Micro-electro-mechanical device and manufacturing process thereof

• US 10,150,666 B2
• Filed: 05/23/2017
• Issued: 12/11/2018
• Est. Priority Date: 11/19/2015
• Status: Active Grant

• Current Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Baldo, Lorenzo, Duqi, Enri, Villa, Flavio Francesco
• Primary Examiner(s): Gebreyesus, Yosef
• Application Number:
  US15/602,760
• Publication Number:
  US 20170253477A1
• Time in Patent Office: 567 Days
• CPC Class Codes: B81B 2201/0228 Inertial sensors
• CPC Class Codes: B81B 2201/025 Inertial sensors not provided for in B81B2201/0235 - B81B2201/0242
• 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 2203/0163 Spring holders
• CPC Class Codes: B81B 2203/0315 Cavities
• CPC Class Codes: B81B 2207/012 the micromechanical device and the control or processing electronics being separate parts in the same package
• 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 7/0045 for reducing stress inside of the package structure
• CPC Class Codes: B81C 1/00182 Arrangements of deformable or non-deformable structures, e.g. membrane and cavity for use in a transducer
• CPC Class Codes: B81C 1/00325 for reducing stress inside of the package structure
• CPC Class Codes: B81C 2201/0116 Thermal treatment for structural rearrangement of substrate atoms, e.g. for making buried cavities
• CPC Class Codes: B81C 2201/0173 Thermo-migration of impurities from a solid, e.g. from a doped deposited layer
• CPC Class Codes: B81C 2203/0785 Transfer and j oin technology, i.e. forming the electronic processing unit and the micromechanical structure on separate substrates and joining the substrates
• CPC Class Codes: G02B 26/0858 the reflecting means being moved or deformed by piezoelectric means

Abstract

A micro-electro-mechanical device formed in a monolithic body of semiconductor material accommodating a first buried cavity; a sensitive region above the first buried cavity; and a second buried cavity extending in the sensitive region. A decoupling trench extends from a first face of the monolithic body as far as the first buried cavity and laterally surrounds the second buried cavity. The decoupling trench separates the sensitive region from a peripheral portion of the monolithic body.

Claims

1. A micro-electro-mechanical device, comprising:

a monolithic body of semiconductor material;

a first buried cavity in the monolithic body of semiconductor material;

a sensitive region in the monolithic body facing the first buried cavity; and

a decoupling trench extending into the monolithic body as far as the first buried cavity, the decoupling trench decoupling the sensitive region from a peripheral portion of the monolithic body and forming the sensitive region.

2. The device according to claim 1, wherein the monolithic body includes a second buried cavity in the sensitive region, the second buried cavity overlapping the first buried cavity.

3. The device according to claim 1, further comprising a membrane over the sensitive region, the membrane having a perimeter that is coupled to the sensitive region.

4. The device according to claim 3, wherein the membrane is spaced apart from the sensitive region by a cavity.

5. The device according to claim 1, wherein the decoupling trench has a spiral shape that extends around an entire perimeter of the sensitive region.

6. The device according to claim 5, wherein the decoupling trench has a first end portion and a second end portion, the first end portion and the second end portion extending along a same side of the sensitive region.

7. The device according to claim 1, further comprising a cap element coupled to a surface of the peripheral portion of the monolithic body.

8. A micro-electro-mechanical device, comprising:

a monolithic body of semiconductor material;

a buried cavity in the monolithic body of semiconductor material;

a sensitive region in the monolithic body covering the buried cavity; and

a movable element including a central portion and a perimeter portion, the perimeter portion coupled to the sensitive region, the central portion of the movable element being separated from the sensitive region by a second cavity.

9. The device according to claim 8, wherein the movable element is a MEMS inertial sensor that moves in response to acceleration.

10. The device according to claim 8, comprising a decoupling trench having a spiral shape that separates the sensitive region from a peripheral portion of the monolithic body.

11. The device according to claim 10, wherein the decoupling trench has a first end portion and a second end portion, the first end portion and the second end portion extending along a same side of the sensitive region.

12. The device according to claim 10, comprising a cap coupled to the peripheral portion of the monolithic body, the cap forming a cavity with the monolithic body, the movable element being located in the cavity.

13. The device according to claim 8, wherein monolithic body includes a through opening that places the buried cavity in fluid communication with an environment that is external to the micro-electro-mechanical device.

14. An electronic apparatus comprising:

a microprocessor; and

a micro-electro-mechanical device including;

a monolithic body of semiconductor material;

a buried cavity in the monolithic body of semiconductor material;

a sensitive region in the monolithic body facing the buried cavity; and

a decoupling trench extending into the monolithic body as far as the buried cavity, the decoupling trench decoupling the sensitive region from a peripheral portion of the monolithic body and forming the sensitive region.

15. The electronic device according to claim 14, wherein the electronic apparatus is at least one of a sphygmomanometer, a household apparatus, a mobile phone, a personal digital assistant, a notebook, and a pressure measuring apparatus.

16. The electronic device according to claim 14, wherein the cap is coupled to the first face of the monolithic body and integrates an application-specific integrated circuit.

17. The electronic device according to claim 14, wherein the cap is coupled to the second face of the monolithic body and integrates an application-specific integrated circuit.

18. The electronic device according to claim 17, wherein the monolithic body includes a through hole at the second face that places the buried cavity in fluid communication with an environment that is external to the micro-electro-mechanical device.