Micromechanical pressure sensor device and corresponding manufacturing method

• US 20150198493A1
• Filed: 01/08/2015
• Published: 07/16/2015
• Est. Priority Date: 01/14/2014
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: KAELBERER, Arnd, Reinmuth, Jochen, Classen, Johannes
• Granted Patent: US 9,709,451 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B81B 2201/025 Inertial sensors not provided for in B81B2201/0235 - B81B2201/0242
• CPC Class Codes: B81B 2201/0264 Pressure sensors
• CPC Class Codes: B81B 3/0037 For increasing stroke, i.e. achieve large displacement of actuated parts
• 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: B81C 1/00158 Diaphragms, membranes manufacture process for semi-permeable inorganic membranes B01D67/0039
• CPC Class Codes: B81C 1/00246 Monolithic integration, i.e. micromechanical structure and electronic processing unit are integrated on the same substrate
• CPC Class Codes: G01L 9/0072 using variations in capacitance
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/125 by capacitive pick-up

Abstract

A micromechanical pressure sensor device includes: an MEMS wafer having a front side and a rear side; a first micromechanical functional layer formed above the front side of the MEMS wafer; and a second micromechanical functional layer formed above the first micromechanical functional layer. A deflectable first pressure detection electrode is formed in one of the first and second micromechanical functional layers. A fixed second pressure detection electrode is formed spaced apart from and opposite the deflectable first pressure detection electrode. An elastically deflectable diaphragm area is formed above the front side of the MEMS wafer. An external pressure is applied to the diaphragm area via an access opening in the MEMS wafer, and the wafer is connected to the deflectable first pressure detection electrode via a plug-like joining area.

Claims

1. A micromechanical pressure sensor device, comprising:

an MEMS wafer having a front side and a rear side;

a first micromechanical functional layer formed above the front side of the MEMS wafer;

a second micromechanical functional layer formed above the first micromechanical functional layer;

a deflectable first pressure detection electrode formed in one of the first and second micromechanical functional layers;

a fixed second pressure detection electrode formed spaced apart from and opposite the deflectable first pressure detection electrode; and

an elastically deflectable diaphragm area formed above the front side of the MEMS wafer, wherein an external pressure is applied to the diaphragm area via an access opening in the MEMS wafer, and wherein the wafer is joined to the deflectable first pressure detection electrode via a plug-like joining area.

2. The micromechanical pressure sensor device as recited in claim 1, wherein the plug-like joining area is formed centrally on the diaphragm area so that the first pressure detection electrode is deflectable essentially untilted.

3. The micromechanical pressure sensor device as recited in claim 2, wherein the diaphragm area is formed in a third micromechanical functional layer, which is formed beneath the first micromechanical functional layer above the front side of the MEMS wafer.

4. The micromechanical pressure sensor device as recited in claim 2, wherein the deflectable first pressure detection electrode is formed in the first micromechanical functional layer, and the fixed second pressure detection electrode is formed in the second micromechanical functional layer.

5. The micromechanical pressure sensor device as recited in claim 2, wherein the deflectable first pressure detection electrode is formed in the second micromechanical functional layer, and the fixed second pressure detection electrode is formed in the first micromechanical functional layer.

6. The micromechanical pressure sensor device as recited in claim 2, wherein the deflectable first pressure detection electrode is formed in the second micromechanical functional layer, and the fixed second pressure detection electrode is formed in a capping device which is bonded to the MEMS wafer.

7. The micromechanical pressure sensor device as recited in claim 1, wherein the plug-like joining area is formed decentrally on the diaphragm area, so that the first pressure detection electrode is deflectable in a tilted manner, and two fixed second pressure detection electrodes which are electrically insulated from each other are formed spaced apart from and opposite the deflectable first pressure detection electrode, and wherein the first pressure detection electrode is differently deflectable with respect to the two fixed second pressure detection electrodes.

8. The micromechanical pressure sensor device as recited in claim 1, wherein the deflectable first pressure detection electrode is formed in the first micromechanical functional layer, the fixed second pressure detection electrode is formed in the second micromechanical functional layer, and a further fixed second pressure detection electrode is formed in a third micromechanical functional layer, which is formed beneath the first micromechanical functional layer above the front side of the MEMS wafer.

9. The micromechanical pressure sensor device as recited in claim 8, wherein the deflectable first pressure detection electrode is electrically connected via a spring device which is formed in the first micromechanical functional layer.

10. The micromechanical pressure sensor device as recited in claim 9, wherein a capping device is provided, which is bonded to the second micromechanical functional layer for enclosing a cavern at a predetermined enclosed pressure.

11. The micromechanical pressure sensor device as recited in claim 10, wherein the capping device is an evaluation wafer.

12. The micromechanical pressure sensor device as recited in claim 8, wherein the access opening is a through-hole in the MEMS wafer, through which the pressure is applied to the diaphragm area from the rear side.

13. The micromechanical pressure sensor device as recited in claim 8, wherein the access opening is a lateral access opening on the front side of the MEMS wafer.

14. A method for manufacturing a micromechanical pressure sensor device, comprising:

providing an MEMS wafer having a front side and a rear side;

forming a first micromechanical functional layer above the front side of the MEMS wafer;

forming a second micromechanical functional layer above the first micromechanical functional layer;

forming a deflectable first pressure detection electrode in one of the first and second micromechanical functional layers;

forming a fixed second pressure detection electrode spaced apart from and opposite the deflectable first pressure detection electrode;

forming an elastically deflectable diaphragm area above the front side of the MEMS wafer, to which external pressure is applied via an access opening in the MEMS wafer; and

joining the elastically deflectable diaphragm area to the deflectable first pressure detection electrode via a plug-like joining area.