US4881410A — Ultraminiature pressure sensor and method of maki…

Claim 1

Independent Claim 69 words

An ultraminiature solid-state capacitive pressure transducer which includes a parallel plate capacitor, comprising: an integrally formed structure made from single-crystal material and having a diaphragm and a rim extending about a substantial portion of the periphery of the diaphragm, the structure having at least two dimensions orthogonal to one another of less than one millimeter, and the diaphragm constituting a plane supporting one plate of the parallel plate capacitor.

Claim 2

Dependent Claim 69 words

An ultraminiature solid-state capacitive pressure transducer which includes a parallel plate capacitor, comprising: an integrally formed structure made from single-crystal material and having a diaphragm and a rim extending about a substantial portion of the periphery of the diaphragm, the structure having at least two dimensions orthogonal to one another of less than one millimeter, and the diaphragm constituting a plane supporting one plate of the parallel plate capacitor.

Claim 3

Dependent Claim 23 words

A transducers as in claim 1, further comprising: a glass plate electrostatically bonded to at least part of the rim of the structure.

Claim 4

Dependent Claim 43 words

A transducer as in claim 1, wherein: the single-crystal material is silicon, and the rim and diaphragm are heavily impregnated with at least first material alters an etching characteristic thereof in comparison to single-crystal material which contains substantially less of such first material.

Claim 5

Dependent Claim 26 words

A transducer as in claim 3, wherein: the first material is an impurity dopant selected from the group of dopants including n-type materials and p-type materials.

Claim 6

Dependent Claim 12 words

A transducer as in claim 3, wherein the first material is boron.

Claim 7

Dependent Claim 45 words

A transducer as in claim 1, wherein the rim and diaphragm are made from a common wafer of single-crystal material and the nominal width of the rim is at least three times smaller than the nominal thickness of the wafer from which it is made.

Claim 8

Dependent Claim 34 words

A transducer as in claim 6 wherein the nominal thickness of the rim is no more than about 80 microns, and the nominal height of the rim is no more than about 12 microns.

Claim 9

Dependent Claim 24 words

A transducer as in claim 1, wherein the nominal thickness of the single-crystal material of the diaphragm is no more than about two microns.

Claim 10

Dependent Claim 146 words

A transducer as in claim 1 having first and second electrically conductive parallel plates which form the parallel plate capacitor, whose capacitance is adjustable by a change in pressure upon at least one of the plates, further comprising an insulating nonflexible support substrate having an electrically conductive plate formed on a first side thereof, which constitutes the first parallel plate, and wherein: the diaphragm of the integrally formed structure constitutes the second parallel plate, the rim of the integrally formed structure is bonded to the first side of the support substrate and at least substantially surrounds the perimeter of the first parallel plate, the nominal thickness of the rim is no more than about 80 microns and the nominal height of the rim is no more than about 12 microns, and the nominal gap between the first and second parallel plates is less than five microns.

Claim 11

Dependent Claim 36 words

A transducer as in claim 9, wherein the overall size of the diaphragm measured in two orthogonal directions along the plane of the diaphragm is no more than about five hundred microns in each such direction.

Claim 12

Dependent Claim 157 words

A transducer as in claim 1, having first and second electrically conductive parallel plates which form the capacitor whose capacitance is adjustable by a change in pressure upon at least one of the plates, further comprising: a thin composite dielectric layer formed on one side of the diaphragm; and an insulating nonflexible support substrate having an electrically conductive plate formed on a first side thereof, which constitutes the first parallel plate, and wherein the diaphragm of the integrally formed structure constitutes the second parallel plate, the rim of the integrally formed structure is bonded to the first side of the support substrate and at least substantially surrounds the perimeter of the first parallel plate, the composite dielectric layer is on the side of the diaphragm facing the first parallel plate, and is formed of at least first and second sublayers, the first sublayer including a thermally grown oxide and the second sublayer including a deposited silicon nitride.

Claim 13

Dependent Claim 46 words

A transducer as in claim 1, wherein the diaphragm of the integrally formed structure is rectangularly shaped, is centrally located in and surrounded by the rim, and has an average thickness which is at least a few times thinner than the average thickness of the rim.

Claim 14

Dependent Claim 105 words

A solid-state capacitive pressure transducer including a parallel plate capacitor therein, comprising: an integrally formed structure made from single-crystal silicon semiconductor material and having a diaphragm and a rim that extends at least around a substantial portion of the periphery of the diaphragm, the diaphragm and rim being heavily impregnated with at least a first material which alters an etching characteristic thereof in comparison to single-crystal material which is identical to the heavily impregnated material of the diaphragm and rim except for containing substantially less of such first material, and wherein the diaphragm constitutes a supporting plane of one plate of the parallel plate capacitor.

Claim 15

Dependent Claim 105 words

A solid-state capacitive pressure transducer including a parallel plate capacitor therein, comprising: an integrally formed structure made from single-crystal silicon semiconductor material and having a diaphragm and a rim that extends at least around a substantial portion of the periphery of the diaphragm, the diaphragm and rim being heavily impregnated with at least a first material which alters an etching characteristic thereof in comparison to single-crystal material which is identical to the heavily impregnated material of the diaphragm and rim except for containing substantially less of such first material, and wherein the diaphragm constitutes a supporting plane of one plate of the parallel plate capacitor.

Claim 16

Dependent Claim 40 words

A transducer as in claim 13, further comprising: a glass plate electrostatically bonded to a generally flat surface of the rim, such that the diaphragm is generally parallel to and spaced closely to but remains apart from the glass plate.

Claim 17

Dependent Claim 26 words

A transducer as in claim 13, wherein the first material is an impurity dopant selected from the group of dopants including n-type materials and p-type materials.

Claim 18

Dependent Claim 94 words

A transducer as in claim 13, in which the transducer is part of a pressure sensor, further comprising: an insulating plate bonded on one side thereof to at least part of the rim of the integrally formed structure, a thin electrically conductive pad located on the side of the insulating plate bonded to at least part of the rim, the conductive pad being spaced apart from and generally parallel to the diaphragm and forming a stationary plate of the capacitor of the transducer, with the diaphragm forming a flexible second plate of the capacitor.

Claim 19

Dependent Claim 166 words

A transducer including a pressure-adjustable parallel plate capacitor, comprising: a first electrically conductive plate; and an integrally formed structure made from single-crystal silicon semiconductor material and having a diaphragm and a rim that extend entirely around the periphery of the diaphragm and mechanically supports the diaphragm in a nominal position parallel to and at a predetermined nominal distance from the first plate, the diaphragm and rim being electrically conductive and heavily impregnated with at least a first material which alters an etching characteristic thereof in comparison to single-crystal material which is identical to the heavily impregnated material of the diaphragm and rim except for containing substantially less of such first material, the diaphragm constituting a second electrically conductive plate, and being sufficiently thin relative to its overall size to allow it to respond to a mechanical force applied which is thereto in the form of changing pressure in a range designed to be measured by said transducer, thereby changing the capacitance of the parallel place capacitor.

Claim 20

Dependent Claim 166 words

A transducer including a pressure-adjustable parallel plate capacitor, comprising: a first electrically conductive plate; and an integrally formed structure made from single-crystal silicon semiconductor material and having a diaphragm and a rim that extend entirely around the periphery of the diaphragm and mechanically supports the diaphragm in a nominal position parallel to and at a predetermined nominal distance from the first plate, the diaphragm and rim being electrically conductive and heavily impregnated with at least a first material which alters an etching characteristic thereof in comparison to single-crystal material which is identical to the heavily impregnated material of the diaphragm and rim except for containing substantially less of such first material, the diaphragm constituting a second electrically conductive plate, and being sufficiently thin relative to its overall size to allow it to respond to a mechanical force applied which is thereto in the form of changing pressure in a range designed to be measured by said transducer, thereby changing the capacitance of the parallel place capacitor.

Claim 21

Dependent Claim 45 words

A transducer as in claim 17, wherein the rim and diaphragm are formed from a single wafer of single-crystal material and the nominal width of the rim is at least three times smaller than the nominal thickness of the wafer from which it is made.

Claim 22

Dependent Claim 34 words

A transducer as in claim 18 wherein the nominal thickness of the rim is no more than about 80 microns, and the nominal height of the rim is no more than about 12 microns.

Claim 23

Dependent Claim 24 words

A transducer as in claim 18, wherein the nominal thickness of the single-crystal material of the diaphragm is no more than about two microns.

Claim 24

Dependent Claim 23 words

A transducer as in claim 18, wherein the nominal predetermined distance between the first and second parallel plates is less than five microns.

Claim 25

Dependent Claim 86 words

A transducer as in claim 18, further comprising: a support substrate having least one substantially flat surface on a first side thereof, with the first electrically conductive plate formed on the first side of the substrate, and a conductive trace formed on the first side of the substrate adjacent to and electrically isolated from the first conductive plate, and wherein the rim extends at least around a substantial portion of the periphery of the diaphragm and the rim is in electrical contact with the conductive trace.

Claim 26

Dependent Claim 37 words

A transducer as in claim 22, wherein the support substrate: (1) is configured as an elongated rectangular slab, (2) is no more than about one millimeter long, and (3) is no more than about one-half millimeter wide.

Claim 27

Dependent Claim 28 words

A transducer as in claim 22, wherein the support substrate is a glass material having a coefficient of thermal expansion closely matched to that of single-crystal semiconductor material.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1992-11-20	1993-05-22	1993-11-21	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1996-11-20	1997-05-22	1997-11-21	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2000-11-20	2001-05-22	2001-11-21	$7700.00	Window Closed / Lapsed

Ultraminiature pressure sensor and method of making same

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