3D stacked piezoresistive pressure sensor

Patent metadata

Field	Value
Publication number	US-9846095-B2
Application number	US-201615082336-A
Country	US
Kind code	B2
Filing date	Mar 28, 2016
Priority date	Apr 9, 2015
Publication date	Dec 19, 2017
Grant date	Dec 19, 2017

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.

First claim

What is claimed is:

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; and
at least one of:
i) 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;
and
ii) 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 an electrically conductive protuberance between at least one of the conductive vias and an electrical contact on the first side of the MEMS pressure sensing element.

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

3. 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.

4. The pressure sensor device of claim 3 , 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.

5. 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.

6. 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 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; and
at least one of:
i) 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, the second side further comprising at least one trench formed to extend into the recess; 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;
and
ii) 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 an electrically conductive protuberance between at least one of the conductive vias and an electrical contact on the first side of the MEMS pressure sensing element, wherein the layer of glass frit is patterned to provide at least one media path through the layer of glass fit, 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.

7. The pressure sensor device of claim 6 , wherein the plurality of conductive vias are symmetrically distributed in the first integrated circuit substrate.

8. The pressure sensor device of claim 6 , 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.

9. The pressure sensor device of claim 8 , 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.

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 an electrically conductive protuberance 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 substan

Assignees

• Continental automotive systems inc

Inventors

• Chiou Jen-Huang Albert
• Kosberg Robert C
• Chen Shiuh-Hui Steven

Classifications

• H10W72/884

  Die-attach connectors and bond wires · CPC title

• H10W90/753

  between laterally-adjacent chips · CPC title

• G01L19/0076

  using buried connections · CPC title

• G01L19/148

  Details about the circuit board integration, e.g. integrated with the diaphragm surface or encapsulation · CPC title

• B81B7/0025

  Protection against chemical alteration · CPC title