Laterally integrated MEMS sensor device with multi-stimulus sensing

• US 8,387,464 B2
• Filed: 11/30/2009
• Issued: 03/05/2013
• Est. Priority Date: 11/30/2009
• Status: Active Grant

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Inventors: McNeil, Andrew C., Lin, Yizhen, Park, Woo Tae
• Primary Examiner(s): Noori, Max
• Application Number:
  US12/627,679
• Publication Number:
  US 20110126632A1
• Time in Patent Office: 1,191 Days
• Field of Search: 737/15, 737/18, 737/24, 737/77
• US Class Current: 73/718
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 2201/0264 Pressure sensors
• CPC Class Codes: B81B 7/02 containing distinct electrical or optical devices of particular relevance for their function, e.g. microelectro-mechanical systems [MEMS] B81B7/04 takes precedence
• CPC Class Codes: G01L 19/0092 Pressure sensor associated with other sensors, e.g. for measuring acceleration or temperature G01L9/025, G01L9/045, G01L9/065, G01L9/085, G01L9/105, G01L9/125, G01L19/02, G01L19/04 take precedence; measuring two or more variable G01D21/02; temperature sensors with pressure compensation G01K1/26
• CPC Class Codes: G01L 19/0618 Overload protection
• CPC Class Codes: G01L 9/0047 Diaphragm with non uniform thickness, e.g. with grooves, bosses or continuously varying thickness
• CPC Class Codes: G01L 9/0073 using a semiconductive diaphragm
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 2015/0837 the mass being suspended so as to only allow movement perpendicular to the plane of the substrate, i.e. z-axis sensor
• CPC Class Codes: G01P 2015/088 for providing wafer-level encapsulation
• CPC Class Codes: Y10T 29/49002 Electrical device making

Abstract

A microelectromechanical systems (MEMS) sensor device (20) includes a substrate (22) having sensors (24, 26) disposed on the same side (28) of the substrate (22) and laterally spaced apart from one another. The sensor (26) includes a sense element (56), and the substrate (22) includes a cavity (58) extending through the substrate (22) from the backside (30) of the substrate (22) to expose the sense element (56) to an external environment (54). The sense element (56) is movable in response to a stimulus (52) from the environment (54) due to its exposure to the environment (54) via the cavity (58). Fabrication methodology (66) entails concurrently forming the sensors (24, 26) on substrate (22) by implementing MEMS process flow, followed by creating the cavity (58) through the substrate (22) to expose the sense element (56) to the environment (54).

Claims

1. A microelectromechanical systems (MEMS) sensor device comprising:

a substrate having a first side and a second side that opposes said first side;

a first sensor disposed on said first side of said substrate at a first location;

a second sensor disposed on said first side of said substrate at a second location, said second sensor including a sense element, and said substrate including a cavity at said second location and extending through said substrate from said second side to expose said sense element to an environment external to said MEMS sensor device; and

a cap coupled with said first side of said substrate to form a hermetically sealed chamber in which both of said first sensor and said second sensor are located.

2. A MEMS sensor device as claimed in claim 1 wherein said second sensor comprises a pressure sensor, and said sense element is a diaphragm that is movable in response to a pressure stimulus from said environment.

3. A MEMS sensor device as claimed in claim 2 wherein said first sensor comprises an inertial sensor configured to sense a motion stimulus.

4. A MEMS sensor device as claimed in claim 1 wherein:

said hermetically sealed chamber exhibits a chamber pressure that is variable in response to an ambient temperature and said pressure stimulus;

said second sensor is a pressure sensor and said sense element is a diaphragm that is moveable in response to said pressure stimulus to produce a pressure output signal; and

said MEMS sensor device further comprises a correction circuit in communication with said pressure sensor for receiving said pressure output signal and producing a corrected pressure signal to compensate for an error signal component in said pressure output signal.

5. A MEMS sensor device as claimed in claim 1 wherein:

said sense element is configured to move in a direction perpendicular to said first side of said substrate; and

said second sensor further includes an over-travel stop structure spaced apart from said first side and overlying said sense element, said over-travel stop structure being adapted to limit movement of said sense element in said direction perpendicular to said first side of said substrate.

6. A MEMS sensor device as claimed in claim 1 wherein:

said sense element is configured to move in a direction perpendicular to said first side of said substrate; and

said second sensor further includes a reference element spaced apart from said first side and overlying said sense element, said second sensor being adapted to sense a physical stimulus from said environment as movement of said sense element relative to said reference element in said direction.

7. A MEMS sensor device as claimed in claim 6 wherein said reference element comprises an over-travel stop adapted to limit movement of said sense element in said direction perpendicular to said first side of said substrate.

8. A MEMS sensor device as claimed in claim 6 further comprising a support interposed between said reference element and said sense element and coupled to each of said reference element and said sense element.

9. A MEMS sensor device as claimed in claim 6 wherein said first sensor comprises a movable element in movable communication with said first side of said substrate, said reference element and said movable element being concurrently formed from a common material layer.

10. A MEMS sensor device as claimed in claim 1 wherein said first sensor comprises an electrode element disposed on said first side of said substrate at said first location, said sense element and said electrode element being concurrently formed on said first side from a common material layer.

11. A MEMS sensor device as claimed in claim 1 wherein each of said first and second sensors is a capacitive sensor.

12. A method of producing a microelectromechanical systems (MEMS) sensor device comprising:

concurrently forming an electrode element and a sense element from a first material layer on a first side of a substrate, said electrode element positioned at a first location on said first side and said sense element laterally spaced apart from said electrode element and positioned at a second location on said first side;

concurrently forming a movable element and a reference element spaced apart from said first side of said substrate, said movable element and said reference element being formed from a second material layer, said movable element functioning cooperatively with said electrode element to produce a first sensor, and said reference element overlying said sense element to produce a second sensor; and

creating a cavity at said second location extending through said substrate from a second side of said substrate to expose said sense element to an environment external to said sensor system.

13. A method as claimed in claim 12 wherein:

said forming said electrode element and said sense element include depositing said first material layer over said first side of said substrate and selectively etching said first material layer to produce said electrode element and said sense element; and

said forming said movable element and said reference element includes depositing a sacrificial layer over said electrode element and said sense element, selectively etching said sacrificial layer, depositing said second material layer over said sacrificial layer, selectively etching said second material layer to produce said movable element and said reference element, and removing said sacrificial layer to form respective first and second sensors.

14. A method as claimed in claim 12 further comprising coupling a cap to said first side of said substrate to form a hermetically sealed chamber in which both of said first sensor and said second sensor are located.

15. A method as claimed in claim 14 wherein:

said first sensor comprises an inertial sensor and said movable element moves relative to said electrode element in response to a motion stimulus; and

said second sensor comprises a pressure sensor and said sense element moves relative to said reference element in response to a pressure stimulus from said environment.

16. A microelectromechanical systems (MEMS) sensor device comprising:

a substrate having a first side and a second side that opposes said first side;

a first sensor disposed on said first side at a first location;

a second sensor disposed on said first side at a second location, said second sensor comprising a pressure sensor having a diaphragm, and said substrate including a cavity at said second location, said cavity extending through said substrate from said second side to expose said diaphragm to an environment external to said MEMS sensor device, and said diaphragm being movable in response to a pressure stimulus from said environment; and

a cap coupled with said first side of said substrate to form a hermetically sealed chamber in which both of said first sensor and said pressure sensor are located.

17. A MEMS sensor device as claimed in claim 16 wherein:

said diaphragm is configured to move in a direction perpendicular to said first side of said substrate; and

said pressure sensor further includes a reference element spaced apart from said first side and overlying said diaphragm, said pressure sensor being adapted to sense said pressure stimulus from said environment as movement of said diaphragm relative to said reference element in said direction.

18. A MEMS sensor device as claimed in claim 17 wherein said first sensor comprises a movable element in movable communication with said first side of said substrate, said reference element and said movable element being concurrently formed from a common material layer.

19. A MEMS sensor device as claimed in claim 16 wherein said first sensor comprises an electrode element disposed on said first side of said substrate at said first location, said diaphragm and said electrode element being concurrently formed on said first side from a common material layer.