Device containing plurality of smaller MEMS devices in place of a larger MEMS device

• US 8,861,218 B2
• Filed: 11/09/2009
• Issued: 10/14/2014
• Est. Priority Date: 11/07/2008
• Status: Active Grant

• Current Assignee: Qorvo US, Inc. (Qorvo, Inc.)
• Original Assignee: Cavendish Kinetics Inc (Qorvo, Inc.)
• Inventors: Smith, Charles Gordon, Knipe, Richard L., Joshi, Vikram, Unamuno, Anartz, Gaddi, Roberto, Van Kampen, Robertus Petrus
• Primary Examiner(s): Dinh, Tuan T
• Application Number:
  US12/614,929
• Publication Number:
  US 20100116632A1
• Time in Patent Office: 1,800 Days
• Field of Search: 257415-417, 257/528, 200180-182, 361782-784, 361760-766
• US Class Current: 361/763
• CPC Class Codes: B81B 2201/0221 Variable capacitors
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 2207/053 of movable structures
• CPC Class Codes: B81B 7/04 Networks or arrays of similar microstructural devices
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 15/135 by making use of contacts which are actuated by a movable inertial mass
• CPC Class Codes: H01G 5/18 due to change in inclination, e.g. by flexing, by spiral wrapping
• CPC Class Codes: H01G 5/40 Structural combinations of variable capacitors with other electric elements not covered by this subclass, the structure mainly consisting of a capacitor, e.g. RC combinations

Abstract

Embodiments disclosed herein generally include using a large number of small MEMS devices to replace the function of an individual larger MEMS device or digital variable capacitor. The large number of smaller MEMS devices perform the same function as the larger device, but because of the smaller size, they can be encapsulated in a cavity using complementary metal oxide semiconductor (CMOS) compatible processes. Signal averaging over a large number of the smaller devices allows the accuracy of the array of smaller devices to be equivalent to the larger device. The process is exemplified by considering the use of a MEMS based accelerometer switch array with an integrated analog to digital conversion of the inertial response. The process is also exemplified by considering the use of a MEMS based device structure where the MEMS devices operate in parallel as a digital variable capacitor.

Claims

1. A device structure, comprising:

a substrate;

a plurality of layers formed over the substrate, a first layer of the plurality of layers bounding one or more cavities formed within the structure between the substrate and the plurality of layers;

a plurality of micro electromechanical devices disposed over the substrate and within each of the one or more cavities;

a pull up electrode within at least one of the one or more cavities and coupled with the first layer above the plurality of micro electromechanical devices; and

a via connection from the substrate to one or more layers disposed over the one or more cavities;

wherein the one or more cavities and plurality of micro electromechanical devices are embedded within a complementary metal oxide semiconductor; and

wherein a first device of the plurality of devices has a different design than a second device of the plurality of devices.

2. The device structure of claim 1, wherein at least one of the one or more cavities has a length, a width and a height where at least one of the length or width is between about 20 microns and about 30 microns.

3. A device structure, comprising:

a substrate;

a plurality of layers formed over the substrate, a first layer of the plurality of layers bounding one or more cavities formed within the structure between the substrate and the plurality of layers;

a plurality of micro electromechanical devices disposed over the substrate and within each of the one or more cavities;

a pull up electrode within at least one of the one or more cavities and coupled with the first layer above the plurality of micro electromechanical devices;

a via connection from the substrate to one or more layers disposed over the one or more cavities;

a first electrode;

a second electrode; and

a plurality of cantilevers that are each movable from a position in contact with the first electrode to a position spaced from both the first electrode and the second electrode to a position in contact with the second electrode.

4. The device structure of claim 3, wherein the device structure is a digital variable capacitor.

5. The device structure of claim 4, further comprising a third electrode, wherein each of the plurality of cantilevers is coupled to the third electrode.

6. A device structure, comprising:

a substrate;

a layer formed over the substrate and bounding a cavity formed within the structure;

a plurality of micro electromechanical devices disposed within the cavity;

a pull up electrode within the cavity and coupled with the layer;

a via connection from the substrate to layer;

a first electrode;

a second electrode; and

a plurality of cantilevers that are each movable from a position in contact with the first electrode to a position spaced from both the first electrode and the second electrode to a position in contact with the second electrode, wherein;

the cavity has a length, a width and a height where at least one of the length or width is between about 20 microns and about 30 microns;

the cavity and plurality of micro electromechanical devices are embedded within a complementary metal oxide semiconductor; and

a first device of the plurality of devices has a different design than a second device of the plurality of devices.

7. The device structure of claim 6, wherein the device structure is a digital variable capacitor.

8. The device structure of claim 7, further comprising a third electrode, wherein each of the plurality of cantilevers is coupled to the third electrode.

9. A device structure, comprising:

a substrate;

a layer formed over the substrate and bounding a cavity formed within the structure;

a plurality of micro electromechanical devices disposed within the cavity;

a pull up electrode within the cavity and coupled with the layer;

a via connection from the substrate to layer;

a first electrode;

a second electrode; and

a plurality of cantilevers that are each movable from a position in contact with the first electrode to a position spaced from both the first electrode and the second electrode to a position in contact with the second electrode.

10. The device structure of claim 9, wherein the device structure is a digital variable capacitor.

11. The device structure of claim 9, further comprising a third electrode, wherein each of the plurality of cantilevers is coupled to the third electrode.

12. The device structure of claim 10, further comprising a third electrode, wherein each of the plurality of cantilevers is coupled to the third electrode.