METHOD TO PACKAGE MULTIPLE MEMS SENSORS AND ACTUATORS AT DIFFERENT GASES AND CAVITY PRESSURES

• US 20140227816A1
• Filed: 12/10/2013
• Published: 08/14/2014
• Est. Priority Date: 12/10/2012
• Status: Active Grant

• Current Assignee: Movella Incorporated (Movella Holdings, Inc.)
• Original Assignee: mCube, Inc.
• Inventors: Yoneoka, Shingo, ZHANG, WENHUA
• Granted Patent: US 9,174,838 B2
• Time in Patent Office: Days
• US Class Current: 438/48
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 2201/0242 Gyroscopes
• CPC Class Codes: B81B 2201/0292 Sensors not provided for in B81B2201/0207 - B81B2201/0285
• CPC Class Codes: B81B 7/0041 maintaining a controlled atmosphere with techniques not provided for in B81B7/0038
• 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 1/00293 maintaining a controlled atmosphere with processes not provided for in B81C1/00285
• CPC Class Codes: B81C 1/00333 Aspects relating to packaging of MEMS devices, not covered by groups B81C1/00269 - B81C1/00325
• CPC Class Codes: B81C 2203/0109 Bonding an individual cap on the substrate
• CPC Class Codes: B81C 2203/0145 Hermetically sealing an opening in the lid
• CPC Class Codes: B81C 2203/0154 Moulding a cap over the MEMS device
• CPC Class Codes: H01L 21/56 Encapsulations, e.g. encapsulation layers, coatings
• CPC Class Codes: H10N 30/302 Sensors

Abstract

A method for fabricating a multiple MEMS device. A semiconductor substrate having a first and second MEMS device, and an encapsulation wafer with a first cavity and a second cavity, which includes at least one channel, can be provided. The first MEMS can be encapsulated within the first cavity and the second MEMS device can be encapsulated within the second cavity. These devices can be encapsulated within a provided first encapsulation environment at a first air pressure, encapsulating the first MEMS device within the first cavity at the first air pressure. The second MEMS device within the second cavity can then be subjected to a provided second encapsulating environment at a second air pressure via the channel of the second cavity.

Claims

1. A method for fabricating a multiple MEMS device comprising:

providing a semiconductor substrate having a first MEMS device and a second MEMS device;

providing an encapsulation wafer comprising a first cavity and a second cavity, wherein the second cavity comprises at least one channel;

providing a first encapsulation environment at a first air pressure;

encapsulating the first MEMS device within the first cavity and the second MEMS device within the second cavity, while within the first encapsulation environment, to encapsulate the first MEMS device within the first cavity at the first air pressure;

providing a second encapsulating environment at a second air pressure, wherein the second air pressure is different from the first air pressure;

subjecting the second MEMS device within the second cavity to the second encapsulation environment via the at least one channel; and

sealing the at least one channel, while within the second encapsulation environment, to encapsulate the second MEMS device within the second cavity at the second air pressure.

2. The method of claim 1 wherein the first MEMS device is selected from a group consisting of:

a magnetometer, a gyroscope, an oscillator, a filter, an infrared sensor.

3. The method of claim 2 wherein the first air pressure is below atmospheric air pressure.

4. The method of claim 1 wherein the first MEMS device an accelerometer.

5. The method of claim 4 wherein the first air pressure is above atmospheric air pressure.

6. The method of claim 1 the first air pressure is below the second air pressure.

7. The method of claim 1 wherein the first encapsulation environment comprises a gas selected from a group consisting of:

helium, xenon, krypton, argon.

8. The method of claim 1 wherein sealing the at least one channel comprises depositing a layer of material using a process selected from a group consisting of:

CVD, PVD, sputtering, and evaporation.

9. The method of claim 1 further comprising:

providing an initial encapsulation wafer;

patterning a masking layer on top of the initial encapsulation wafer, wherein the masking layer comprises a first opening, a second opening, and a third opening, wherein a width of the third opening is substantially smaller than a width of the first opening or a width of the second opening;

etching the initial encapsulation wafer to form the encapsulation layer, wherein the first cavity is associated with the first opening, the second cavity is associated with the second opening, and the third opening is associated with the at least one channel.

10. The method of claim 9 wherein the depth of the at least one channel is less than a depth of the first cavity and less than a depth of the second cavity.

11. A method for fabricating a multiple MEMS device comprising:

providing a semiconductor substrate having a first MEMS device and a second MEMS device;

providing an initial encapsulation wafer;

patterning a masking layer on top of the initial encapsulation wafer, wherein the masking layer comprises a first opening, a second opening, and a third opening, wherein a width of the third opening is substantially smaller than a width of the first opening or a width of the second opening;

etching the initial encapsulation wafer to form an encapsulation layer, wherein a first cavity is associated with the first opening, a second cavity is associated with the second opening, and the third opening is associated with at least one channel providing a first encapsulation environment at a first air pressure;

encapsulating the first MEMS device within the first cavity and the second MEMS device within the second cavity, while within the first encapsulation environment, to encapsulate the first MEMS device within the first cavity at the first air pressure;

providing a second encapsulating environment at a second air pressure, wherein the second air pressure is different from the first air pressure;

subjecting the second MEMS device within the second cavity to the second encapsulation environment via the at least one channel; and

sealing the at least one channel, while within the second encapsulation environment, to encapsulate the second MEMS device within the second cavity at the second air pressure.

12. The method of claim 11 further comprising opening one or more bond pads.

13. The method of claim 11 wherein the first air pressure is below atmospheric air pressure and wherein the first MEMS device is selected from a group consisting of:

a magnetometer, a gyroscope, an oscillator, a filter, an infrared sensor.

14. The method of claim 11 wherein the first air pressure is above atmospheric air pressure and wherein the first MEMS device is an accelerometer.

15. The method of claim 11 wherein the depth of the one channel is less than a depth of the first cavity and less than a depth of the second cavity.

16. A method for fabricating a multiple MEMS device comprising:

providing a semiconductor substrate having a first MEMS device and a second MEMS device, the semiconductor substrate having a device layer, an interconnect layer or dielectric layer, and at least one channel;

providing an encapsulation wafer comprising a first cavity and a second cavity;

providing a first encapsulation environment at a first air pressure;

encapsulating the first MEMS device within the first cavity and the second MEMS device within the second cavity, while within the first encapsulation environment, to encapsulate the first MEMS device within the first cavity at the first air pressure, the encapsulation wafer being bonded to the device layer;

providing a second encapsulating environment at a second air pressure, wherein the second air pressure is different from the first air pressure;

subjecting the second MEMS device within the second cavity to the second encapsulation environment via the at least one channel; and

sealing the at least one channel, while within the second encapsulation environment, to encapsulate the second MEMS device within the second cavity at the second air pressure.

17. The method of claim 16 wherein the at least one channel is provided within the device layer.

18. The method of claim 16 wherein the at least one channel is provided within the interconnect layer or dielectric layer.

19. The method of claim 16 wherein the first air pressure is below atmospheric air pressure and wherein the first MEMS device is selected from a group consisting of:

a magnetometer, a gyroscope, an oscillator, a filter, an infrared sensor.

20. The method of claim 16 wherein the first air pressure is above atmospheric air pressure and wherein the first MEMS device is an accelerometer.