US5220838A
Expired / Lapsed
US
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Overpressure-protected, differential pressure sensor and method of making the same
Assignee: Schneider Electric Systems USA Inc
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Filing: 1991-03-28
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Granted: 1993-06-22
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Expires: 2011-03-28
Abstract
Abstract An overpressure-protected, differential pressure sensor (37) is formed by depositing diaphragm material (24) over a cavity (23) formed and filled with sacrificial material (22) into a front surface of a substrate. The sacrificial material (22) is then removed to create a free diaphragm. The floor of the cavity (23) defines a first pressure stop to limit the deflection of the diaphragm in response to pressure applied to the top of the diaphragm. A port (33) is created to allow pressure to be applied to the bottom side of the diaphragm (24). An optional second pressure stop, which limits the deflection of the diaphragm in response to pressure applied to the bottom side of the diaphragm, is formed by bonding a cap (35) to standoffs (34) placed around the top of the diaphragm. The standoffs are spaced to allow pressure to be applied to the top of the diaphragm.
Inventors
- 👤 Clifford D. Fung
- 👤 Kevin H.-L. Chau
- 👤 P. Rowe Harris
- 👤 John G. Panagou
- 👤 Gary A. Dahrooge
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 03:27
CPC Classifications
G; G01; G01L; G01L9/00; G01L9/0041; G01L9/0051; G01L9/0052; G01L9/0055; G01L9/0042; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49002; Y10T29/49082; Y10T29/49103; Y10T29/4981; Y10T29/49812; Y10T29/49995; Y10T29/49996
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
124 words
A differential pressure sensor comprising: a silicon substrate having a cavity formed into a top surface of said substrate, wherein the floor of the cavity defines a forward pressure stop; a deformable diaphragm formed of polysilicon material deposited over and spanning the cavity, wherein the deflection of the diaphragm in response to pressure applied to the top side of the diaphragm is limited by the forward pressure stop; means for applying a first fluid pressure to the underside of the diaphragm; and means for applying a second fluid pressure to the top side of the diaphragm; and electrical means for detecting the relative deflection of the diaphragm due to a pressure differential between said first and said second fluid pressure exerted across the diaphragm.
Claim 2
Dependent Claim
124 words
A differential pressure sensor comprising: a silicon substrate having a cavity formed into a top surface of said substrate, wherein the floor of the cavity defines a forward pressure stop; a deformable diaphragm formed of polysilicon material deposited over and spanning the cavity, wherein the deflection of the diaphragm in response to pressure applied to the top side of the diaphragm is limited by the forward pressure stop; means for applying a first fluid pressure to the underside of the diaphragm; and means for applying a second fluid pressure to the top side of the diaphragm; and electrical means for detecting the relative deflection of the diaphragm due to a pressure differential between said first and said second fluid pressure exerted across the diaphragm.
Claim 3
Dependent Claim
53 words
The differential pressure sensor of claim further comprising: standoffs placed about the diaphragm to support a back pressure stop; a cap placed on said standoffs and over the diaphragm to define the back pressure stop for limiting the deflection of the diaphragm in response to pressure applied to the underside of the diaphragm.
Claim 4
Dependent Claim
25 words
The differential pressure sensor of claim 1 wherein said means for applying pressure includes a port formed by etching the back surface of the substrate.
Claim 5
Dependent Claim
32 words
The differential pressure sensor of claim 1 wherein the floor of the cavity is coated with material that prevents said diaphragm from sticking to the floor of the cavity during overpressure conditions.
Claim 6
Dependent Claim
15 words
The differential pressure sensor of claim 4 wherein said coating material is a nitride coating.
Claim 7
Dependent Claim
147 words
A differential pressure sensor comprising: a silicon substrate having a cavity formed into a top surface of said substrate, wherein the floor of the cavity defines a first pressure stop; a deformable diaphragm deposited over the cavity, wherein the deflection of the diaphragm in response to pressure applied to the top side of the diaphragm is limited by the first pressure stop; standoffs placed about the diaphragm to support a second pressure stop; a cap placed on said standoffs and over the diaphragm to define the second pressure stop for limiting the deflection of the diaphragm in response to pressure applied to the underside of the diaphragm; means for applying pressure to the top surface of the diaphragm; means for applying pressure to the underside of the diaphragm; and electrical means for detecting the relative deflection of the diaphragm due to a pressure differential across the diaphragm.
Claim 8
Dependent Claim
147 words
A differential pressure sensor comprising: a silicon substrate having a cavity formed into a top surface of said substrate, wherein the floor of the cavity defines a first pressure stop; a deformable diaphragm deposited over the cavity, wherein the deflection of the diaphragm in response to pressure applied to the top side of the diaphragm is limited by the first pressure stop; standoffs placed about the diaphragm to support a second pressure stop; a cap placed on said standoffs and over the diaphragm to define the second pressure stop for limiting the deflection of the diaphragm in response to pressure applied to the underside of the diaphragm; means for applying pressure to the top surface of the diaphragm; means for applying pressure to the underside of the diaphragm; and electrical means for detecting the relative deflection of the diaphragm due to a pressure differential across the diaphragm.
Claim 9
Dependent Claim
25 words
The differential pressure sensor of claim 6 wherein said means for applying pressure includes a port formed by etching the back surface of the substrate.
Claim 10
Dependent Claim
32 words
The differential pressure sensor of claim 6 wherein the floor of the cavity is coated with material that prevents said diaphragm from sticking to the floor of the cavity during overpressure conditions.
Claim 11
Dependent Claim
15 words
The differential pressure sensor of claim 8 wherein said coating material is an oxide coating.
Claim 12
Dependent Claim
15 words
The differential pressure sensor of claim 8 wherein said coating material is a nitride coating.
Claim 13
Dependent Claim
26 words
The differential pressure sensor of claim 6 wherein the cap is coated with material that prevents the diaphragm from, sticking to the cap during overpressure conditions.
Claim 14
Dependent Claim
22 words
The differential pressure sensor of claim 6 wherein the cap is bonded against said standoffs using boron-doped oxide as a bonding agent.
Claim 15
Dependent Claim
21 words
The differential pressure sensor of claim 6 wherein the cap is bonded against said standoffs using spin-on-glass as a bonding agent.
Claim 16
Dependent Claim
20 words
The differential pressure sensor of claim 6 wherein the cap is bonded against said standoffs using metal to silicon bonds.
Claim 17
Independent Claim
127 words
A method of producing an overpressure-protected differential sensor comprising the steps of: forming a cavity in a top surface of a substrate, wherein said cavity has a preselected depth and shape to define a forward pressure stop; filing the cavity with s acarificial spacer material; depositing a layer of deformable diaphragm material over the top surface of the substrate and sacrificial material; removing substrate material to provide a port for removing said sacrificial spacer material and for applying back pressure to the underside of said diaphragm material; and removing said sacrificial spacer material from the cavity so that the cavity forms said forward pressure stop for limiting deflection of said diaphragm material when pressure applied to the top surface thereof greatly exceeds pressure applied to said port.
Claim 18
Independent Claim
127 words
A method of producing an overpressure-protected differential sensor comprising the steps of: forming a cavity in a top surface of a substrate, wherein said cavity has a preselected depth and shape to define a forward pressure stop; filing the cavity with s acarificial spacer material; depositing a layer of deformable diaphragm material over the top surface of the substrate and sacrificial material; removing substrate material to provide a port for removing said sacrificial spacer material and for applying back pressure to the underside of said diaphragm material; and removing said sacrificial spacer material from the cavity so that the cavity forms said forward pressure stop for limiting deflection of said diaphragm material when pressure applied to the top surface thereof greatly exceeds pressure applied to said port.
Claim 19
Dependent Claim
38 words
The method of producing an overpressure-protected, differential sensor as claimed in claim 15 further including the step of depositing material in the cavity to prevent the diaphragm from sticking to the floor of the cavity during overpressure conditions.
Claim 20
Dependent Claim
50 words
The method of producing an overpressure-protected, differential sensor as claimed in claim 15 further comprising the steps of: depositing standoffs on the top surface of the substrate about the cavity for supporting a back pressure stop; bonding a cap against the standoffs, wherein the cap defines the back pressure stop;
Claim 21
Independent Claim
153 words
A method of producing a bi-directional, overpressure-protected differential sensor comprising the steps of: forming a cavity in a top surface of a substrate, wherein the cavity has preselected depth and shape to define a forward pressure stop; filling the cavity with a sacrificial spacer material; depositing a layer of deformable diaphragm material over the top surface of the substrate and sacrificial material; depositing standoffs on the top surface of the substrate about the cavity for supporting a back pressure stop; bonding a cap against the standoffs, wherein the cap extends over the diaphragm material and defines the back pressure stop; removing substrate material to provide a port for removing said sacrificial spacer material; and removing said sacrificial spacer material from the cavity leaving the diaphragm material suspended over the cavity to bidirectionally deflect in response to differences between pressure applied to said cavity and pressure applied between said cap and the diaphragm material....
Claim 22
Independent Claim
153 words
A method of producing a bi-directional, overpressure-protected differential sensor comprising the steps of: forming a cavity in a top surface of a substrate, wherein the cavity has preselected depth and shape to define a forward pressure stop; filling the cavity with a sacrificial spacer material; depositing a layer of deformable diaphragm material over the top surface of the substrate and sacrificial material; depositing standoffs on the top surface of the substrate about the cavity for supporting a back pressure stop; bonding a cap against the standoffs, wherein the cap extends over the diaphragm material and defines the back pressure stop; removing substrate material to provide a port for removing said sacrificial spacer material; and removing said sacrificial spacer material from the cavity leaving the diaphragm material suspended over the cavity to bidirectionally deflect in response to differences between pressure applied to said cavity and pressure applied between said cap and the diaphragm material....
Claim 23
Dependent Claim
28 words
The method of producing a bi-directional, overpressure-protected, differential sensor as claimed in claim 18 wherein the cap is bonded against the standoffs using spin-on-glass as a bonding agent.
Claim 24
Dependent Claim
29 words
The method of producing a bi-directional, overpressure-protected, differential sensor as claimed in claim 18 wherein the cap is bonded against the standoffs using boron-doped oxide as a bonding agent.
Claim 25
Dependent Claim
27 words
The method of producing a bi-directional, overpressure-protected, differential sensor as claimed in claim 18 wherein the cap is bonded against the standoffs using silicon to metal bonding.
Claim 26
Dependent Claim
33 words
The method of producing a bi-directional, overpressure-protected, differential sensor as claimed in claim 18 wherein the cap is coated with material to prevent the diaphragm from sticking to the cap during overpressure conditions.
Claim 27
Dependent Claim
39 words
The method of producing a bi-directional, overpressure-protected, differential sensor as claimed in claim 44 further including the step of depositing material in the cavity to prevent the diaphragm from sticking to the floor of the cavity during overpressure conditions.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-06-21 | 1996-12-21 | 1997-06-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-06-21 | 2000-12-21 | 2001-06-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-06-21 | 2004-12-21 | 2005-06-22 | $7700.00 | Window Closed / Lapsed |