EP0230084A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Blister FET pressure sensor
Assignee: Sentron Vof
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Filing: 1986-12-23
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Granted: —
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Expires: 2006-12-23
Abstract
Abstract A capacitive pressure sensor is presented employing a field effect transistor including a semiconductor substrate (10) having a source region (7) and a drain region (6) with a channel region therebetween. A blister structure (9) is mounted on the substrate and which has walls defining a hermetically sealed cavity (8), exhibiting a low pressure. The cavity overlies the channel region and at least portions of the source and drain regions. The cavity has a flexible roof (14) containing conductive material serving as a flexible capacitor plate which is spaced from and overlies the channel region. Displacement of the flexible roof, due to applied pressure, relative to the channel region varies the transconductance thereof.
Inventors
- 👤 Henrikus Cornelis Geert Ligtenberg
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-06 11:32
CPC Classifications
A; A61; A61B; A61B5/00; A61B5/02; A61B5/021; A61B5/0215; G; G01; G01L; G01L9/00; G01L9/0041; G01L9/0072; G01L9/0073; G01L9/0098; H; H10; H10D; H10D48/00; H10D48/50; A61M; A61M25/00; A61M2025/0001; A61M2025/0002
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
132 words
A capacitive pressure sensor comprising: a field effect transistor including a semiconductor substrate having a source region and a drain region and a channel region between said source and drain regions; a blister structure mounted on said substrate, said blister structure having walls defining a hermetically sealed cavity exhibiting a low pressure less than that of atmospheric, said cavity overlies at least portions of said source and drain regions and the channel region therebetween; and said cavity walls including a flexible roof containing a layer of conductive material serving as a movable capacitor plate which is spaced from and overlies said channel region so as to vary the transconductance thereof as a function of any displacement of said flexible roof relative to said channel region caused by pressure applied to said roof.
Claim 2
Dependent Claim
132 words
A capacitive pressure sensor comprising: a field effect transistor including a semiconductor substrate having a source region and a drain region and a channel region between said source and drain regions; a blister structure mounted on said substrate, said blister structure having walls defining a hermetically sealed cavity exhibiting a low pressure less than that of atmospheric, said cavity overlies at least portions of said source and drain regions and the channel region therebetween; and said cavity walls including a flexible roof containing a layer of conductive material serving as a movable capacitor plate which is spaced from and overlies said channel region so as to vary the transconductance thereof as a function of any displacement of said flexible roof relative to said channel region caused by pressure applied to said roof.
Claim 3
Dependent Claim
40 words
A capacitive pressure sensor as set forth in claim 1, wherein said cavity walls include upstanding side walls and a bottom wall which together with said roof encompass said cavity and define an area overlying said source and drain regions.
Claim 4
Dependent Claim
57 words
A capacitive pressure sensor as set forth in claim 2, wherein said substrate has a first conductive region laterally spaced from said cavity defining side walls and being electrically isolated from said source and drain regions, said first conductive region is electrically connected to said movable capacitor plate and serves as an access for a gate electrode.
Claim 5
Dependent Claim
55 words
A capacitive pressure sensor as set forth in claim 2, wherein said bottom wall is a layer of insulating material, and said side walls and said roof are defined by a lamination including inner and outer layers of insulating material with a layer of conductive material therebetween inclusive of said capacitor plate in said roof.
Claim 6
Dependent Claim
36 words
A capacitive pressure sensor as set forth in claim 4 including blister side walls supporting means in said substrate for supporting saidblister side walls while electrically isolating said conductive material from said source and drain regions.
Claim 7
Dependent Claim
56 words
A capacitive pressure sensor as set forth in claim 5, wherein said substrate is of a first conductivity type and said source and drain regions are of a second conductivity type, said blister side wall supporting means including support regions of said second conductivity type in said substrate and spaced from said source and drain regions.
Claim 8
Dependent Claim
25 words
A capacitive pressure sensor as set forth in claim 6, including channel stopper means interposed between said support regions and said drain and source regions.
Claim 9
Dependent Claim
52 words
A capacitive pressure sensor as set forth in claim 7, wherein said substrate is silicon and said layer of conductive material is polysilicon and said layers of insulating material are silicon dioxide and said cavity is hermetically sealed through annealing in oxygen at a temperature on the order of 1000°C to 1150°C.
Claim 10
Dependent Claim
50 words
A capacitive pressure sensor as set forth in claim 1, including a needle-like tubular housing having a side port aperture therein, means for mounting said substrate within said housing so that said flexible roof of said blister structure faces said aperture so as to be exposed to pressure acting therethrough.
Claim 11
Dependent Claim
53 words
A capacitive pressure sensor as set forth in claim 9, wherein said tubular housing is a catheter tip transducer housing adapted to be fitted to a catheter and being of a size sufficiently small to be inserted into a blood vessel of a living body for measuring blood pressure at a site therein.
Claim 12
Independent Claim
132 words
A method of constructing a capacitive pressure sensor comprising the steps of: providing a semiconductor substrate of a first conductivity type; forming spaced apart drain and source regions of a second conductivity type in said substrate so as to define a channel region therebetween; placing a spacer of silicon dioxide on said substrate so that it overlies said channel region and at least portions of said drain and source regions; applying a layer of polysilicon over said spacer and at least portions of said substrate; etching away said spacer block so as to leave a cavity over said channel region; subjecting the thus defined structure to oxidation at a temperature sufficient for oxygen in the cavity to be consumed to a low pressure, less than atmospheric, resulting in a hermetically sealed cavity.
Claim 13
Independent Claim
132 words
A method of constructing a capacitive pressure sensor comprising the steps of: providing a semiconductor substrate of a first conductivity type; forming spaced apart drain and source regions of a second conductivity type in said substrate so as to define a channel region therebetween; placing a spacer of silicon dioxide on said substrate so that it overlies said channel region and at least portions of said drain and source regions; applying a layer of polysilicon over said spacer and at least portions of said substrate; etching away said spacer block so as to leave a cavity over said channel region; subjecting the thus defined structure to oxidation at a temperature sufficient for oxygen in the cavity to be consumed to a low pressure, less than atmospheric, resulting in a hermetically sealed cavity.
Claim 14
Dependent Claim
27 words
A method as set forth in claim 9, wherein said oxidation step takes place at a temperature sufficient to prevent any water to remain in said cavity.
Claim 15
Dependent Claim
25 words
A method as set forth in claim 10, wherein said oxidation step takes place at a temperature on the order of 1000°C to 1150 °C.
References Cited (Backward Citations)
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