Measuring and testing – Fluid pressure gauge – Diaphragm
Patent
1992-10-05
1994-10-25
Woodiel, Donald
Measuring and testing
Fluid pressure gauge
Diaphragm
338 4, G01L 708, G01L 906
Patent
active
053578074
ABSTRACT:
Microminiature pressure transducers are formed on semiconductor substrates such as silicon and include a membrane which spans a cavity over the substrate, with the membrane being mounted to and sealed to the substrate at the peripheral edges of the membrane. The bottom of the cavity forms an overpressure stop to prevent over deflections of the membrane toward the substrate. An overpressure stop formed as a bridge of a material such as nickel extends above the membrane and is spaced therefrom to allow the membrane to deflect freely under normal pressure situations but prevent over deflections. The thickness of the polysilicon membrane and the spacing between the membrane and the overpressure stops is preferably in the range of 10 micrometers or less, and typically in the range of one micrometer. The overpressure stop bridge is formed utilizing deep X-ray lithography to form a well-defined bridge structure. The gap between the membrane and the bottom surface of the bridge is established with a sacrificial layer, such as a polyimide film, which dissolves in a solvent. The transducer is formed utilizing processing techniques which do not affect the performance of the membrane as a pressure sensor and which allow the substrate to have further micromechanical or microelectronic devices formed thereon.
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PiRL: Polymide Release Layer, Brochure from Brewer Science, Inc.
Christensen Todd R.
Guckel Henry
Wisconsin Alumni Research Foundation
Woodiel Donald
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