MEMS DEVICE CALIBRATION

• US 20150362395A1
• Filed: 06/11/2014
• Published: 12/17/2015
• Est. Priority Date: 06/11/2014
• Status: Active Grant

• Current Assignee: ScioSense B.V. (Ams-Osram AG)
• Original Assignee: ams AG (Ams-Osram AG)
• Inventors: Goossens, Martijn, Besling, Willem Frederik Adrianus, Steeneken, Peter Gerard, van der Avoort, Casper, Pijnenburg, Remco Henricus Wilhelmus
• Granted Patent: US 9,513,184 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B81B 2201/02 Sensors
• CPC Class Codes: B81B 2201/0264 Pressure sensors
• CPC Class Codes: B81B 2207/11 Structural features, others than packages, for protecting a device against environmental influences
• CPC Class Codes: B81C 99/0035 Testing
• CPC Class Codes: G01L 19/04 Means for compensating for effects of changes of temperature , i.e. other than electric compensation
• CPC Class Codes: G01L 27/002 Calibrating, i.e. establishing true relation between transducer output value and value to be measured, zeroing, linearising or span error determination
• CPC Class Codes: G01L 27/005 Apparatus for calibrating pressure sensors

Abstract

One example discloses a MEMS device, including: a cavity having an internal environment; a seal isolating the internal environment from an external environment outside the MEMS device; wherein the seal is susceptible to damage in response to a calibration unsealing energy; wherein upon damage to the seal, a pathway forms which couples the internal environment to the external environment; and a calibration circuit capable of measuring the internal environment before and after damage to the seal.

Claims

1. A MEMS device, comprising:

a cavity having an internal environment;

a seal isolating the internal environment from an external environment outside the MEMS device;

wherein the seal is susceptible to damage in response to a calibration unsealing energy;

wherein upon damage to the seal, a pathway forms which couples the internal environment to the external environment; and

a calibration circuit capable of measuring the internal environment before and after damage to the seal.

2. The device of claim 1:

further comprising a hermetically sealed second device; and

wherein the calibration circuit is capable of generating a calibration value for the second device in response to measuring the internal environment before and after damage to the seal.

3. The device of claim 2:

wherein the second device is a pressure sensor.

4. The device of claim 1:

wherein the MEMS device is embedded in a package; and

wherein the seal is susceptible to damage in response to the calibration unsealing energy while within the package.

5. The device of claim 1:

wherein the unsealing energy is at least one from a group consisting of;

a heat source and a puncturing device.

6. The device of claim 5:

wherein the heat source is at least one from a group consisting of;

an electrical current and a laser.

7. The device of claim 1:

wherein the seal is a fusible link; and

wherein the fusible link can damage the seal in response to an electrical current.

8. The device of claim 1:

wherein the damage the seal is susceptible to includes at least one from a group consisting of;

rupturing, breaching, breaking, fracturing, cracking, delamination, indentation, puncturing, drilling, evaporation, ablation and melting.

9. The device of claim 1:

wherein the seal includes a thermal isolation region which reduces a power of the unsealing energy required to damage the seal.

10. The device of claim 1:

wherein the seal includes a region with a power dissipation per unit area which reduces a power of the unsealing energy required to damage the seal.

11. The device of claim 1:

wherein the seal includes a wire and an isolation trench.

12. The device of claim 1:

wherein the seal includes a wire having a meandering shape.

13. The device of claim 1:

further comprising a channel coupling the cavity to the seal;

wherein the channel includes a width an order of magnitude less than a width of the cavity.

14. The device of claim 1:

further comprising a channel coupling a corner of the cavity to the seal.

15. The device of claim 1:

further comprising a channel coupling the cavity to the seal;

wherein the channel includes a main channel and at least one from a group consisting of;

a blocked side channel and a sharp corner.

16. The device of claim 1, wherein:

the MEMS device is a pressure sensor;

the cavity is covered by a membrane; and

the seal is formed from a same material as the membrane.

17. A method calibrating a MEMS device having a seal isolating an internal environment within the MEMS device from an external environment outside the MEMS device, comprising:

measuring a parameter of the internal environment within the MEMS device before damage to the seal;

damaging the seal with a calibration unsealing energy;

wherein upon damage to the seal, a pathway forms which couples the internal environment to the external environment;

measuring a parameter of the internal environment after damage to the seal; and

calibrating the MEMS device based on the measuring.

18. The device of claim 17:

wherein the MEMS device includes a hermetically sealed first device and a calibration device; and

further comprising calibrating the first device in response to measuring the internal environment of the second device before and after damage to the seal on the second device.

19. The method of claim 17, wherein measuring includes:

measuring at least one parameter from a group consisting of;

a cavity pressure, a resonance frequency, a quality factor, a capacitance, a capacitance-voltage response, a capacitance pressure response and a capacitance temperature response.

20. The method of claim 17, wherein measuring includes:

measuring after wafer processing of the MEMS device.

21. The method of claim 17, wherein measuring includes:

measuring after wafer dicing of the MEMS device.

22. The method of claim 17, wherein measuring includes:

measuring after packaging of the MEMS device.

23. The method of claim 17, wherein measuring includes:

measuring after a final assembly of the MEMS device on a printed circuit board in a final application.