Thin film platinum resistance thermometer with high temperature diffusion barrier
AssigneeRosemount Inc.
InventorsFred C. Sittler, Adrian C. Toy
Life of this patent
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Abstract
A thin film platinum resistance thermometer capable of operation at elevated temperatures includes a benign dielectric layer covering the thin film platinum resistance temperature sensing element and a barrier layer overlying the dielectric layer. The barrier layer, which is preferrably titanium dioxide, resists diffusion of contaminants which would alter the electrical characteristics of the sensing element, while permitting diffusion of oxygen through the barrier layer.
Claims26
A temperature sensor comprising:
- an electrically insulating substrate;
- a resistance temperature sensing element formed of platinum on a first surface of the substrate;
- a benign dielectric layer covering the temperature sensing element;
- and
- a barrier layer overlying the dielectric layer which resists diffusion of contaminants into the platinum while permitting diffusion of oxygen through the barrier layer such that the platinum is protected from contamination.
A protective coating for preventing degradation at elevated temperatures which exceed about 400.degree. C., of electrical characteristics of a resistance temperature sensing element formed of platinum, the protective coating comprising:
- a benign dielectric layer formed of a material substantially free of alkaline metal oxides covering a surface of the resistance temperature sensing element;
- and
- a barrier layer covering the dielectric layer, the barrier layer being formed of a material which, at the elevated temperatures, resists diffusion therethrough of contaminants into the resistance temperature sensing element which would alter the electrical characteristics of the resistance temperature sensing element.
A protective coating for preventing degradation at elevated temperatures which exceed about 400.degree. C., of electrical characteristics of a resistance temperature sensing element formed of platinum, the protective coating comprising:
- a benign dielectric layer covering a surface of the resistance temperature sensing element;
- and
- a barrier layer covering the dielectric layer, the barrier layer being formed of a material which, at the elevated temperatures, resists diffusion therethrough of contaminants into the platinum which would alter the electrical charateristics of the resistance temperature sensing element, wherein the barrier layer is titanium dioxide.
A method of forming a thin film resistance temperature sensor, the method comprising;
- forming a thin film platinum resistance element on a substrate;
- covering the resistance element with a first layer of a benign dielectric material;
- and
- forming, over the first layer, a second layer of a selective barrier material which resists diffusion therethrough of contaminants which would alter electrical characteristics of the resistance element while permitting diffusion of oxygen therethrough.
Dependencies are inferred from the claim text.