STRESS ISOLATED MEMS STRUCTURES AND METHODS OF MANUFACTURE

• US 20130276544A1
• Filed: 04/20/2012
• Published: 10/24/2013
• Est. Priority Date: 04/20/2012
• Status: Active Grant

• Current Assignee: Rosemount Aerospace, Inc. (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: Rosemount Aerospace, Inc. (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Potasek, David P., Christenson, John C., Satterlund, Bruce H., Phillips, Randy, Holmquist, Dave
• Granted Patent: US 9,010,190 B2
• Time in Patent Office: Days
• US Class Current: 73/715
• CPC Class Codes: B81B 7/0048 between the MEMS die and the substrate
• CPC Class Codes: H01L 2224/48147 with an intermediate bond, e.g. continuous wire daisy chain
• CPC Class Codes: H01L 2224/48472 the other connecting portion not on the bonding area also being a wedge bond, i.e. wedge-to-wedge

Abstract

A MEMS pressure sensor may be manufactured to include a backing substrate having a diaphragm backing portion and a pedestal portion. A diaphragm substrate may be manufactured to include a pedestal portion and a diaphragm that is mounted to the diaphragm backing portion of the backing substrate to form a stress isolated MEMS die. The pedestal portions of the backing and diaphragm substrates form a pedestal of the stress isolated MEMS die. The pedestal is configured for isolating the diaphragm from stresses including packaging and mounting stress imparted on the stress isolated MEMS die.

Claims

1. A microstructure device comprising:

a device body including;

a stress-isolated region including at least one stress-sensitive component; and

a mounting base configured and adapted to be affixed to a package housing the device body, wherein the mounting base is laterally offset from the stress isolated region along the device body for isolating the stress-sensitive component from packaging stress imparted on the mounting base.

2. A microstructure device as recited in claim 1, wherein the device body is a planar wafer component defining the stress-sensitive component and mounting base.

3. A microstructure device as recited in claim 2, wherein the stress-isolated region and the mounting base are separated by a pedestal defined in the device body, the pedestal having a width less than that of the stress-isolated region and of the mounting base.

4. A microstructure device as recited in claim 1, further comprising a package mounted to an edge of the mounting base, wherein the edge of the mounting base faces away from the stress-isolated region of the device body.

5. A microstructure device as recited in claim 1, wherein the stress-sensitive component includes a media sensor selected from the group consisting of a humidity sensor, flow sensor, chemical sensor, gas analyzer, particle detector, and pressure sensor, and wherein the media sensor is in fluid communication with ambient conditions through a flow passage defined between the device body and a second body that is a wafer component adhered to the device body.

6. A microstructure device as recited in claim 5, wherein the flow passage has a cross-section the smallest linear dimension of which is smaller than that of a sensor cavity in fluid communication therewith adjacent to the media sensor.

7. A microstructure device as recited in claim 1, wherein the stress-isolated region, stress-sensitive component, and mounting base are all defined in a single crystal silicon wafer component.

8. A MEMS pressure sensor comprising:

a backing substrate including a diaphragm backing portion and a pedestal portion; and

a diaphragm substrate including a pedestal portion and a diaphragm mounted to the diaphragm backing portion of the backing substrate to form a MEMS die, wherein the pedestal portions of the backing and diaphragm substrates form a pedestal of the MEMS die configured for isolating the diaphragm from packaging stress imparted on a mounting base of the MEMS die opposite the diaphragm across the pedestal.

9. A MEMS pressure sensor as recited in claim 8, further comprising a package configured and adapted to house the MEMS die, wherein the mounting base of the MEMS die is mounted to the package to isolate the diaphragm from the package for packaging stress mitigation.

10. A MEMS pressure sensor as recited in claim 8, wherein the pedestal portion of the backing substrate is substantially in plane with and narrower than the diaphragm backing portion, and wherein the pedestal portion of the diaphragm substrate is substantially in plane with and narrower than the diaphragm.

11. A MEMS pressure sensor as recited in claim 8, wherein the diaphragm is thinner than a diaphragm rim surrounding at least a portion of the diaphragm, wherein the diaphragm rim is adhered to the diaphragm backing portion of the backing substrate so that a void is defined between the diaphragm and the diaphragm backing portion of the backing substrate.

12. A MEMS pressure sensor as recited in claim 11, wherein a pressure port is defined through the backing substrate for fluid communication between the void and the environment external thereto.

13. A MEMS pressure sensor comprising:

a diaphragm substrate including a diaphragm substantially surrounded by a diaphragm rim; and

a backing substrate having a diaphragm backing portion mounted to the diaphragm rim to form a MEMS die with a diaphragm void defined between the diaphragm and the backing portion, wherein a channel is defined through the diaphragm and backing substrates, a portion of the channel substantially surrounding the diaphragm rim, wherein two ends of the channel define a pedestal therebetween in the diaphragm and backing substrates that is substantially in plane with the diaphragm such that the diaphragm and diaphragm backing portion are suspended from the pedestal for mitigation of packaging stress on the diaphragm imparted on a mounting base of the MEMS die opposite the diaphragm across the pedestal.

14. A MEMS pressure sensor as recited in claim 13, wherein the diaphragm and backing substrates include an outer rim outboard of the portion of the channel substantially surrounding the diaphragm rim, the outer rim being spaced apart from the diaphragm and diaphragm backing portion across the channel.

15. A MEMS pressure sensor as recited in claim 13, further comprising:

a topping wafer mounted to the diaphragm substrate on the outer rim and mounting base with a topping void defined between the topping wafer and the diaphragm; and

a base wafer mounted to the backing substrate on the outer rim and mounting base with a base void defined between the base wafer and the diaphragm backing portion of the backing substrate, wherein the topping wafer, base wafer, outer rim, and mounting base form a diaphragm enclosure around the diaphragm and diaphragm backing portion for mitigation of packaging stress on the diaphragm from the enclosure.

16. A MEMS pressure sensor as recited in claim 15, further comprising an integrated electronics component mounted to one of the topping wafer and base wafer.

17. A MEMS pressure sensor as recited in claim 15, wherein the diaphragm void forms a first pressure space configured to deflect the diaphragm in a first direction under pressure, wherein the topping and base voids are in fluid communication through the channel in the diaphragm and backing substrates to form a second pressure space configured to deflect the diaphragm in a second direction opposite the first direction under pressure.

18. A MEMS pressure sensor as recited in claim 17, wherein the diaphragm enclosure includes a first pressure port in fluid communication with the first pressure space, wherein the second pressure space is hermetically sealed for sensing absolute pressure of an external pressure source in fluid communication with the first pressure space.

19. A MEMS pressure sensor as recited in claim 17, wherein the diaphragm enclosure includes a first pressure port and a second pressure port in fluid communication with the first and second pressure spaces, respectively, wherein the first and second pressure spaces are sealed from one another within the diaphragm enclosure for sensing differential pressure between respective first and second external pressure sources across the diaphragm.

20. A MEMS pressure sensor as recited in claim 19, further comprising a sensor package enclosing the diaphragm enclosure, wherein each of the first and second pressure ports of the diaphragm enclosure is in fluid communication with a respective pressure opening through the sensor package for connection to a respective pressure source, and wherein a hermetically sealed space is defined between the sensor package and the diaphragm enclosure for protecting the diaphragm enclosure from ambient conditions.