Micromechanical moisture sensor device and corresponding manufacturing method

• US 10,641,722 B2
• Filed: 04/10/2017
• Issued: 05/05/2020
• Est. Priority Date: 04/28/2016
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Schwille, Matthias Christian
• Primary Examiner(s): Natalini, Jeff W
• Application Number:
  US15/483,319
• Publication Number:
  US 20170315074A1
• Time in Patent Office: 1,121 Days
• CPC Class Codes: B81B 7/0096 by heating
• CPC Class Codes: B81B 7/02 containing distinct electrical or optical devices of particular relevance for their function, e.g. microelectro-mechanical systems [MEMS] B81B7/04 takes precedence
• CPC Class Codes: G01N 27/121 for determining moisture content, e.g. humidity, of the fluid moisture content of the tested material G01N27/048
• CPC Class Codes: G01N 27/225 by using hygroscopic materials
• CPC Class Codes: H10N 99/00 Subject matter not provided for in other groups of this subclass

Abstract

A micromechanical moisture-sensor device and a corresponding manufacturing method. The micromechanical moisture-sensor device is equipped with a first electrode device situated on the substrate; a second electrode device situated on the substrate; an electrical insulation device situated between the first electrode device and the second electrode device which includes a first area, which is in contact with the first electrode device and the second electrode device, and which includes a second area, which is exposed by the first electrode device and the second electrode device; a moisture-sensitive functional layer, which is applied across the first electrode device and the second electrode device and the second area of the insulation device lying between them in such a way that it forms a moisture-sensitive resistive electrical shunt at least in some areas between the first electrode device and the second electrode device.

Claims

1. A micromechanical moisture sensor device, comprising:

a substrate;

a first electrode device situated on the substrate;

a second electrode device situated on the substrate;

an electrical insulation device situated between the first electrode device and the second electrode device, the insulation device including;

a first area which is in contact with the first electrode device,

a second area which is uncovered by the first electrode device and the second electrode device, and

a third area that is in contact with the second electrode device;

a moisture-sensitive functional layer which is applied directly onto the first electrode device, the second electrode device, and the second area of the insulation device lying between them in such a way that the moisture-sensitive functional layer forms a moisture-sensitive resistive electrical shunt at least in some areas between the first electrode device and the second electrode device, wherein the moisture-sensitive functional layer has a uniform thickness on the first electrode device, the second electrode device, and the second area of the insulation device, wherein;

the first electrode device and the second electrode device and the insulation device are vertically stacked on the substrate,

the second electrode device includes an electrode plate and the first electrode device includes a plurality of electrode bars which are situated laterally spaced having an insulation area of the insulation device located between each of them on the electrode plate in such a way that a parallel circuit is formed by a corresponding plurality of moisture-sensitive resistive electrical shunts between the first electrode device and the second electrode device,

the electrode plate includes a top surface having a single continuous planar shape,

the insulation device includes a plurality of insulation bars laterally spaced apart from each other and vertically stacked on top of and in direct contact with the electrode plate on the top surface of the electrode plate, and

each of the electrode bars is stacked on top of and in direct contact with a respective one of the insulation bars.

2. The micromechanical moisture sensor device as recited in claim 1, wherein the first electrode device and the second electrode device are situated laterally spaced on the insulation device.

3. The micromechanical moisture sensor device as recited in claim 1, wherein a heating device for heating the moisture-sensitive functional layer is situated on or in the substrate.

4. The micromechanical moisture sensor device as recited in claim 1, wherein the first electrode device and the second electrode device are connected to a current measuring device via an electrical contact device.

5. The micromechanical moisture sensor device as recited in claim 1, wherein the moisture-sensitive functional layer is a moisture-sensitive oxide that has a thickness in the range 1 nm through 100 nm.

6. The micromechanical moisture sensor device as recited in claim 1, wherein the insulation device is manufactured from thermal silicon oxide.

7. The micromechanical moisture sensor device as recited in claim 1, wherein the first electrode device and the second electrode device are manufactured from polysilicon.

8. The micromechanical moisture sensor as recited in claim 1, wherein the first electrode device, the second electrode device, and the electrical insulation device are stacked on top of one another in such a way that a vertical axis intersects the first electrode, the second electrode, and the electrical insulation device.

9. A method for manufacturing a micromechanical moisture sensor device, comprising:

providing a substrate;

forming a first electrode device on the substrate;

forming a second electrode device on the substrate;

forming an electrical insulation device between the first electrode device and the second electrode device, the insulation device including;

a first area which is in contact with the first electrode device,

a second area which is uncovered by the first electrode device and the second electrode device, and

a third area that is in contact with the second electrode device;

depositing a moisture-sensitive functional layer directly onto the first electrode device, the second electrode device, and the second area of the insulation device lying between them in such a way that the moisture-sensitive functional layer forms a moisture-sensitive resistive electrical shunt at least in some areas between the first electrode device and the second electrode device, wherein the moisture-sensitive functional layer has a uniform thickness on the first electrode device, the second electrode device, and the second area of the insulation device, wherein;

the second electrode device is formed as an electrode plate and the first electrode device is formed as a plurality of electrode bars which are situated laterally spaced having an insulation area of the insulation device located between each of them on the electrode plate in such a way that a parallel circuit is formed by a corresponding plurality of moisture-sensitive resistive electrical shunts between the first electrode device and the second electrode device,

the electrode plate is formed as having a top surface having a single continuous planar shape,

the insulation device is formed as a plurality of insulation bars laterally spaced apart from each other and vertically stacked on top of and in direct contact with the electrode plate on the top surface of the electrode plate, and

each of the electrode bars is stacked on top of and in direct contact with a respective one of the insulation bars.

10. The method as recited in claim 9, wherein the deposition is carried out with the aid of an ALD method in a temperature range between 50°

C. and 500°

C.

11. The method as recited in claim 10, wherein the deposition is carried out with the aid of BDEAS and ozone.

12. The method as recited in claim 9, wherein the moisture-sensitive functional layer is an atomic layer deposition (ALD) oxide layer deposited using bis(diethylamino)silane (BDEAS) and ozone, which has a thickness in the range 1 nm through 100 nm.

13. The method as recited in claim 9, wherein the first electrode device, the second electrode device, and the electrical insulation device are stacked on top of one another in such a way that a vertical axis intersects the first electrode, the second electrode, and the electrical insulation device.