 August 2000
PDF: 8 pages
Proc. SPIE 4174, Micromachining and Microfabrication Process Technology VI, (25 August 2000); doi: 10.1117/12.396427
Show Author Affiliations
Chi-Hoon Jun, Electronics and Telecommunications Research Institute (South Korea)
Chang-Auck Choi, Electronics and Telecommunications Research Institute (South Korea)
Won-Ick Jang, Electronics and Telecommunications Research Institute (South Korea)
Youn Tae Kim, Electronics and Telecommunications Research Institute (South Korea)


Published in SPIE Proceedings Vol. 4174:
Micromachining and Microfabrication Process Technology VI
Jean Michel Karam; John A. Yasaitis, Editor(s)

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