Water proofing and water detection schemes for MEMS-based environmental sensing devices

• US 10,640,367 B2
• Filed: 09/28/2018
• Issued: 05/05/2020
• Est. Priority Date: 09/29/2017
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Vummidi Murali, Krishna Prasad, Lei, Kuolung, Yeh, Richard, Ma, Yun X.
• Primary Examiner(s): Mandala, Victor A
• Application Number:
  US16/147,537
• Publication Number:
  US 20190100428A1
• Time in Patent Office: 585 Days
• CPC Class Codes: B81B 2201/0214 Biosensors; Chemical sensors
• CPC Class Codes: B81B 2201/0264 Pressure sensors
• CPC Class Codes: B81B 2201/0278 Temperature sensors
• CPC Class Codes: B81B 2203/0127 Diaphragms, i.e. structures separating two media that can control the passage from one medium to another; Membranes, i.e. diaphragms with filtering function
• CPC Class Codes: B81B 2203/04 Electrodes
• CPC Class Codes: B81B 2207/012 the micromechanical device and the control or processing electronics being separate parts in the same package
• CPC Class Codes: B81B 2207/096 through the substrate
• CPC Class Codes: B81B 7/0029 Protection against environmental influences not provided for in groups B81B7/0012 - B81B7/0025
• CPC Class Codes: B81B 7/0058 for protecting against damages due to external chemical or mechanical influences, e.g. shocks or vibrations
• CPC Class Codes: B81B 7/0077 Other packages not provided for in groups B81B7/0035 - B81B7/0074
• CPC Class Codes: B81C 1/0023 Packaging together an electronic processing unit die and a micromechanical structure die MEMS packages B81B7/0032; MEMS packaging processes B81C1/00261
• CPC Class Codes: B81C 2203/0136 Growing or depositing of a covering layer
• CPC Class Codes: B81C 2203/0792 Forming interconnections between the electronic processing unit and the micromechanical structure

Abstract

A waterproofed environmental sensing device with water detection provisions includes an environmental sensor to sense one or more environmental properties. The device further includes an electronic integrated circuit implemented on a substrate and coupled to the environmental sensor via a wire bonding. An air-permeable cap structure is formed over the environmental sensor, and a protective layer is formed over the wire bonding to protect the wire bonding against damage.

Claims

1. A device comprising:

an environmental sensor configured to sense one or more environmental properties;

an electronic integrated circuit implemented on a substrate and coupled to the environmental sensor via a wire bonding;

an air-permeable cap structure formed over the environmental sensor;

a protective layer formed over the wire bonding to protect the wire bonding against a potential damage; and

interdigitated electrodes implementing capacitors capable of detecting environmental aggressors including water, wherein the interdigitated electrodes are realized using a top metal layer and passivation.

2. The device of claim 1, wherein the environmental sensor comprises a miniature environmental sensor, and wherein the miniature environmental sensor is configured to sense a gas or an environmental parameter including a pressure, a temperature or a humidity.

3. The device of claim 1, wherein the air-permeable cap structure is configured to protect a surface of the environmental sensor from environmental aggressors including water and oil.

4. The device of claim 3, wherein the air-permeable cap structure is made of a suitable material including silicon, and wherein the air-permeable cap structure includes a coated hydrophobic layer.

5. The device of claim 1, wherein the environmental sensor is formed in on electro-mechanical system (MEMS) structure and wire bonded to the electronic integrated circuit through an interposer including through-silicon vias (TSVs).

6. The device of claim 5, wherein the MEMS structure and the interposer are coupled to the electronic integrated circuit via flip-chip bonding;

and wherein the electronic integrated circuit includes one or more capacitive elements configured to detect presence of at least water and oil.

7. The device of claim 5, further comprising resistive routings configured to provide heat calibration (temperature coefficient offset) TCO and for ejecting water from a surface of the air permeable cap structure, wherein the resistive routings are implemented in the MEMS structure.

8. The device of claim 5, wherein strain isolation provisions are implemented in at least one of the electronic integrated circuit or the MEMS-structure.

9. A device comprising:

an environmental sensor configured to sense one or more environmental properties;

an electronic integrated circuit implemented on a substrate and coupled to the environmental sensor via a wire bonding;

an air-permeable cap structure formed over the environmental sensor; and

a protective layer formed over the wire bonding to protect die wire bonding against a potential damage, wherein the environmental sensor is formed in an electro-mechanical system (MEMS) structure and wire bonded to the electronic integrated circuit through an interposer including through-silicon visa (TSVs).

10. The device of claim 9, wherein the environmental sensor comprises a miniature environmental sensor, and wherein the miniature environmental sensor is configured to sense a gas or an environmental parameter including a pressure, a temperature or a humidity.

11. The device of claim 9, wherein the air-permeable cap structure is configured to protect a surface of the environmental sensor from environmental aggressors including water and oil.

12. The device of claim 11, wherein the air-permeable cap structure is made of a suitable material including silicon, and wherein the air-permeable cap structure includes a coated hydrophobic layer.

13. The device of claim 9, wherein the MEMS structure and the interposer are coupled to the electronic integrated circuit via flip-chip bonding, and wherein the electronic integrated circuit includes one or more capacitive elements configured to detect presence of at least water and oil.

14. The device of claim 9, further comprising resistive routings configured to provide heat for calibrating (temperature coefficient offset) TCO and for ejecting water from a surface of the air-permeable cap structure, wherein the resistive routings are implemented in the MEMS structure.

15. The device of claim 9, wherein strain isolation provisions are implemented in at least one of the electronic integrated circuit or the MEMS structure.