Sensor element for thermal anemometry

Patent metadata

Field	Value
Publication number	US-10473683-B2
Application number	US-201715482173-A
Country	US
Kind code	B2
Filing date	Apr 7, 2017
Priority date	Apr 19, 2016
Publication date	Nov 12, 2019
Grant date	Nov 12, 2019

Abstract

A sensor element for thermal anemometry includes a semiconductor substrate and a thin-film diaphragm attached to the semiconductor substrate and having a front side and a rear side. A resistive heating element and a temperature-dependent resistor are attached to the front side of the thin-film diaphragm. In the area of the rear side of the thin-film diaphragm, the semiconductor substrate has a first recess. A silicon layer including a recess which merges with the first recess of the semiconductor substrate is located between the thin-film diaphragm and the semiconductor substrate.

First claim

What is claimed is:

1. A sensor element for thermal anemometry, the sensor element comprising:
a semiconductor substrate;
a film diaphragm attached to the semiconductor substrate;
a resistive heating element on a front side of the film diaphragm;
a temperature-dependent resistor on the front side of the film diaphragm;
a silicon layer between the film diaphragm and the semiconductor substrate, wherein a first recess, which is in the silicon layer, merges with a second recess, which is in the semiconductor substrate at a rear side of the film diaphragm;
a first silicon oxide layer between the silicon layer and the semiconductor substrate; and
wherein the film diaphragm includes a second silicon oxide layer formed in one piece with the first silicon oxide layer.

2. The sensor element of claim 1 , wherein the first silicon oxide layer coats the silicon layer.

3. The sensor element of claim 1 , wherein the silicon layer is an epitaxial silicon layer.

4. The sensor element of claim 1 , wherein the first silicon oxide layer is on a side of the silicon layer.

5. A sensor element for thermal anemometry, the sensor element comprising:
a semiconductor substrate;
a film diaphragm attached to the semiconductor substrate;
a resistive heating element on a front side of the film diaphragm;
a temperature-dependent resistor on the front side of the film diaphragm;
a silicon layer between the film diaphragm and the semiconductor substrate, wherein a first recess, which is in the silicon layer, merges with a second recess, which is in the semiconductor substrate at a rear side of the film diaphragm;
in an area of the first recess, a first silicon oxide layer coating the silicon layer; and
wherein the film diaphragm includes a second silicon oxide layer formed in one piece with the first silicon oxide layer.

6. The sensor element of claim 5 , wherein the first silicon oxide layer is between the silicon layer and the semiconductor substrate.

7. An air mass flow meter comprising:
a sensor element for thermal anemometry, the sensor element including:
a semiconductor substrate;
a film diaphragm attached to the semiconductor substrate;
a resistive heating element on a front side of the film diaphragm;
a temperature-dependent resistor on the front side of the film diaphragm;
a silicon layer between the film diaphragm and the semiconductor substrate, wherein a first recess, which is in the silicon layer, merges with a second recess, which is in the semiconductor substrate at a rear side of the film diaphragm; and
a first silicon oxide layer between the silicon layer and the semiconductor substrate;
wherein the film diaphragm includes a second silicon oxide layer formed in one piece with the first silicon oxide layer;

an activation circuit for electrically heating the film diaphragm using the heating element; and
an evaluation circuit for determining a temperature of the film diaphragm using the temperature-dependent resistor.

8. The air mass flow meter of claim 7 , wherein the silicon layer is an epitaxial silicon layer.

Assignees

• Bosch Gmbh Robert

Inventors

• Schoen Florian
• Lemier Christian
• Kramer Torsten

Classifications

• G01F1/692

  Thin-film arrangements · CPC title

• B81B2203/0127

  Diaphragms, i.e. structures separating two media that can control the passage from one medium to another; Membranes, i.e. diaphragms with filtering function · CPC title

• B81B3/0081

  Thermal properties · CPC title

• G01P5/12 Primary

  using variation of resistance of a heated conductor · CPC title

• B81B2201/0278

  Temperature sensors · CPC title