Wafer arrangement for gas sensor

Patent metadata

Field	Value
Publication number	US-2020355602-A1
Application number	US-202016944279-A
Country	US
Kind code	A1
Filing date	Jul 31, 2020
Priority date	Mar 27, 2015
Publication date	Nov 12, 2020
Grant date	—

Abstract

A gas sensor includes a multi-wafer stack of a plurality of layers and a measurement chamber. The plurality of layers includes a first layer comprising a sensor element that has a microelectromechanical system (MEMS) membrane; and a second layer comprising an emitter element configured to emit electromagnetic radiation. The measurement chamber is interposed between the first layer and the second layer. The measurement chamber is configured to receive a measurement gas and further receive the electromagnetic radiation emitted by the emitter element as the electromagnetic radiation travels along a radiation path from a first end of the measurement chamber to a second end of the measurement chamber that is opposite to the first end.

First claim

What is claimed is:

1 . A gas sensor, comprising:
a multi-wafer stack of a plurality of layers, wherein the plurality of layers comprise:
a first layer comprising a sensor element that has a microelectromechanical system (MEMS) membrane; and
a second layer comprising an emitter element configured to emit electromagnetic radiation; and
a measurement chamber interposed between the first layer and the second layer, the measurement chamber being configured to receive a measurement gas and further receive the electromagnetic radiation emitted by the emitter element as the electromagnetic radiation travels along a radiation path from a first end of the measurement chamber to a second end of the measurement chamber that is opposite to the first end.

2 . The gas sensor of claim 1 , further comprising:
a spacer structure defining the measurement chamber, wherein the spacer structure is mechanically coupled to the first layer at the first end of the measurement chamber and mechanically coupled to the second layer at the second end of the measurement chamber.

3 . The gas sensor of claim 2 , wherein the spacer structure comprise at least one of the plurality of layers of the multi-wafer stack.

4 . The gas sensor of claim 1 , wherein the plurality of layers further comprise:
a third layer coupled to the first layer, wherein the first layer comprises a first cavity and the third layer comprises a second cavity that is conjoined with the first cavity to form a pressure equalizing chamber, wherein the MEMS membrane is interposed between the measurement chamber and the pressure equalizing chamber.

5 . The gas sensor of claim 4 , wherein the pressure equalizing chamber is filled with a protective gas.

6 . The gas sensor of claim 5 , wherein the pressure equalizing chamber is sealed from the measurement chamber by the MEMS membrane.

7 . The gas sensor of claim 4 , wherein the MEMS membrane includes an opening that connects the measurement chamber to the pressure equalizing chamber.

8 . The gas sensor of claim 1 , wherein the plurality of layers further comprise:
a third layer coupled to the second layer, wherein the second layer comprises a first cavity and the third layer comprises a second cavity that is conjoined with the first cavity to form an enclosed hollow space.

9 . The gas sensor of claim 8 , wherein the emitter element is interposed between the measurement chamber and the enclosed hollow space.

10 . The gas sensor of claim 9 , wherein the enclosed hollow space is filled with a protective gas.

11 . The gas sensor of claim 1 , wherein the plurality of layers further comprise:
a third layer coupled to the first layer, wherein the first layer comprises a first cavity and the third layer comprises a second cavity that is conjoined with the first cavity to form a pressure equalizing chamber, wherein the MEMS membrane is interposed between the measurement chamber and the pressure equalizing chamber; and a fourth layer coupled to the second layer, wherein the second layer comprises a third cavity and the fourth layer comprises a fourth cavity that is conjoined with the third cavity to form an enclosed hollow space.

12 . The gas sensor of claim 11 , wherein the emitter element is interposed between the measurement chamber and the enclosed hollow space.

13 . The gas sensor of claim 11 , wherein the pressure equalizing chamber is sealed from the measurement chamber by the MEMS membrane.

14 . The gas sensor of claim 11 , wherein the MEMS membrane includes an opening that connects the measurement chamber to the pressure equalizing chamber.

15 . The gas sensor of claim 1 , wherein the measurement gas converts the electromagnetic radiation into a photoacoustic signal, and the sensor element is configured to measure the photoacoustic signal by detecting deflections of the MEMS membrane.

16 . The gas sensor of claim 1 , wherein the MEMS membrane is configured to have a deflection which is dependent on an energy of the electromagnetic radiation.

17 . The gas sensor of claim 1 , wherein the emitter element is configured to emit the electromagnetic radiation in a pulsating manner with a frequency that is greater than 0.1 Hz.

18 . A gas sensor, comprising:
a wafer arrangement comprising:
a first substrate comprising:
a first portion that includes a sensor element that includes a microelectromechanical system (MEMS) membrane; and
a second portion laterally arranged with respect to the first portion, wherein the second portion includes an emitter element configured to emit electromagnetic radiation toward the MEMS membrane on a radiation path;

a measurement chamber configured to contain a measurement gas, wherein the measurement chamber is in the radiation path between the emitter element and the MEMS membrane; and a housing arranged over the first portion and the second portion of the first substrate and defines the measurement chamber, wherein the housing is configured to receive the electromagnetic radiation from the emitter element and redirect the electromagnetic radiation towards the sensor element.

19 . The gas sensor of claim 1 , wherein the wafer arrangement comprises:
a second substrate comprising:
a third portion arranged adjacent to the first portion of the first substrate, wherein the first portion comprises a first cavity and the third portion comprises a second cavity that is conjoined with the first cavity to form a pressure equalizing chamber, wherein the MEMS membrane is interposed between the measurement chamber and the pressure equalizing chamber; and
a fourth portion laterally arranged with respect to the third portion, wherein the second portion comprises a third cavity and the fourth portion comprises a fourth cavity that is conjoined with the third cavity to form an enclosed hollow space.

20 . The gas sensor of claim 19 , wherein the emitter element is interposed between the measurement chamber and the enclosed hollow space.

21 . The gas sensor of claim 19 , wherein the pressure equalizing chamber is sealed from the measurement chamber by the MEMS membrane.

22 . The gas sensor of claim 19 , wherein the MEMS membrane includes an opening that connects the measurement chamber to the pressure equalizing chamber.

23 . The gas sensor of claim 18 , wherein the measurement gas converts the electromagnetic radiation into a photoacoustic signal, and the sensor element is configured to measure the photoacoustic signal by detecting deflections of the MEMS membrane.

24 . The gas sensor of claim 18 , further comprising:
a perforated counter electrode arranged between the MEMS membrane and at least a portion of the measurement chamber, wherein the perforated counter electrode is configured to reflect infrared radiation.

25 . The gas sensor of claim 24 , wherein the perforated counter electrode is capacitively coupled to the MEMS membrane.

Assignees

• Infineon Technologies Ag
• Fraunhofer Ges Forschung

Inventors

• Kolb Stefan
• Dehe Alfons
• Huber Jochen
• Jost Franz
• Theuss Horst
• Wiedmeier Wilhelm
• Woellenstein Juergen

Classifications

• G01N2021/1704

  in gases · CPC title

• G01N29/30

  Arrangements for calibrating or comparing, e.g. with standard objects · CPC title

• G01N29/2418

  using optoacoustic interaction with the material, e.g. laser radiation, photoacoustics (photoacoustic cells G01N21/1702; measuring characteristics of vibrations by using radiation-sensitive means G01H9/00; acousto-optical conversion techniques for short-range imaging G01S15/8965; sound-producing devices using laser bundle G10K15/046) · CPC title

• G01N29/022

  Fluid sensors based on microsensors, e.g. quartz crystal-microbalance [QCM], surface acoustic wave [SAW] devices, tuning forks, cantilevers, flexural plate wave [FPW] devices (microdevices per se B81B) · CPC title

• G01N21/1702 Primary

  with opto-acoustic detection, e.g. for gases or analysing solids · CPC title