Patent EP0049344A2 successfully refreshed from Google Patents.
EP0049344A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Capacitive pressure transducers and methods of fabricating them
Assignee: International Business Machines Corp
•
Filing: 1981-08-11
•
Granted: —
•
Expires: 2001-08-11
Abstract
Abstract A capacitive pressure transducer comprises an electrically conductive diaphragm (24) of semiconductor material surrounded and supported by a body (20,26) of semiconductor material and a perforated metallic membrane supported by the semiconductor body so that there is a hollow (46) between the diaphragm and the membrane. The diaphragm and the membrane respectively serve as the movable plate and the fixed plate of a capacitor, the capacitance of which varies in dependence on the pressures on opposite sides of the diaphragm. The transducer can be made by normal integrated circuit device fabrication steps and so the transducer and utilization circuitry can be fabricated in the same process into a single integrated semiconductor device.
Inventors
- 👤 Kurt Edward Petersen
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-07 21:09
CPC Classifications
G; G01; G01L; G01L9/00; G01L9/0041; G01L9/0072; G01L9/0073
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
94 words
A capacitive pressure transducer characterised in that it comprises an electrically conductive diaphragm (24) of semiconductor material surrounded and supported by a body (20, 26) of semiconductor material, a perforated electrically conductive membrane (38) so supported by the body of semiconductor material that it is spaced from the diaphragm to form a hollow (46) between the membrane and the diaphragm, the diaphragm and the membrane respectively serving as the movable plate and the fixed plate of a capacitor, the capacitance of which varies in dependence on the pressures on opposite sides of the diaphragm.
Claim 2
Dependent Claim
94 words
A capacitive pressure transducer characterised in that it comprises an electrically conductive diaphragm (24) of semiconductor material surrounded and supported by a body (20, 26) of semiconductor material, a perforated electrically conductive membrane (38) so supported by the body of semiconductor material that it is spaced from the diaphragm to form a hollow (46) between the membrane and the diaphragm, the diaphragm and the membrane respectively serving as the movable plate and the fixed plate of a capacitor, the capacitance of which varies in dependence on the pressures on opposite sides of the diaphragm.
Claim 3
Dependent Claim
38 words
A capacitive pressure transducer as claimed in claim 1, in which the diaphragm and the membrane are electrically connected to circuitry integrated in the semiconductor body, the circuitry being responsive to changes in the capacitance of said capacitor.
Claim 4
Dependent Claim
47 words
A transducer as claimed in claim 1 or claim 2, in which the diaphragm is contiguous with the body and is formed of semiconductor material of opposite conductivity type to that of the body, and in which the conductive membrane is metallic and insulated from the body.
Claim 5
Independent Claim
13 words
A method for fabricating a capacitive pressure transducer comprising the successive steps of:-
Claim 6
Independent Claim
13 words
A method for fabricating a capacitive pressure transducer comprising the successive steps of:-
Claim 7
Dependent Claim
31 words
(1) doping a portion of a semiconductor substrate of one conductivity type material with material of the opposite conductivity type in a region in which the transducer is to be formed;
Claim 8
Dependent Claim
31 words
(1) doping a portion of a semiconductor substrate of one conductivity type material with material of the opposite conductivity type in a region in which the transducer is to be formed;
Claim 9
Dependent Claim
29 words
(2) growing an epitaxial layer of semiconductor material of said one conductivity type over said substrate to provide a structure in which the doped portion is a buried layer;
Claim 10
Dependent Claim
29 words
(2) growing an epitaxial layer of semiconductor material of said one conductivity type over said substrate to provide a structure in which the doped portion is a buried layer;
Claim 11
Dependent Claim
21 words
(3) processing said structure for making an electric connection between said buried layer and the outside surface of said epitaxial layer;
Claim 12
Dependent Claim
21 words
(3) processing said structure for making an electric connection between said buried layer and the outside surface of said epitaxial layer;
Claim 13
Dependent Claim
23 words
(4) depositing an insulating layer on the outside surfaces of said structure in the region in which the transducer is to be formed;
Claim 14
Dependent Claim
23 words
(4) depositing an insulating layer on the outside surfaces of said structure in the region in which the transducer is to be formed;
Claim 15
Dependent Claim
17 words
(5) depositing a layer of metal over said insulating layer which is contiguous with said epitaxial layer;
Claim 16
Dependent Claim
17 words
(5) depositing a layer of metal over said insulating layer which is contiguous with said epitaxial layer;
Claim 17
Dependent Claim
26 words
(6) etching a plurality of apertures through the metal layer and the insulating layer beneath it in the region where said transducer is to be formed;
Claim 18
Dependent Claim
26 words
(6) etching a plurality of apertures through the metal layer and the insulating layer beneath it in the region where said transducer is to be formed;
Claim 19
Dependent Claim
25 words
(7) etching through the insulating layer on the opposite side of the structure to the metal layer to define the extent of said transducer: and
Claim 20
Dependent Claim
25 words
(7) etching through the insulating layer on the opposite side of the structure to the metal layer to define the extent of said transducer: and
Claim 21
Dependent Claim
50 words
(8) etching the structure in an etchant for removing semiconductor material from said epitaxial layer in the region of said apertures and from said substrate in the region defined by the etched-through portion of the insulating layer to leave a diaphragm constituted by the material of the formerly buried layer.
Claim 22
Dependent Claim
50 words
(8) etching the structure in an etchant for removing semiconductor material from said epitaxial layer in the region of said apertures and from said substrate in the region defined by the etched-through portion of the insulating layer to leave a diaphragm constituted by the material of the formerly buried layer.
Claim 23
Dependent Claim
15 words
A method as claimed in claim 4, in which said substrate consists of n-type silicon.
Claim 24
Dependent Claim
68 words
A method as claimed in claim 5, in which the n-type silicon substrate has a major surface lying in the (100) plane; in which said portion of the substrate is doped with boron; in which the insulating layer consists of silicon nitride; in which an anisotropic etchant is used in step (8); and in which substrate side of said structure is subsequently protected by a passivating insulating layer.
Claim 25
Independent Claim
33 words
A method as claimed in any of claims 4 to 6, further comprising forming other semiconductor devices in said substrate to produce an integrated circuit in which the capacitive pressure transducer is integrated.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.