3D STACKED PIEZORESISTIVE PRESSURE SENSOR

• US 20160320255A1
• Filed: 03/28/2016
• Published: 11/03/2016
• Est. Priority Date: 04/09/2015
• Status: Active Grant

• Current Assignee: Vitesco Technologies USA, LLC (Continental AG)
• Original Assignee: Continental Automotive Systems, Inc. (Continental AG)
• Inventors: Chiou, Jen-Huang Albert, Kosberg, Robert C., Chen, Shiuh-Hui Steven
• Granted Patent: US 9,846,095 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B81B 2201/0264 Pressure sensors
• CPC Class Codes: B81B 2207/092 Buried interconnects in the substrate or in the lid
• CPC Class Codes: B81B 7/00 Microstructural systems; Auxiliary parts of microstructural devices or systems
• CPC Class Codes: B81C 1/00238 Joining a substrate with an electronic processing unit and a substrate with a micromechanical structure
• CPC Class Codes: B81C 2203/0792 Forming interconnections between the electronic processing unit and the micromechanical structure
• CPC Class Codes: G01L 19/0076 using buried connections
• CPC Class Codes: G01L 19/0084 to the outside of the housing other details about the housing see G01L19/14
• CPC Class Codes: G01L 9/0042 Constructional details associated with semiconductive diaphragm sensors, e.g. etching, or constructional details of non-semiconductive diaphragms details about the integration or bonding of piezoresistor in or on the diaphragm G01L9/0052 and G01L9/0057 respectively
• CPC Class Codes: G01L 9/0052 of piezoresistive elements circuits therefor G01L9/06
• CPC Class Codes: G01L 9/0055 bonded on a diaphragm
• CPC Class Codes: G01L 9/06 of piezo-resistive devices
• CPC Class Codes: H01L 2224/48137 the bodies being arranged next to each other, e.g. on a common substrate
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors

Abstract

In a microelectromechanical system (MEMS) pressure sensor, thin and fragile bond wires that are used in the prior art to connect a MEMS pressure sensing element to an application specific integrated circuit (ASIC) for the input and output signals between these two chips are replaced by stacking the ASIC on the MEMS pressure sensing element and connecting each other using conductive vias formed in the ASIC. Gel used to protect the bond wires, ASIC and MEMS pressure sensing element can be eliminated if bond wires are no longer used. Stacking the ASIC on the MEMS pressure sensing element and connecting them using conductive vias enables a reduction in the size and cost of a housing in which the devices are placed and protected.

Claims

1. A pressure sensor device comprising:

a MEMS pressure sensing element having first and second sides with a flexible diaphragm and a Wheatstone bridge circuit on the first side;

a first integrated circuit comprising a substrate with first and second sides, electronic circuitry formed into a predetermined portion of the first side and a recess formed into the second side, the second side of the first integrated circuit being attached to the first side of the MEMS pressure sensing element, the recess of the first integrated circuit and the first side of the MEMS pressure sensing element defining a substantially evacuated cavity;

a first plurality of conductive vias formed into the first integrated circuit substrate such that the first plurality of vias extend through the substrate and electrically connect the Wheatstone bridge circuit of the MEMS pressure sensing element to the circuitry formed into the first side of the first integrated circuit.

2. The pressure sensor device of claim 1, wherein the MEMS pressure sensing element has a plurality of electrical contacts on its first side, the pressure sensor device further comprising:

a layer of silicon dioxide between the first side of the MEMS pressure sensing element and the second side of the first integrated circuit, the layer of silicon dioxide forming a silicon fusion bond between the MEMS pressure sensing element and the integrated circuit; and

an intermetallic bond formed between at least one of the conductive vias and an electrical contact on the first side of the MEMS pressure sensing element.

3. The pressure sensor device of claim 1, wherein the MEMS pressure sensing element has a plurality of electrical contacts on its first side, the pressure sensor device further comprising:

a layer of glass frit located between the first side of the MEMS pressure sensing element and the second side of the first integrated circuit, the layer of glass frit forming a bond between the MEMS pressure sensing element and the first integrated circuit; and

a solder bump between at least one of the conductive vias and an electrical contact on the first side of the MEMS pressure sensing element.

4. The pressure sensor device of claim 3, wherein the layer of glass frit is patterned to provide at least one media path through the layer of glass frit, the media path being configured to allow a predetermined fluid to pass through the media path and to the recess formed into the second side of the first integrated circuit.

5. The pressure sensor device of claim 1, wherein the plurality of conductive vias are symmetrically distributed in the first integrated circuit substrate.

6. The pressure sensor device of claim 1, further comprising a second integrated circuit attached to the first side of the first integrated circuit, the second integrated circuit comprising a substrate with first and second sides and electronic circuitry formed into a predetermined portion of its first side.

7. The pressure sensor device of claim 6, further comprising a second plurality of conductive vias formed into the second integrated circuit substrate such that the second plurality of vias extend through the substrate of the second integrated circuit and electrically connect circuitry of the first integrated circuit to circuitry of the second integrated circuit.

8. The pressure sensor device of claim 1, wherein the first integrated circuit substrate comprises a third vertical side, which is substantially orthogonal to the first and second sides, the second side further comprising at least one trench formed to extend into the recess and through the third vertical side.

9. The pressure sensor of device of claim 1, further comprising a pedestal attached to the second side of the MEMS pressure sensing element, the pedestal comprising an aperture, which is substantially aligned to the flexible diaphragm.

10. A pressure sensor module comprising:

a pressure sensor device comprising;

a MEMS pressure sensing element having first and second sides with a flexible diaphragm and a Wheatstone bridge circuit on the first side;

a first integrated circuit comprising a substrate with first and second sides, electronic circuitry formed into a predetermined portion of the first side and a recess formed into the second side, the second side of the first integrated circuit being attached to the first side of the MEMS pressure sensing element, the recess of the first integrated circuit and the first side of the MEMS pressure sensing element defining a substantially evacuated cavity; and

a first plurality of conductive vias formed into the first integrated circuit substrate such that the first plurality of vias extend through the substrate and electrically connect the Wheatstone bridge circuit of the MEMS pressure sensing element to the circuitry formed into the first side of the first integrated circuit;

a housing having a pocket that encloses the pressure sensor device and a pressure port configured to allow a predetermined fluid to apply pressure to the diaphragm; and

a lead frame that extends from an electrical contact on the first side of the first integrated circuit through the housing, the electrical contact on the first side of the first integrated circuit comprising at least one of a solder bump and an electrically conductive adhesive.

11. The pressure sensor module of claim 10, further comprising a layer of adhesive between the first integrated circuit and an interior surface of the pocket, the layer of adhesive being configured to mount the pressure sensor device to an interior surface of the pocket and substantially cover the electrical contact on the first side of the first integrated circuit.

12. The pressure sensor module of claim 10, wherein the MEMS pressure sensing element has a plurality of electrical contacts on its first side, the pressure sensor device further comprising:

a layer of silicon dioxide between the first side of the MEMS pressure sensing element and the second side of the first integrated circuit, the layer of silicon dioxide forming a silicon fusion bond between the MEMS pressure sensing element and the first integrated circuit; and

an intermetallic bond formed between at least one of the conductive vias and an electrical contact on the first side of the MEMS pressure sensing element.

13. The pressure sensor module of claim 10, wherein the MEMS pressure sensing element has a plurality of electrical contacts on its first side, the pressure sensor device further comprising:

a layer of glass frit located between the first side of the MEMS pressure sensing element and the second side of the first integrated circuit, the layer of glass frit forming a bond between the MEMS pressure sensing element and the first integrated circuit; and

a solder bump between at least one of the conductive vias and an electrical contact on the first side of the MEMS pressure sensing element.

14. The pressure sensor module of claim 10, wherein the layer of glass frit is patterned to provide at least one media path through the layer of glass frit, the media path being configured to allow a predetermined fluid to pass through to the recess formed into the second side of the first integrated circuit.

15. The pressure sensor module of claim 10, wherein the plurality of conductive vias are symmetrically distributed in the first integrated circuit substrate.

16. The pressure sensor module of claim 10, further comprising a second integrated circuit attached to the first side of the first integrated circuit, the second integrated circuit comprising a substrate with first and second sides and electronic circuitry formed into a predetermined portion of its first side.

17. The pressure sensor module of claim 16, further comprising a second plurality of conductive vias formed into the second integrated circuit substrate such that the second plurality of vias extend through the substrate of the second integrated circuit and electrically connect circuitry of the first integrated circuit to circuitry of the second integrated circuit.

18. The pressure sensor module of claim 10, wherein the first integrated circuit substrate comprises a third vertical side, which is substantially orthogonal to the first and second sides, the second side further comprising at least one trench formed to extend into the recess and through the third vertical side.

19. The pressure sensor module of claim 10, further comprising a pedestal attached to the second side of the MEMS pressure sensing element, the pedestal comprising an aperture, which is substantially aligned to the flexible diaphragm.

20. A pressure sensor module comprising:

a pressure sensor device comprising;

a MEMS pressure sensing element having first and second sides with a flexible diaphragm and a Wheatstone bridge circuit on the first side;

a first integrated circuit comprising a substrate with first and second sides, electronic circuitry formed into a predetermined portion of the first side and a recess formed into the second side, the second side of the first integrated circuit being attached to the first side of the MEMS pressure sensing element, the recess of the first integrated circuit and the first side of the MEMS pressure sensing element defining a substantially evacuated cavity; and

a first plurality of conductive vias formed into the first integrated circuit substrate such that the first plurality of vias extend through the substrate and electrically connect the Wheatstone bridge circuit of the MEMS pressure sensing element to the circuitry formed into the first side of the first integrated circuit;

a housing having a pocket that encloses the pressure sensing device and a pressure port configured to allow a predetermined fluid to apply pressure to the diaphragm;

a lead frame that extends from inside the pocket through the housing;

a bond wire that extends from an electrical contact on the first side of the first integrated circuit to the lead frame;

an adhesive layer located between the second side of the MEMS pressure sensing element and an interior surface of the pocket through which the pressure port is formed, the adhesive layer surrounding and sealing the pressure port to the second side of the MEMS pressure sensing element.

21. The pressure sensor module of claim 20, further comprising a layer of gel inside the pocket and substantially covering the pressure sensor device.

22. The pressure sensor module of claim 20, further comprising a conformal coating over the pressure sensor device, the bond wire and at least part of the lead frame.

23. The pressure sensor module of claim 22, further comprising a layer of glass frit between the MEMS pressure sensing element and the first integrated circuit, wherein the layer of glass frit is patterned to provide at least one media path through the layer of glass frit, the media path being configured to allow a predetermined fluid to pass through to the media path to the recess formed into the second side of the first integrated circuit.

24. The pressure sensor module of claim 20, wherein the MEMS pressure sensing element has a plurality of electrical contacts on its first side, the pressure sensor device further comprising:

a layer of silicon dioxide between the first side of the MEMS pressure sensing element and the second side of the integrated circuit, the layer of silicon dioxide forming a silicon fusion bond between the MEMS pressure sensing element and the first integrated circuit; and

an intermetallic bond formed between at least one of the conductive vias and an electrical contact on the first side of the MEMS pressure sensing element.

25. The pressure sensor module of claim 20, wherein the MEMS pressure sensing element has a plurality of electrical contacts on its first side, the pressure sensor device further comprising:

a layer of glass frit located between the first side of the MEMS pressure sensing element and the second side of the first integrated circuit, the layer of glass frit forming a bond between the MEMS pressure sensing element and the first integrated circuit; and

a solder bump between at least one of the conductive vias and an electrical contact on the first side of the MEMS pressure sensing element.

26. The pressure sensor module of claim 20, wherein the plurality of conductive vias are symmetrically distributed in the first integrated circuit substrate.

27. The pressure sensor module of claim 20, further comprising a second integrated circuit attached to the first side of the first integrated circuit, the second integrated circuit comprising a substrate with first and second sides and electronic circuitry formed into a predetermined portion of its first side.

28. The pressure sensor module of claim 27, further comprising a second plurality of conductive vias formed into the second integrated circuit substrate such that the second plurality of vias extend through the substrate of the second integrated circuit and electrically connect circuitry of the first integrated circuit to circuitry of the second integrated circuit.

29. The pressure sensor module of claim 20, wherein the first integrated circuit substrate comprises a third vertical side, which is substantially orthogonal to the first and second sides, the second side further comprising at least one trench formed to extend into the recess and through the third vertical side.

30. The pressure sensor module of claim 20, further comprising a pedestal attached to the second side of the MEMS pressure sensing element, the pedestal comprising an aperture, which is substantially aligned to the flexible diaphragm.