MEMS PRESSURE TRANSDUCER ASSEMBLY

• US 20140339656A1
• Filed: 08/04/2014
• Published: 11/20/2014
• Est. Priority Date: 02/21/2012
• Status: Active Grant

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Inventors: Schlarmann, Mark E., Lin, Yizhen
• Granted Patent: US 9,090,455 B2
• Time in Patent Office: Days
• US Class Current: 257/415
• CPC Class Codes: B81B 2203/0118 Cantilevers
• CPC Class Codes: B81B 2203/0127 Diaphragms, i.e. structures separating two media that can control the passage from one medium to another; Membranes, i.e. diaphragms with filtering function
• CPC Class Codes: B81B 2203/051 Translation according to an axis parallel to the substrate
• CPC Class Codes: B81B 2207/115 Protective layers applied directly to the device before packaging
• CPC Class Codes: B81B 3/0021 Transducers for transforming electrical into mechanical energy or vice versa dynamo-electric machines H02K99/00; electrostatic machines H02N1/00; piezoelectric devices H10N30/00
• CPC Class Codes: B81B 3/0072 For controlling internal stress or strain in moving or flexible elements, e.g. stress compensating layers
• CPC Class Codes: B81B 7/0048 between the MEMS die and the substrate
• CPC Class Codes: B81B 7/0058 for protecting against damages due to external chemical or mechanical influences, e.g. shocks or vibrations
• CPC Class Codes: B81C 1/00309 suitable for fluid transfer from the MEMS out of the package or vice versa, e.g. transfer of liquid, gas, sound
• CPC Class Codes: G01L 19/147 Details about the mounting of the sensor to support or covering means
• CPC Class Codes: G01L 9/0042 Constructional details associated with semiconductive diaphragm sensors, e.g. etching, or constructional details of non-semiconductive diaphragms details about the integration or bonding of piezoresistor in or on the diaphragm G01L9/0052 and G01L9/0057 respectively
• CPC Class Codes: G01L 9/0052 of piezoresistive elements circuits therefor G01L9/06
• CPC Class Codes: H01L 2224/48137 the bodies being arranged next to each other, e.g. on a common substrate

Abstract

An assembly (20) includes a MEMS die (22) having a pressure transducer device (40) formed on a substrate (44) and a cap layer (38). A packaging process (74) entails forming the device (40) on the substrate, creating an aperture (70) through a back side (58) of the substrate underlying a diaphragm (46) of the device (40), and coupling a cap layer (38) to the front side of the substrate overlying the device. A trench (54) is produced extending through both the cap layer and the substrate, and the trench surrounds a cantilevered platform (48) at which the diaphragm resides. The MEMS die is suspended above a substrate (26) so that a clearance space (60) is formed between the cantilevered platform and the substrate. The diaphragm is exposed to an external environment (68) via the aperture, the clearance space, and an external port.

Claims

1. An assembly comprising:

a device structure having a cantilevered platform formed therein, wherein a trench extends through said device structure surrounding said cantilevered platform;

a microelectromechanical systems (MEMS) device formed at a front side of said device structure, said MEMS device having an active region residing on said cantilevered platform, and an aperture extends through said device structure underlying said active region of said MEMS device; and

a cap layer coupled to said front side of said device structure overlying said MEMS device, wherein at least a portion of said cap layer is attached to said cantilevered platform to form a sealed cavity in which said active region is located.

2. The assembly of claim 1 wherein said MEMS device comprises a pressure transducer, said pressure transducer including a movable diaphragm in said active region, said movable diaphragm being exposed to an external environment via said aperture.

3. The assembly of claim 2 wherein said movable diaphragm is movable relative to said cantilevered platform.

4. The assembly of claim 1 wherein said cantilevered platform has a sole attachment point to said device structure surrounding said cantilevered platform.

5. The assembly of claim 1 further comprising a base substrate attached to a back side of said device structure such that a clearance space is formed between said cantilevered platform and said base substrate, said cantilevered platform being suspended above said base substrate.

6. The assembly of claim 5 further comprising an adhesive attaching said back side of said device structure to said base substrate, said adhesive having a thickness sufficient to produce said clearance space underlying said cantilevered platform.

7. The assembly of claim 5 wherein said trench additionally extends through said cap layer surrounding said cantilevered platform, said clearance space and said aperture are in communication with said trench, and said active region is exposed to an external environment via said trench, said clearance space, and said aperture.

8. The assembly of claim 7 further comprising a protective cap over said trench and said cap layer overlying said cantilevered platform, wherein said protective cap includes a port extending through said protective cap to expose said trench to said external environment.

9. The assembly of claim 5 wherein said base substrate includes a cutout in said base substrate to produce said clearance space.

10. The assembly of claim 9 wherein said cutout extends through an entirety of said base substrate so that said active region is exposed to an external environment via said cutout, said clearance space, and said aperture.

11. The assembly of claim 1 wherein said MEMS device includes conductive traces formed at said front side of said device structure, and said cap layer covers said conductive traces such that said conductive traces reside in said sealed cavity.

12. The assembly of claim 11 wherein said sealed cavity is sized to provide a gap between said cap layer and said conductive traces.

13. An assembly comprising:

a device structure having a cantilevered platform formed therein, wherein a trench extends through said device structure surrounding said cantilevered platform, and said cantilevered platform has a sole attachment point to said device structure surrounding said cantilevered platform;

a microelectromechanical systems (MEMS) device formed at a front side of said device structure, said MEMS device having an active region residing on said cantilevered platform, and an aperture extends through said device structure underlying said active region of said MEMS device, wherein said MEMS device comprises a pressure transducer, said pressure transducer including a movable diaphragm in said active region, said movable diaphragm being exposed to an external environment via said aperture; and

a cap layer coupled to said front side of said device structure overlying said MEMS device, wherein at least a portion of said cap layer is attached to said cantilevered platform to form a sealed cavity in which said movable diaphragm is located.

14. The assembly of claim 13 wherein said movable diaphragm is movable relative to said cantilevered platform.

15. The assembly of claim 13 wherein said MEMS device includes conductive traces formed at said front side of said device structure, and said cap layer covers said conductive traces such that said conductive traces reside in said sealed cavity.

16. The assembly of claim 15 wherein said sealed cavity is sized to provide a gap between said cap layer and said conductive traces.

17. An assembly comprising:

a device structure having a cantilevered platform formed therein, wherein a trench extends through said device structure surrounding said cantilevered platform;

a micro electromechanical systems (MEMS) device formed at a front side of said device structure, said MEMS device having an active region residing on said cantilevered platform, and an aperture extends through said device structure underlying said active region of said MEMS device;

a cap layer coupled to said front side of said device structure overlying said MEMS device, wherein said trench additionally extends through said cap layer surrounding said cantilevered platform, and at least a portion of said cap layer is attached to said cantilevered platform to form a sealed cavity in which said active region is located; and

a base structure attached to a back side of said device structure such that a clearance space is formed between said cantilevered platform and said base structure, said cantilevered platform being suspended above said base structure.

18. The assembly of claim 17 wherein said MEMS device comprises a pressure transducer, said pressure transducer including a movable diaphragm in said active region, said movable diaphragm being movable relative to said cantilevered platform, and said movable diaphragm being exposed to an external environment via said aperture.

19. The assembly of claim 17 wherein said clearance space and said aperture are in communication with said trench, and said active region is exposed to an external environment via said trench, said clearance space, and said aperture.

20. The assembly of claim 17 wherein said base structure includes a cutout extending through an entirety of said base structure so that said active region is exposed to an external environment via said cutout, said clearance space, and said aperture.