Methods and apparatus for particle reduction in MEMS devices

• US 20040222468A1
• Filed: 05/07/2003
• Published: 11/11/2004
• Est. Priority Date: 05/07/2003
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: DCamp, Jon B., Curtis, Harlan L., Glenn, Max C., Dunaway, Lori A.
• Granted Patent: US 6,987,304 B2
• Time in Patent Office: Days
• US Class Current: 257/355
• 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: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis
• CPC Class Codes: G01P 1/023 for acceleration measuring devices

Abstract

A method for assembling a micro-electromechanical system (MEMS) device that includes a micro-machine is described. The method comprises forming the micro-machine on a die, the die having a top surface and a bottom surface, providing a plurality of die bonding pedestals on a surface of a housing, and mounting at least one of the top surface of the die and components of the micro-machine to the die bonding pedestals such that a bottom surface of the die at least partially shields components of the micro-machine from loose gettering material.

Claims

1. A method for assembling a micro-electromechanical system (MEMS) device, the device including a micro-machine, said method comprising:

forming the micro-machine on a die, the die having a top surface and a bottom surface;

providing a plurality of die bonding pedestals on a surface of a housing; and

mounting at least one of the top surface of the die and components of the micro-machine to the die bonding pedestals such that a bottom surface of the die at least partially shields components of the micro-machine from loose gettering material.

2. A method according to claim 1 wherein said mounting comprises mounting the die such that the bottom surface of the die is between the getter and a proof mass, a motor drive comb, a motor pick-off comb, and a sense plate.

3. A method according to claim 1 further comprising providing electrical connections to the components of the micro-machine through the die bonding pedestals.

4. A method according to claim 3 further comprising providing electrical conductors from the die bonding pedestals to an exterior of the housing.

5. A method according to claim 1 wherein said mounting comprises attaching the micromachine to the die bonding pedestals using a thermocompression bonding process.

6. A micro-electromechanical system (MEMS) device comprising:

a micro-machine comprising a die and at least one each of a proof mass, a motor drive comb, a motor pick-off comb, and a sense plate;

a housing for said micro-machine;

a cover configured to be attached to said housing, said cover and said housing forming a substantially sealed cavity; and

a getter within the substantially sealed cavity, said micro machine attached to said housing such that said die shields said proof mass, said motor drive comb, said motor pick-off comb, and said sense plate from particles that become dislodged from said getter.

7. A MEMS device according to claim 6 further comprising a plurality of die bonding pedestals said micro-machine attached to said die bonding pedestals.

8. A MEMS device according to claim 7 wherein said micro-machine is attached to said die bonding pedestals utilizing a thermocompression bonding process.

9. A MEMS device according to claim 6 comprising a plurality of electrical conductors passing through said housing, said die bonding pedestals in contact with said electrical conductors.

10. A MEMS device according to claim 6 wherein said MEMS device is one of a gyroscope, an accelerometer, an inertial measurement unit, a pressure sensor, a resonator, an air flow sensor, and a temperature sensor.

11. A micro-electromechanical system (MEMS) gyroscope comprising:

a housing;

a micro-machine comprising a die, at least one sense plate, at least one proof mass suspended a distance from said at least one sense plate, at least one motor drive comb and at least one motor pick-off comb;

a getter comprising gettering material; and

a cover attached to said housing, said cover and said housing configured to form a substantially sealed cavity for said micro-machine and said getter, said die mounted within the cavity such that gettering material that becomes dislodged from said getter is substantially blocked from contacting said sense plates, said proof masses, said motor drive combs, and said motor pick-off combs.

12. A MEMS gyroscope according to claim 11 further comprising a plurality of die bonding pedestals attached to said housing, said micro-machine attached to said die bonding pedestals.

13. A MEMS gyroscope according to claim 12 wherein at least a portion of electrical connections to said die, said sense plates, said proof masses, said motor drive combs, and said motor pick-off combs are made through said plurality of die bonding pedestals.

14. A MEMS gyroscope according to claim 12 wherein said housing comprises at least one electrical conductor passing through said housing, said electrical conductor in contact with one of said die bonding pedestals.

15. A MEMS gyroscope according to claim 11 wherein a bottom surface of said die is between said getter and said proof masses, said motor drive combs, said motor pick-off combs, and said sense plates.

16. A method for mounting a micro-machine portion of a micro-electromechanical system (MEMS) within a housing portion of the MEMS which also contains a getter, said method comprising:

forming the micro-machine on a die; and

orienting the micro-machine within the housing such that the die is between the getter and components of the micro-machine.

17. A method according to claim 16 wherein mounting the micro-machine within the housing comprises mounting the micro-machine on die bonding pedestals within the housing.

18. A micro-electromechanical system (MEMS) accelerometer comprising:

a housing;

a micro-machine comprising a die, at least one sense plate, at least one proof mass suspended a distance from said at least one sense plate, at least one motor drive comb and at least one motor pick-off comb;

a getter comprising gettering material; and

a cover attached to said housing, said cover and said housing configured to form a substantially sealed cavity for said micro-machine and said getter, said die mounted within the cavity such that gettering material that becomes dislodged from said getter is substantially blocked from contacting said sense plates, said proof masses, said motor drive combs, and said motor pick-off combs.

19. A MEMS accelerometer according to claim 18 further comprising a plurality of die bonding pedestals attaching said housing to said micro-machine.

20. A MEMS accelerometer according to claim 19 wherein at least a portion of electrical connections to said die, said sense plates, said proof masses, said motor drive combs, and said motor pick-off combs are made through said plurality of die bonding pedestals.

21. A MEMS accelerometer according to claim 19 wherein said housing comprises at least one electrical conductor passing through said housing, said electrical conductor in contact with one of said die bonding pedestals.