Micromechanical flow sensor with tensile coating

• US 7,713,772 B2
• Filed: 10/03/2006
• Issued: 05/11/2010
• Est. Priority Date: 01/10/2001
• Status: Active Grant

• Current Assignee: Sensirion Holding AG
• Original Assignee: Sensirion AG (Sensirion Holding AG)
• Inventors: Cilento, Tommasso Francesco, Vanha, Ralph Steiner
• Primary Examiner(s): Sefer; A.
• Assistant Examiner(s): Parker; Allen L
• Application Number:
  US11/542,875
• Publication Number:
  US 20070231942A1
• Time in Patent Office: 1,316 Days
• Field of Search: 737/23, 737/25, 737/26, 735/143.4, 737/90, 438/53, 338/22.SD, 338/45
• US Class Current: 438/53
• CPC Class Codes: G01F 1/6845 Micromachined devices
• CPC Class Codes: G01F 15/10 Preventing damage by freezing or excess pressure or insufficient pressure

Abstract

A sensor integrated on a semiconductor device (1), in particular a flow sensor, comprises a measuring element (2) on a membrane (5). In order to prevent a buckling of the membrane (5) a tensile coating (9) is applied. The coating covers the membrane, but it preferably leaves all the active electronic components integrated on the semiconductor chip (1) uncovered, such that their electrical properties are not affected.

Claims

1. A method for producing a sensor having a semiconductor device on which a measuring element and a circuit with active electronic components are integrated, the measuring element being arranged on a membrane above an opening or recess of the semiconductor device, said method comprising the steps of

applying a compressive protective layer on the semiconductor device,

removing the compressive protective layer at least in a region of the membrane and

applying a tensile coating at least in the region of the membrane.

2. The method of claim 1 wherein, below the protective layer, a topmost metal layer is arranged and wherein, for removing the protective layer, the protective layer is etched off by a first etching agent, wherein the topmost metal layer acts as an etch stop, whereupon the topmost metal layer is removed by a second etching agent.

3. The method of claim 1 wherein the step of removing the compressive protective layer comprises etching.

4. The method of claim 3 wherein a metal layer below said compressive protective layer is used as an etch stop while etching off said compressive protective layer.

5. The method of claim 4 further comprising the step of etching off said metal layer after etching of said protective layer.

6. The method of claim 4 wherein said metal layer is structured to extend over the whole membrane.

7. The method of claim 3 further comprising the step of applying several metal layers below said protective layer.

8. The method of claim 1 further comprising the steps of

applying at least one scribe line to said semiconductor device, and

applying said tensile coating on a seal ring of said scribe line with a separating layer between said seal ring and said tensile coating.

9. The method of claim 8 wherein said separating layer is a silicon oxide layer.

10. The method of claim 1 further comprising the step of providing a separating layer between said tensile coating and any metal structures of said semiconductor device.

12. The method of claim 1 wherein, below the protective layer, a conducting layer extends over said opening or recess and wherein, for removing the protective layer, the protective layer is etched off by a first etching agent, wherein the conducting layer acts as an etch stop conducting layer, whereupon the etch stop conducting layer is removed by a second etching agent.

13. The method of claim 12 wherein at least one further conducting layer is arranged between said etch stop conducting layer and said protective layer, wherein said further conducting layer does not extend over said recess or opening.

14. The method of claim 12 wherein at least one further conducting layer is arranged below said etch stop conducting layer and is used for manufacturing conductive structures in said membrane.

11. A method for producing a sensor having a semiconductor device on which a measuring element and a circuit with active electronic components are integrated, the measuring element being arranged on a membrane above an opening or recess of the semiconductor device, said method comprising the steps of

applying at least one metal layer on the semiconductor device,

applying at least one compressive layer on the semiconductor device,

removing the compressive layer at least in a region of the membrane by etching said compressive layer off and using said metal layer as an etch stop and

applying a tensile coating at least in the region of the membrane.