Mirror micromechanical structure and related manufacturing process

• US 9,835,850 B2
• Filed: 12/07/2015
• Issued: 12/05/2017
• Est. Priority Date: 01/14/2013
• Status: Active Grant

• Current Assignee: STMicroelectronics International N.V. (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Carminati, Roberto, Conti, Sebastiano, Constantini, Sonia
• Primary Examiner(s): Phan, James
• Application Number:
  US14/961,507
• Publication Number:
  US 20160094831A1
• Time in Patent Office: 729 Days
• Field of Search: 3592121, 3591991-1994, 3592006-2008, 3592241-2242, 359298, 3592122
• CPC Class Codes: G01B 11/2518 Projection by scanning of the object
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G02B 26/085 the reflecting means being moved or deformed by electromagnetic means
• CPC Class Codes: G02B 26/0858 the reflecting means being moved or deformed by piezoelectric means
• CPC Class Codes: G02B 26/105 with one or more pivoting mirrors or galvano-mirrors G02B26/101 takes precedence
• CPC Class Codes: G03B 21/008 using micromirror devices
• CPC Class Codes: H04N 13/211 using temporal multiplexing
• CPC Class Codes: H04N 13/236 using varifocal lenses or mirrors
• CPC Class Codes: H04N 13/254 in combination with electromagnetic radiation sources for illuminating objects
• CPC Class Codes: H04N 23/56 provided with illuminating means
• CPC Class Codes: H04N 23/57 Mechanical or electrical details of cameras or camera modules specially adapted for being embedded in other devices
• CPC Class Codes: Y10T 29/49 Method of mechanical manufacture

Abstract

A mirror micromechanical structure has a mobile mass carrying a mirror element. The mass is drivable in rotation for reflecting an incident light beam with a desired angular range. The mobile mass is suspended above a cavity obtained in a supporting body. The cavity is shaped so that the supporting body does not hinder the reflected light beam within the desired angular range. In particular, the cavity extends as far as a first side edge wall of the supporting body of the mirror micromechanical structure. The cavity is open towards, and in communication with, the outside of the mirror micromechanical structure at the first side edge wall.

Claims

1. An optical device, comprising:

a mirror micromechanical structure having;

a mobile mass which carries a mirror element and is configured to be driven in rotation for reflecting an incident light beam with a desired angular range;

said mobile mass suspended above a cavity provided in a supporting body including semiconductor material,

wherein said cavity is so shaped that said supporting body does not hinder the light beam reflected by said mirror element within said desired angular range; and

wherein said mirror element is carried by said mobile mass in a condition of rest at an angle of inclination formed between a normal to a surface of said mirror and said incident light beam of between 40° and

50°

, and a movement of rotation of said mobile mass for said angular range has an angular extension comprised between −

(15 to 25°

) and +(15 to 25°

) with respect to said condition of rest.

2. The device according to claim 1, further comprising:

an image-projection module including said mirror micromechanical structure and a source operable for generating said incident light beam; and

an image-capturing module operatively coupled to said image-projection module for capturing images associated to the light beam reflected by said mirror micromechanical structure.

3. The device according to claim 2, further comprising a processing module configured to receive and process the images captured by said image-capturing module to form three-dimensional images.

4. The device according to claim 2, wherein the image-capturing module has a field of view which at least partially overlaps the desired angular range.

5. The device according to claim 4, wherein the image projection module is configured to project within the desired angular range a pattern of parallel lines, and wherein the image-capturing module is configured to obtain corresponding two-dimensional images.

6. The device according to claim 5, further comprising a processing module configured to receive and process the two-dimensional images captured by said image-capturing module to reconstruct a three-dimensional image of an object and its surrounding environment.

7. The device according to claim 6, wherein the processing module uses a parallax principle processing algorithms to process the two-dimensional images captured by the image-capturing module in order to determine depth and distance in three-dimensional space.

8. The device according to claim 1, wherein said cavity extends as far as a first side edge wall of said supporting body, being open towards, and communicating with, an outside edge of said mirror micromechanical structure at said first side edge wall.

9. The device structure according to claim 8, wherein said mobile mass has a rotational movement about an axis of rotation, and wherein said cavity extends as far as said first side edge wall along an axis of extension, transverse to said axis of rotation.

10. The device according to claim 8, wherein said cavity has a first width, at said first side edge wall, and a second width, underneath said mobile mass, wherein said second width is smaller than said first width.

11. The device according to claim 1, wherein said mobile mass is coupled to anchorages towards said supporting body via elastic torsional elements which define an axis of rotation for said mobile mass.

12. The device according to claim 1, further comprising a structural body in which said mobile mass is defined and coupled to said supporting body.

13. The device according to claim 12, wherein said structural body and said supporting body are defined from a silicon-on-insulator wafer.

14. The device according to claim 1, wherein the supporting body has a top surface including said cavity and wherein said mobile mass has a bottom surface coplanar with the top surface of the supporting body and suspended above said cavity in a configuration which permits oscillation of the mobile mass about an axis of rotation.

15. The device according to claim 14, wherein said cavity provides a first open region on a first side of the mobile mass and a second open region on a second side of the mobile mass, said second side located opposite the first side relative to the axis of rotation, said second open region being larger than said first open region.

16. The device of claim 15, wherein said supporting body has a side edge, and wherein said second open region extends to said side edge.

17. An optical device, comprising:

an image-projection module including a mirror micromechanical structure and a source operable for generating an incident light beam, said mirror micromechanical structure having;

a mobile mass which carries a mirror element and is configured to be driven in rotation for reflecting the incident light beam with a desired angular range;

said mobile mass suspended above a cavity provided in a supporting body including semiconductor material,

wherein said cavity is so shaped that said supporting body does not hinder the light beam reflected by said mirror element within said desired angular range;

an image-capturing module operatively coupled to said image-projection module for capturing images associated to the light beam reflected by said mirror micromechanical structure; and

a processing module configured to receive and process the images captured by said image-capturing module to form three-dimensional images.

18. The device according to claim 17, wherein said cavity extends as far as a first side edge wall of said supporting body, being open towards, and communicating with, an outside edge of said mirror micromechanical structure at said first side edge wall.

19. The device according to claim 17, wherein the supporting body has a top surface including said cavity and wherein said mobile mass has a bottom surface coplanar with the top surface of the supporting body and suspended above said cavity in a configuration which permits oscillation of the mobile mass about an axis of rotation.

20. The device according to claim 19, wherein said cavity provides a first open region on a first side of the mobile mass and a second open region on a second side of the mobile mass, said second side located opposite the first side relative to the axis of rotation, said second open region being larger than said first open region.

21. The device of claim 20, wherein said supporting body has a side edge, and wherein said second open region extends to said side edge.

22. An optical device, comprising:

an image-projection module including a mirror micromechanical structure and a source operable for generating an incident light beam, said mirror micromechanical structure having;

a mobile mass which carries a mirror element and is configured to be driven in rotation for reflecting an incident light beam with a desired angular range;

said mobile mass suspended above a cavity provided in a supporting body including semiconductor material,

wherein said cavity is so shaped that said supporting body does not hinder the light beam reflected by said mirror element within said desired angular range;

an image-capturing module operatively coupled to said image-projection module for capturing images associated to the light beam reflected by said mirror micromechanical structure;

wherein the image-capturing module has a field of view which at least partially overlaps the desired angular range;

wherein the image-projection module is configured to project within the desired angular range a pattern of parallel lines, and wherein the image-capturing module is configured to obtain corresponding two-dimensional images; and

a processing module configured to receive and process the two-dimensional images captured by said image-capturing module to reconstruct a three-dimensional image of an object and its surrounding environment.

23. The device according to claim 22, wherein the processing module uses a parallax principle processing algorithms to process the two-dimensional images captured by the image-capturing module in order to determine depth and distance in three-dimensional space.

24. The device according to claim 22, wherein said cavity extends as far as a first side edge wall of said supporting body, being open towards, and communicating with, an outside edge of said mirror micromechanical structure at said first side edge wall.

25. The device according to claim 22, wherein the supporting body has a top surface including said cavity and wherein said mobile mass has a bottom surface coplanar with the top surface of the supporting body and suspended above said cavity in a configuration which permits oscillation of the mobile mass about an axis of rotation.

26. The device according to claim 25, wherein said cavity provides a first open region on a first side of the mobile mass and a second open region on a second side of the mobile mass, said second side located opposite the first side relative to the axis of rotation, said second open region being larger than said first open region.

27. The device of claim 26, wherein said supporting body has a side edge, and wherein said second open region extends to said side edge.