Membrane-based sensor device with non-dielectric etch-stop layer around substrate recess

• US 9,224,658 B2
• Filed: 01/22/2014
• Issued: 12/29/2015
• Est. Priority Date: 01/31/2013
• Status: Active Grant

• Current Assignee: Sensirion AG (Sensirion Holding AG)
• Original Assignee: Sensirion AG (Sensirion Holding AG)
• Inventors: Hummel, Rene, Sunier, Robert, Kuemin, Cyrill
• Primary Examiner(s): Armand, Marc
• Assistant Examiner(s): Boulghassoul, Younes
• Application Number:
  US14/161,267
• Publication Number:
  US 20140210036A1
• Time in Patent Office: 706 Days
• Field of Search: 257/467, 438/49
• US Class Current: 1/1
• CPC Class Codes: G01F 1/6845 Micromachined devices
• CPC Class Codes: G01N 27/04 by investigating resistance
• CPC Class Codes: G01N 27/128 Microapparatus
• CPC Class Codes: G01N 27/14 of an electrically-heated body in dependence upon change of temperature
• CPC Class Codes: H01L 21/84 the substrate being other than a semiconductor body, e.g. being an insulating body

Abstract

A sensing device has a semiconductor substrate with an opening and a membrane spanning the opening. A heater is arranged on the membrane. To reduce the thermal conductivity of the membrane, a recess is etched into the membrane from below.

Claims

1. A sensor device comprising

a substrate having a top and a bottom surface and an opening extending between said top and bottom surfaces,

a batch of material layers applied to said top surface, wherein at least some of said material layers extend over said opening for forming a membrane,

a heater arranged on said membrane,

wherein said sensor device comprises a recess extending from below into said batch of material layers at a location of said membrane,

wherein said batch of material layers further comprises at least one non-dielectric etch-stop layer extending in a ring around said recess, and

wherein said ring is at level with a to surface of the recess.

2. The sensor device of claim 1 wherein said recess has a depth of at least 1 μ

m.

3. The sensor device of claim 2, wherein said recess has a depth of at least 3 μ

m.

4. The sensor device of claim 1 wherein said recess has a cross section area of at least 80% of a cross section area of an upper end of said opening.

5. The sensor device of claim 4, wherein said recess has a cross section equal to the cross section of the upper end of said opening.

6. The sensor device of claim 1 wherein said batch of material layers comprises a plurality of structured dielectric layers and a plurality of structured metal layers.

7. The sensor device of claim 1, wherein said ring has a width between 1 and 20 μ

m.

8. The sensor device of claim 7, wherein said non-dielectric etch-stop layer is of aluminum or copper.

9. The sensor device of claim 1 wherein said membrane comprises at least one SiN-layer under tensile stress.

10. The sensor device of claim 1 further comprising

at least one patch of a sensing material arranged on said membrane, and

electrodes contacting said sensing material.

11. The sensor device of claim 10, wherein said at least one patch of a sensing material is a metal oxide.

12. The sensor device of claim 10, wherein said electrodes are metal electrodes.

13. The sensor device of claim 1 wherein said heater comprises at least one metal conductor.

14. The sensor device of claim 13, wherein said at least one metal conductor is a tungsten conductor.

15. The sensor device of claim 1 further comprising processing circuitry integrated on said substrate.

16. The sensor device of claim 15 wherein said processing circuitry comprises at least one amplifier, analog/digital-converter or interface circuitry.

17. The sensor device of claim 1 further comprising a silicon plate arranged at a bottom of said membrane, with a gap formed around said plate between said plate and said substrate.

18. The sensor device of claim 17, wherein said substrate is an SOI structure having a silicon handle layer, an insulating layer and a silicon layer, with said insulating layer arranged between said silicon handle layer and said silicon layer.

19. The sensor device of claim 1, wherein said sensor device is a gas sensor or a humidity sensor.

20. The sensor device of claim 1 wherein said sensor device is a flow sensor comprising at least one temperature sensor arranged on said membrane.