SYSTEMS AND METHODS FOR A THREE-LAYER CHIP-SCALE MEMS DEVICE

• US 20120126349A1
• Filed: 11/15/2011
• Published: 05/24/2012
• Est. Priority Date: 11/23/2010
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Horning, Robert D., Supino, Ryan
• Granted Patent: US 9,171,964 B2
• Time in Patent Office: Days
• US Class Current: 257/417
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 2201/0242 Gyroscopes
• CPC Class Codes: B81B 2201/025 Inertial sensors not provided for in B81B2201/0235 - B81B2201/0242
• CPC Class Codes: B81B 7/0032 Packages or encapsulation processes for packaging MEMS B81C1/00261; packaging of smart-MEMS B81C1/0023
• CPC Class Codes: B81B 7/0038 using materials for controlling the level of pressure, contaminants or moisture inside of the package, e.g. getters
• CPC Class Codes: B81B 7/0074 3D packaging, i.e. encapsulation containing one or several MEMS devices arranged in planes non-parallel to the mounting board
• CPC Class Codes: B81B 7/0077 Other packages not provided for in groups B81B7/0035 - B81B7/0074
• CPC Class Codes: B81C 2201/019 Bonding or gluing multiple substrate layers
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 29/84 controllable by variation of applied mechanical force, e.g. of pressure
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details

Abstract

Systems and methods for a micro-electromechanical system (MEMS) device are provided. In one embodiment, a system comprises a first outer layer and a first device layer comprising a first set of MEMS devices, wherein the first device layer is bonded to the first outer layer. The system also comprises a second outer layer and a second device layer comprising a second set of MEMS devices, wherein the second device layer is bonded to the second outer layer. Further, the system comprises a central layer having a first side and a second side opposite that of the first side, wherein the first side is bonded to the first device layer and the second side is bonded to the second device layer.

Claims

1. A micro-electromechanical system (MEMS) device, the device comprising:

a first outer layer;

a first device layer comprising a first set of MEMS devices, wherein the first device layer is bonded to the first outer layer;

a second outer layer;

a second device layer comprising a second set of MEMS devices, wherein the second device layer is bonded to the second outer layer; and

a central layer having a first side and a second side opposite that of the first side, wherein the first side is bonded to the first device layer and the second side is bonded to the second device layer.

2. The MEMS device of claim 1, wherein the MEMS device is an inertial sensor assembly (ISA).

3. The MEMS device of claim 1, wherein:

the first set of MEMS devices comprises a first set of accelerometers and a first set of gyroscopes; and

the second set of MEMS devices comprises a second set of accelerometers and a second set of gyroscopes.

4. The MEMS device of claim 3, wherein the first set of gyroscopes and the second set of gyroscopes are hermetically sealed in a first atmosphere type and the first set of accelerometers and the second set of accelerometers are hermetically sealed in a second atmosphere type.

5. The MEMS device of claim 4, wherein the first atmosphere type is a vacuum environment.

6. The MEMS device of claim 3, wherein the second atmosphere type is a gaseous environment.

7. The MEMS device of claim 6, further comprising a channel extending from an external surface of the MEMS device to one of the first set of gyroscopes, the second set of gyroscopes, the first set of accelerometers, and the second set of accelerometers.

8. The MEMS device of claim 7, further comprising a sealing layer attached to an external side of the MEMS device, the sealing layer hermetically sealing the channel.

9. The MEMS device of claim 8, wherein the sealing layer includes a getter to preserve a vacuum environment that encloses the first set of gyroscopes.

10. The MEMS device of claim 8, wherein electrical connections extend around the sealing layer such that the MEMS device is mountable in a plurality of different positions.

11. A method for forming a MEMS device, the method comprising:

bonding a first device layer to a first outer layer, the first device layer comprising a first set of MEMS devices;

bonding a second device layer to a second outer layer, the second device layer comprising a second set of MEMS devices; and

bonding a central layer to the first device layer and the second device layer.

12. The method of claim 11, wherein bonding a central layer includes subsequently bonding the central layer to both the first device layer and the second device layer.

13. The method of claim 11, further comprising sealing a first MEMS device in the first set of MEMS devices and the second set of MEMS devices in a first atmosphere type and a second MEMS device in the first set of MEMS devices and the second set of MEMS devices in a second atmosphere type.

14. The method of claim 13, further comprising:

forming a channel in the first outer layer, the channel exposing the first MEMS device to the first atmosphere type; and

sealing the channel while the first MEMS device is exposed to the first atmosphere type.

15. The method of claim 13, wherein sealing the first MEMS in the first atmosphere type and the second MEMS device in the second atmosphere type comprises:

forming a conduit in the first outer layer, the conduit extending to a desired location on the first device layer;

filling the conduit with a conductive material such that the conductive material is in contact with the first device layer and the desired location is shorted to an outer surface of the first outer layer;

when the first device layer is bonded to the first outer layer and the central layer and the first device layer are anodically bonded to the first outer layer and the central layer in the first atmosphere type, removing a portion of the conductive material such that the desired location is not shorted to the outer surface of the first outer layer; and

performing a second anodic bond in the second atmosphere type.

16. The method of claim 13, wherein the first MEMS device is an accelerometer and the first atmosphere type is a gaseous environment and the second MEMS device is a gyroscope and the second atmosphere type is a vacuum.

17. The method of claim 16, wherein sealing the first MEMS device in the gaseous environment and the second MEMS device in the vacuum comprises:

forming outgassing material proximate to the first MEMS device, wherein the outgassing material disassociates into a gas when heated above a threshold temperature, wherein the first device layer and the second device layer are bonded to the first outer layer, the second outer layer, and the central layer in a vacuum below the threshold temperature;

when the first MEMS device is hermetically isolated from the second MEMS device, raising the temperature of the outgassing material above the threshold temperature.

18. The method of claim 16, further comprising:

forming a channel in the first outer layer, the channel exposing the second MEMS device to the vacuum; and

bonding a sealing layer to the first outer layer, the sealing layer sealing the channel, wherein the sealing layer comprises a getter that is in a continuous air cavity with the second MEMS device.

19. The method of claim 11, further comprising:

forming a plurality of MEMS devices in a plurality of joined wafers; and

singulating the plurality of MEMS devices into individual MEMS devices.

20. A micro-electromechanical system inertial measurement unit comprising:

a first outer glass layer;

a first device layer comprising a first set of accelerometers and a first set of gyroscopes, the first device layer bonded to the first outer glass wafer;

a second outer glass layer;

a second device layer comprising a second set of accelerometers and a second set of gyroscopes, the second device layer bonded to the second outer glass wafer; and

a central glass layer bonded to the first device layer and the second device layer,

wherein the first set of accelerometers and the second set of accelerometers are hermetically sealed in a first atmosphere and the first set of gyroscopes and the second set of gyroscopes are hermetically sealed in a second atmosphere,

wherein the first set of accelerometers and second set of accelerometers sense acceleration along three orthogonal axes and the first set of gyroscopes and the second set of gyroscopes sense rotation about three orthogonal axes.