Micro-electro-mechanical device and manufacturing process thereof

Patent metadata

Field	Value
Publication number	US-10626008-B2
Application number	US-201816207035-A
Country	US
Kind code	B2
Filing date	Nov 30, 2018
Priority date	Nov 19, 2015
Publication date	Apr 21, 2020
Grant date	Apr 21, 2020

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.

First claim

The invention claimed is:

1. A method, comprising:
forming a first buried cavity in a monolithic body of semiconductor material; and
forming a sensitive region in the monolithic body facing the first buried cavity, wherein forming the sensitive region includes forming a single trench that extends into the monolithic body as far as the first buried cavity, the single trench extending around the sensitive regions so that a first end of the single trench overlaps a second end of the single trench.

2. The method of claim 1 , further comprising forming a second buried cavity in the sensitive region, the second buried cavity overlapping the first buried cavity.

3. The method of claim 1 , further comprising coupling a perimeter of a membrane to the sensitive region, the membrane being arranged over the sensitive region.

4. The method of claim 3 , wherein the membrane is spaced apart from the sensitive region by a cavity.

5. The method of claim 1 , further comprising coupling a cap element to a surface of the peripheral portion of the monolithic body.

6. The method of claim 1 , wherein the single trench has a spiral shape that extends around an entire perimeter of the sensitive region.

7. The method of claim 6 , wherein the single 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.

8. A method, comprising:
forming a buried cavity in a monolithic body of semiconductor material;
forming a sensitive region in the monolithic body of semiconductor material covering the buried cavity; and
forming 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 method of claim 8 , wherein forming the sensitive region includes forming a decoupling trench that separates the sensitive region from a peripheral portion of the monolithic body.

10. The method of claim 9 , wherein the decoupling trench has a spiral shape.

11. The method of claim 10 , wherein the spiral shape extends around an entire perimeter of the sensitive region.

12. The method of claim 8 , further comprising coupling a cap to the perimeter portion of the monolithic body, the cap forming a cavity with the monolithic body, the movable element being located in the cavity.

13. The method of claim 8 , further comprising forming a through opening in the monolithic body, the through opening placing the buried cavity in fluid communication with an environment that is external to the monolithic body.

14. A method, comprising:
forming a first buried cavity in a monolithic body of semiconductor material; and
decoupling a sensitive region in the monolithic body from a peripheral portion of the monolithic body by forming a single spiral shaped trench that extends around an entire perimeter of the sensitive region, the sensitive region facing the first buried cavity.

15. The method of claim 14 , further comprising forming a second buried cavity in the sensitive region.

16. The method of claim 15 , wherein the second buried cavity overlaps the first buried cavity.

17. The method of claim 14 , further comprising coupling a membrane to the sensitive region.

18. The method of claim 17 , wherein the membrane is arranged over the sensitive region and is spaced apart from the sensitive region.

19. The method of claim 18 , further comprising coupling a cap to a surface of the peripheral portion.

20. The method of claim 14 , wherein the single spiral shaped trench is a square spiral shape.

Assignees

• St Microelectronics Srl

Inventors

• Baldo Lorenzo
• Duqi Enri
• Villa Flavio Francesco

Classifications

• B81B2201/025

  Inertial sensors not provided for in B81B2201/0235 - B81B2201/0242 · CPC title

• B81B7/02 Primary

  containing distinct electrical or optical devices of particular relevance for their function, e.g. microelectro-mechanical systems [MEMS] (B81B7/04 takes precedence) · CPC title

• B81B2203/0315

  Cavities · CPC title

• B81B2201/0228

  Inertial sensors · CPC title

• B81C1/00325

  for reducing stress inside of the package structure · CPC title