Embedded microelectromechanical systems sensor and related devices and methods

• US 8,610,223 B2
• Filed: 07/27/2011
• Issued: 12/17/2013
• Est. Priority Date: 01/27/2009
• Status: Active Grant

• Current Assignee: Arizona Board of Regents (University of Arizona)
• Original Assignee: Arizona Board of Regents (University of Arizona)
• Inventors: Lakamraju, Narendra V., Venugopal, Sameer M., Phillips, Stephen M., Allee, David R.
• Primary Examiner(s): Nguyen, Thinh T
• Application Number:
  US13/192,261
• Publication Number:
  US 20120175714A1
• Time in Patent Office: 874 Days
• Field of Search: 257/415, 257/E27.006, 257/E21.002, 257/88, 257/417, 257/419, 438/24, 438/53, 438/50, 438/51
• US Class Current: 257/415
• CPC Class Codes: G01L 19/083 electrical
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes

Abstract

Embodiments of embedded MEMS sensors and related methods are described herein. Other embodiments and related methods are also disclosed herein.

Claims

1. A semiconductor device comprising:

a flexible substrate; and

a MEMS device fabricated over the flexible surface;

wherein;

the MEMS device comprises;

an electrically conductive material located over the flexible substrate;

a sensor membrane movably suspended over the electrically conductive material;

a first dielectric located over the electrically conductive material and under the sensor membrane; and

a wall structure coupled to the first dielectric;

and

the sensor membrane is suspended by the wall structure over the electrically conductive material.

2. The semiconductor device of claim 1 further comprising at least one of:

a planarization layer between the flexible substrate and the MEMS device;

an electronic device fabricated over the flexible substrate and electrically coupled to the MEMS device;

or

two or more MEMS sensors electrically coupled in parallel with each other, wherein one of the two or more MEMS sensors comprises the MEMS device.

3. The semiconductor device of claim 2 wherein:

when the semiconductor device comprises the electronic device, at least one of;

the electronic device comprises at least one of a display element or a capacitance measurement circuit;

or

the electronic device is configured to process blast dosimetry information measured via the MEMS device.

4. The semiconductor device of claim 1 wherein:

the flexible substrate comprises at least one of;

a PEN material, a PET material, a PES material, a polyimide, a polycarbonate, a cyclic olefin copolymer, a liquid crystal polymer, a stainless steel material, a FeNi alloy material, a FeNiCo alloy material, a titanium material, a tantalum material, a molybdenum material, an aluchrome material, or an aluminum material.

5. The semiconductor device of claim 1 wherein at least one of:

the electrically conductive material comprises at least one of molybdenum, tantalum, aluminum, tungsten, or gold;

the sensor membrane is configured to move toward the first dielectric when deformed by at least one of a shock wave or a pressure change;

or

the sensor membrane is substantially circular.

6. The semiconductor device of claim 1 wherein:

the MEMS device further comprises a compartment between the electrically conductive material and the sensor membrane.

7. The semiconductor device of claim 6 wherein at least one of:

the sensor membrane comprises between approximately 5 openings to approximately 20 openings into the compartment;

or

the compartment defines an air gap between the electrically conductive material and the sensor membrane.

8. The semiconductor device of claim 7 wherein:

the sensor membrane comprises;

a second electrically conductive material facing the first dielectric; and

a support layer located over the second electrically conductive material and anchored at a perimeter of the sensor membrane.

9. The semiconductor device of claim 8 wherein at least one of:

the second electrically conductive material comprises at least one of aluminum, tantalum, molybdenum, tungsten, or gold;

the support layer comprises at least one of a silicon nitride material, a silicon oxynitride material, a silicon dioxide material, a passivation material, a siloxane-based material, an organosiloxane material, an organic siloxane-based material, or a PTS material;

or

the support layer comprises a thickness of between approximately 2 micrometers to approximately 2.5 micrometers.

10. The semiconductor device of claim 1 wherein:

the wall structure comprises one or more dielectric layers located over the first dielectric along a sensor perimeter of the MEMS device.

11. The semiconductor device of claim 1 further comprising at least one of:

a first electronic device fabricated over the flexible substrate and electrically coupled to the MEMS device, wherein the first electronic device comprises at least one first transistor and the electrically conductive material comprises a gate electrode material used for a gate electrode of the at least one first transistor of the first electronic device;

or

a second electronic device fabricated over the flexible substrate and electrically coupled to the MEMS device, wherein the second electronic device comprises at least one second transistor and the first dielectric comprises a gate dielectric material used for a gate dielectric of the at least one second transistor of the second electronic device.

12. A semiconductor device comprising:

a flexible substrate; and

a MEMS device fabricated over the flexible surface;

wherein at least one of;

the MEMS device comprises a circular perimeter with a radius of between approximately 50 micrometers to approximately 250 micrometers;

the MEMS device comprises a height of between approximately 2.5 micrometers to approximately 3.5 micrometers;

or

the MEMS device comprises a steady state capacitance of between approximately 1.5 picofarads to approximately 8.0 picofarads.

13. A method comprising:

providing a flexible substrate; and

fabricating a first MEMS device over the flexible substrate;

wherein;

fabricating the first MEMS device comprises;

providing an electrically conductive material layer located over the flexible substrate;

providing a sensor membrane configured to be movably suspended over the electrically conductive material layer;

providing a first dielectric located over the electrically conductive material layer and under the sensor membrane; and

providing a wall structure coupled to the first dielectric;

and

the sensor membrane is configured to be suspended by the wall structure over the electrically conductive material layer.

14. The method of claim 13, wherein:

fabricating the first MEMS device comprises;

providing a sacrificial structure over the electrically conductive material layer; and

providing the sensor membrane over the sacrificial structure.

15. The method of claim 14 wherein at least one of:

providing the flexible substrate comprises providing the flexible substrate to comprise at least one of a PEN material, a PET material, a PES material, a polyimide, a polycarbonate, a cyclic olefin copolymer, or a liquid crystal polymer;

the sacrificial structure comprises an amorphous silicon material;

providing the sensor membrane comprises providing the sensor membrane to comprise a substantially circular perimeter;

fabricating the first MEMS device comprises forming the first MEMS device at temperatures not exceeding approximately 190 degrees Celsius;

or

fabricating the first MEMS device further comprises providing the first dielectric between the electrically conductive material layer and the sacrificial structure.

16. The method of claim 14 wherein:

providing the sacrificial structure comprises;

providing a sacrificial layer over the electrically conductive material layer.

17. The method of claim 16 wherein:

providing the sacrificial structure comprises providing a compartment wall of the wall structure at a perimeter of the sacrificial layer and over the electrically conductive material layer, the compartment wall comprising one or more dielectric layers;

providing the compartment wall comprises providing a perimeter of at least one of the one or more dielectric layers of the compartment wall to couple with the first MEMS device past a perimeter of the sacrificial layer; and

the one or more dielectric layers over the sacrificial layer comprise at least one of an intermetal dielectric material, a passivation material, or a silicon nitride material.

18. The method of claim 16 further comprising:

etching one or more openings through the sensor membrane to expose one or more portions of the sacrificial layer; and

removing the sacrificial layer via the one or more openings of the sensor membrane.

19. The method of claim 18 wherein:

removing the sacrificial layer comprises dry etching the sacrificial layer through the one or more openings of the sensor membrane; and

dry etching the sacrificial layer comprises using at least one of a dry etch reactant, a gaseous reactant, or an XeF₂ reactant.

20. The method of claim 14 wherein:

providing the sensor membrane comprises;

providing a second electrically conductive material layer over the sacrificial structure; and

providing a structural layer over the second electrically conductive material layer.

21. The method of claim 20 wherein at least one of:

providing the structural layer comprises providing a perimeter of the structural layer to couple with a perimeter of the sacrificial structure past a perimeter of the second electrically conductive material layer;

providing the sensor membrane further comprises etching one or more openings through the second electrically conductive material layer to expose one or more portions of the sacrificial structure prior to providing the structural layer;

the second electrically conductive material layer comprises at least one of an aluminum material, a tantalum material, a molybdenum material, a tungsten material, or a gold material;

the structural layer comprises at least one of a silicon nitride material, a silicon oxynitride material, a silicon dioxide material, a passivation material, a siloxane-based material, an organosiloxane material, an organic siloxane-based material, or a PTS material;

or

providing the sensor membrane further comprises etching one or more openings through the structural layer to expose at least a portion of the sacrificial structure.

22. The method of claim 14 further comprising:

forming over the flexible substrate an electronic device electrically coupled to the first MEMS device;

wherein the electronic device comprises at least one of;

a display element;

or

a capacitance measurement circuit.

23. The method of claim 22 wherein at least one of:

the first MEMS device is fabricated pursuant to at least one of;

(1) a semiconductor process flow for the electronic device or (2) a modification of the semiconductor process flow for the electronic device;

providing the electrically conductive material layer comprises simultaneously providing the electrically conductive material layer and a gate electrode for a transistor of the electronic device;

providing the sensor membrane comprises providing at least a portion of the sensor membrane simultaneously with a channel material of a transistor of the electronic device;

or

forming the electronic device comprises providing a gate dielectric of a transistor of the electronic device simultaneously with a dielectric of the first MEMS device.