Thin-film temperature sensor and method of making same

Claim 2

A thin-film temperature sensor comprising a capacitor including a tantalum foil, a thin film of anodic tantalum oxide forming a substrate on one side of said foil, a first thin film of metal deposited on said substrate forming a first electrode of said capacitor, a thin layer of dielectric material deposited over said first electrode, a second thin film of metal deposited on said layer of dielectric material, said second film overlapping said first thin film of metal over an area thereof and forming; a second electrode of said capacitor, and a window etched through said foil from the side thereof opposite said one side to expose said substrate over an area which includes the area wherein said first and second thin films of Metal overlap.

Claim 3

A thin-film temperature sensor as defined in claim 1 including an oxide insulation layer over said thin film of dielectric material except over the area of said window.

Claim 4

A thin-film temperature sensor as defined in claim 2 including a polymer coating on the entire surface thereof.

Claim 5

A thin-film temperature sensor as defined in claim 2 wherein said substrate is on said foil uniformly except over a first area remote from said window wherein said foil is exposed and said first thin film of metal is deposited in a continuous film over said area remote from said window for making an electrical connection with said first electrode of said capacitor through said foil, and said second thin film of metal is deposited in a continuous film over said oxide insulation layer to adjacent a second area remote from said window, and wherein an electrical lead is connected to said second thin film of metal at said second area.

Claim 6

A thin-film temperature sensor as defined in claim 3 including an oxide passivation layer underneath said polymer coating on the entire surface opposite said foil except over said area having an electrical lead connected thereto.

Claim 7

A thin-film capacitor for measuring the temperature of fluids, said capacitor being encapsulated in a layer of polymer and comprising a foil of tantalum, said foil having a substrate consisting of a thin film of anodic tantalum oxide on one side of said foil and a first contact area of the foil surface a window through said foil to said substrate over a predetermined area of the substrate, a first capacitor electrode consisting of a continuous thin metallic film over a substantial part of said predetermined area and said first contact area, a dielectric layer over said substrate and said first electrode, an electrical insulation layer over said dielectric layer exclusive of the area over said predetermined area, a second capacitor electrode over said dielectric layer consisting of a thin metallic film over a substantial part of said predetermined area overlapping said first electrode, and over said insulation layer, and including a second contact area, and an electrical lead connected to said second contact area.

Claim 8

A thin-film capacitor for measuring the temperature of fluids, said capacitor being encapsulated in a layer of polymer and comprising a foil of tantalum, said foil having a substrate consisting of a thin film of anodic tantalum oxide on one side of said foil and a first contact area of the foil surface a window through said foil to said substrate over a predetermined area of the substrate, a first capacitor electrode consisting of a continuous thin metallic film over a substantial part of said predetermined area and said first contact area, a dielectric layer over said substrate and said first electrode, an electrical insulation layer over said dielectric layer exclusive of the area over said predetermined area, a second capacitor electrode over said dielectric layer consisting of a thin metallic film over a substantial part of said predetermined area overlapping said first electrode, and over said insulation layer, and including a second contact area, and an electrical lead connected to said second contact area.

Claim 11

A method as defined in claim 7 wherein said step of vapor depositing said dielectric material is followed with a step of annealing the deposited dielectric material before depositing said second film of conductive material.

Claim 12

A method as defined in claim 7 wherein the step of sealing comprises coating the assembly with a polymer on all sides.

Claim 13

A method as defined in claim 7 wherein the step of sealing the assembly comprises applying a film of Al2O3 for a passivation layer over films on said substrate.

Claim 14

A method as defined in claim 10 wherein said step of sealing the assembly with said protective coating includes depositing a film of polymer on all sides.

Claim 15

A method as defined in claim 7 wherein said steP of vapor depositing said dielectric material comprises depositing a layer. of ZrO2. 13 A method as defined in claim 12 which comprises applying a thin film of Al2O3 on each side of said ZrO2.

Claim 16

A method as defined in claim 13 which comprises annealing said layer of dielectric material before depositing said second film of conductive material.

Claim 17

A method as defined in claim 7 which comprises depositing a layer of SiO2 for a protective layer over said layer of dielectric material, except over said predetermined area of said substrate, before depositing second film of conductive material.

Claim 18

A method as defined in claim 15 wherein said step of sealing the assembly with a protective coating includes depositing a film of polymer on all sides.

Claim 19

A method as defined in claim 15 wherein said step of sealing the assembly with said protective coating includes depositing a film of Al2O3 for a passivation layer over films on said substrate.

Claim 20

A method as defined in claim 17 wherein said step of sealing the assembly with said protective coating further includes depositing a film of polymer on all sides.