Method of producing a microelectromechanical (MEMS) sensor device

• US 8,216,882 B2
• Filed: 08/23/2010
• Issued: 07/10/2012
• Est. Priority Date: 08/23/2010
• Status: Expired due to Fees

• Current Assignee: North Star Innovations Inc. (Wi-LAN Inc.)
• Original Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Inventors: Lin, Yizhen, Park, Woo Tae, Schlarmann, Mark E., Desai, Hemant D.
• Primary Examiner(s): Dang, Phuc
• Application Number:
  US12/861,509
• Publication Number:
  US 20120043627A1
• Time in Patent Office: 687 Days
• Field of Search: 438/113, 438/114, 257/415, 257/416, 257/417, 257/E29.001
• US Class Current: 438/113
• CPC Class Codes: B81B 2201/025 Inertial sensors not provided for in B81B2201/0235 - B81B2201/0242
• 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 9/0073 using a semiconductive diaphragm
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 2015/0814 for translational movement of the mass, e.g. shuttle type
• CPC Class Codes: G01P 2015/088 for providing wafer-level encapsulation
• CPC Class Codes: H01G 5/18 due to change in inclination, e.g. by flexing, by spiral wrapping
• CPC Class Codes: H01L 28/60 Electrodes

Abstract

A device (20, 90) includes sensors (28, 30) that sense different physical stimuli. A pressure sensor (28) includes a reference element (44) and a sense element (52), and an inertial sensor (30) includes a movable element (54). Fabrication (110) entails forming (112) a first substrate structure (22, 92) having a cavity (36, 100), forming a second substrate structure (24) to include the sensors (28, 30), and coupling (128) the substrate structures so that the first sensor (28) is aligned with the cavity (36, 100) and the second sensor (30) is laterally spaced apart from the first sensor (28). Forming the second structure (24) includes forming (118) the sense element (52) from a material layer (124) of the second structure (24) and following coupling (128) of the substrate structures, concurrently forming (132) the reference element (44) and the movable element (54) in a wafer substrate (122) of the second structure (24).

Claims

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

forming a first substrate structure having a cavity;

forming at least a portion of a second substrate structure to include a first sensor and a second sensor laterally spaced apart from said first sensor;

coupling said second substrate structure with said first substrate structure such that said first sensor is aligned with said cavity; and

attaching a cap to said second substrate structure such that said first and second sensors are interposed between said cap and said first substrate structure, wherein said first sensor is exposed to an environment external to said MEMS sensor device via one of a group consisting of said cavity and said cap.

2. A method as claimed in claim 1 wherein said forming said second substrate structure comprises:

forming a sense element of said first sensor from a material layer of said second substrate structure; and

concurrently forming a reference element of said first sensor and a movable element of said second sensor in a wafer substrate of said second substrate structure following said coupling step.

3. A method as claimed in claim 2 wherein:

said first sensor is a pressure sensor, and said sense element is a diaphragm interposed between said cavity and said reference element, said diaphragm being movable relative to said reference element in response to a pressure stimulus from said environment; and

said second sensor is an inertial sensor adapted to sense a motion stimulus as movement of said movable element relative to a fixed element of said second sensor.

4. A method as claimed in claim 2 further comprising forming an electrode element of said second sensor from said material layer of said second substrate structure, said electrode element being formed concurrent with said sense element of said first sensor.

5. A method as claimed in claim 4 wherein said forming said sense element and said electrode element includes producing each of said sense and electrode elements having a first thickness that is less than a second thickness of said wafer substrate.

6. A method as claimed in claim 2 wherein:

said forming said sense element comprises depositing a sacrificial layer on a surface of said wafer substrate, depositing said material layer on said sacrificial layer, and selectively removing a portion of said material layer to produce said sense element; and

said method further comprises following said coupling operation, removing said sacrificial layer between said wafer substrate and said sense element to produce a gap between said reference element and said sense element and removing said sacrificial layer contacting said movable element to enable movement of said movable element.

7. A method as claimed in claim 1 wherein said cap includes a first chamber and a second chamber, said second chamber being physically isolated from said first chamber, and said attaching including arranging said cap on said second substrate structure such that said first sensor resides in said first chamber of said cap and said second sensor resides in said second chamber of said cap.

8. A method as claimed in claim 7 wherein said cap includes a port extending through said cap to expose said first chamber to said environment external to said MEMS sensor device, said forming said first substrate structure produces said cavity having a depth that is less than a thickness of said first substrate structure, and said first sensor is exposed to said environment via said port extending through said cap.

9. A method as claimed in claim 7 wherein said forming said first substrate structure produces said cavity extending through a thickness of said first substrate structure, said first chamber of said cap is a hermetically sealed chamber in which said first sensor resides, and said first sensor is exposed to said environment via said cavity.

10. A method as claimed in claim 7 wherein said second chamber of said cap is a hermetically sealed chamber in which said second sensor resides.

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

forming a first substrate structure having a cavity;

forming at least a portion of a second substrate structure to include a first sensor and a second sensor laterally spaced apart from said first sensor, said forming said at least a portion of said second substrate structure including forming a sense element of said first sensor from a material layer of said second substrate structure;

coupling said second substrate structure with said first substrate structure such that said sense element is aligned with said cavity;

following said coupling operation, concurrently forming a reference element of said first sensor and a movable element of said second sensor in a wafer substrate of said second substrate structure, said reference element being aligned with said sense element such that said sense element is interposed between said cavity and said reference element; and

attaching a cap to said second substrate structure such that said first and second sensors are interposed between said cap and said first substrate structure, said cap having a first chamber and a second chamber, said second chamber being physically isolated from said first chamber, and said attaching including arranging said cap such that said first sensor resides in said first chamber and said second sensor resides in said second chamber, wherein said first sensor is exposed to an environment external to said MEMS sensor device via one of a group consisting of said cavity and said cap.

12. A method as claimed in claim 11 wherein:

said first sensor is a pressure sensor, and said sense element is a diaphragm, said diaphragm being movable relative to said reference element in response to a pressure stimulus from said environment; and

said second sensor is an inertial sensor adapted to sense a motion stimulus as movement of said movable element relative to a fixed element of said second sensor.

13. A method as claimed in claim 11 wherein said cap includes a port extending through said cap to expose said first chamber to said environment external to said MEMS sensor device, said forming said first substrate structure produces said cavity having a depth that is less than a thickness of said first substrate structure, and said first sensor is exposed to said environment via said port extending through said cap.

14. A method as claimed in claim 11 wherein said forming said first substrate structure produces said cavity extending through a thickness of said first substrate structure, said first chamber of said cap is a hermetically sealed chamber in which said first sensor resides, and said first sensor is exposed to said environment via said cavity.

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

forming a first substrate structure having a cavity;

forming at least a portion of a second substrate structure to include a first sensor and a second sensor laterally spaced apart from said first sensor, said forming said second substrate structure including;

forming a sense element of said first sensor from a material layer of said second substrate structure;

forming an electrode element of said second sensor from said material layer of said second substrate structure, said electrode element being formed concurrent with said sense element of said first sensor, wherein said forming said sense element and said electrode element includes depositing a sacrificial layer on a surface of said wafer substrate, depositing said material layer on said sacrificial layer, and selectively removing a portion of said material layer to produce said sense element and said electrode element; and

concurrently forming a reference element of said first sensor and a movable element of said second sensor in a wafer substrate of said second substrate structure following said coupling step;

coupling said second substrate structure with said first substrate structure such that said first sensor is aligned with said cavity;

following said coupling operation, removing said sacrificial layer between said wafer substrate and said sense element to produce a gap between said reference element and said sense element and removing said sacrificial layer contacting said movable element to enable movement of said movable element; and

attaching a cap to said second substrate structure such that said first and second sensors are interposed between said cap and said first substrate structure, wherein said first sensor is exposed to an environment external to said MEMS sensor device via one of a group consisting of said cavity and said cap.

16. A method as claimed in claim 15 wherein said forming said sense element and said electrode element includes producing each of said sense and electrode elements having a first thickness that is less than a second thickness of said wafer substrate.

17. A method as claimed in claim 15 wherein said cap includes a first chamber and a second chamber, said second chamber being physically isolated from said first chamber, and said attaching including arranging said cap on said second substrate structure such that said first sensor resides in said first chamber of said cap and said second sensor resides in said second chamber of said cap.

18. A method as claimed in claim 17 wherein:

said cap includes a port extending through said cap to expose said first chamber to said environment external to said MEMS sensor device, said forming said first substrate structure produces said cavity having a depth that is less than a thickness of said first substrate structure, said first sensor being exposed to said environment via said port extending through said cap; and

said second chamber of said cap is a hermetically sealed chamber in which said second sensor resides such that said second sensor is protected from said environment.

19. A method as claimed in claim 17 wherein:

said forming said first substrate structure produces said cavity extending through a thickness of said first substrate structure, said first chamber of said cap is a hermetically sealed chamber in which said first sensor resides, said first sensor being exposed to said environment via said cavity; and

said second chamber of said cap is a hermetically sealed chamber in which said second sensor resides such that said second sensor is protected from said environment.

20. A method as claimed in claim 15 wherein:

said first sensor is a pressure sensor, and said sense element is a diaphragm interposed between said cavity and said reference element, said diaphragm being movable relative to said reference element in response to a pressure stimulus from said environment; and

said second sensor is an inertial sensor adapted to sense a motion stimulus as movement of said movable element relative to a fixed element of said second sensor.