Surface micromachined optical system with reinforced mirror microstructure

• US 20030210447A1
• Filed: 05/05/2003
• Published: 11/13/2003
• Est. Priority Date: 04/23/2001
• Status: Active Grant

• Current Assignee: NeoPhotonics Corporation (Lumentum Holdings Inc.)
• Original Assignee: MEMX, Inc. (Lumentum Holdings Inc.)
• Inventors: Sniegowski, Jeffry J., Rodgers, M. Steven
• Granted Patent: US 6,778,306 B2
• Time in Patent Office: Days
• US Class Current: 359/223
• CPC Class Codes: B81B 2201/045 Optical switches
• CPC Class Codes: B81B 2203/0109 Bridges
• CPC Class Codes: B81B 2203/053 Translation according to an axis perpendicular to the substrate
• CPC Class Codes: B81B 2203/058 Rotation out of a plane parallel to the substrate
• CPC Class Codes: B81B 3/007 For controlling stiffness, e.g. ribs
• CPC Class Codes: G02B 26/00 Optical devices or arrangements for the control of light using movable or deformable optical elements control of light by modification of the optical properties of the media of the elements involved therein G02F1/00
• 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

Abstract

Various embodiments of reinforced mirror microstructures for a surface micromachined optical system are disclosed. Multi-layered and structurally reinforced mirror microstructures are disclosed, including both two and three-layer microstructures. Adjacent structural layers in these multi-layered mirror microstructures may be structurally reinforced and interconnected by a plurality of vertically disposed columns, or by a plurality of at least generally laterally extending rails or ribs, or some combination thereof. Various embodiments of a single layered mirror microstructure with a structural reinforcement assembly that cantilevers from a lower surface thereof is also disclosed.

Claims

1. A surface micromachined optical system that comprises:

a first substrate;

a first mirror microstructure disposed in spaced relation to and movably interconnected with said first substrate; and

a first actuator associated with said first mirror microstructure, wherein said first mirror microstructure comprises;

a first structural layer disposed in spaced relation to said first substrate;

a second structural layer disposed in spaced relation to said first structural layer, wherein said first structural layer is disposed between said second structural layer and said first substrate; and

a plurality of first columns that are disposed in spaced relation relative to each other, and further that extend between and fixedly interconnect said first and second structural layers, wherein each said first column is fixed to each of said first and second structural layers such that said first structural layer, said second structural layer, and said plurality of first columns collectively move together in response to said first actuator.

2. A system, as claimed in claim 1, wherein:

said first and second structural layers are at least substantially vertically aligned.

3. A system, as claimed in claim 1, wherein:

a first center of said first structural layer is vertically aligned with a second center of said second structural layer.

4. A system, as claimed in claim 1, wherein:

said first and second structural layers are first and second polysilicon layers, respectively, wherein said plurality of first columns are polysilicon, and wherein said first substrate is silicon.

5. A system, as claimed in claim 1, wherein:

said second structural layers comprises a plurality of etch release holes that extend through an entire thickness of said second structural layer.

6. A system, as claimed in claim 1, wherein:

said second structural layer comprises first and second oppositely disposed surfaces, wherein said first surface projects toward said first structural layer, and wherein said second surface comprises an optically reflective surface.

7. A system, as claimed in claim 6, wherein:

a minimum surface area of said optically reflective surface is about 2,000 μ

m².

8. A system, as claimed in claim 1, wherein:

said second structural layer comprises first and second oppositely disposed surfaces, wherein said first surface projects toward said first structural layer, and wherein said first mirror microstructure further comprises a first optically reflective layer that is deposited on said second surface.

9. A system, as claimed in claim 8, wherein:

said first optically reflective layer comprises a material selected from the group consisting of gold, silver, and aluminum.

10. A system, as claimed in claim 8, wherein:

a minimum surface area of said optically reflective surface is about 2,000 μ

m².

11. A system, as claimed in claim 1, wherein:

said plurality of first columns are disposed at least substantially perpendicular to each of said first and second structural layers.

12. A system, as claimed in claim 1, wherein:

said plurality of first columns structurally reinforce said second structural layer.

13. A system, as claimed in claim 1, wherein:

said plurality of first columns are at least substantially uniformly distributed across at least substantially an entirety of said second structural layer.

14. A system, as claimed in claim 1, wherein:

said plurality of first columns are equally spaced.

15. A system, as claimed in claim 1, wherein:

said mirror microstructure comprises a center that extends through said first and second structural layers, wherein individual members of a first pair of said plurality of first columns are disposed at a different radial distance from said center.

16. A system, as claimed in claim 1, wherein:

at least one of said first columns is positioned relative to a center of said second structural layer in a lateral dimension such that a reinforcement ratio is no more than about 0.5, wherein said reinforcement ratio is a ratio of a first distance to a second distance, wherein said first distance is a distance from said center to said at least one first column, and wherein said second distance is a diameter of said second structural layer.

17. A system, as claimed in claim 1, wherein:

a diameter of each of said plurality of first columns is less than twice a thickness of said second structural layer.

18. A system, as claimed in claim 1, wherein:

a maximum thickness of each of said first and second structural layers is about 10 μ

m.

19. A system, as claimed in claim 1, wherein:

a maximum thickness of each of said first and second structural layers is about 6 μ

m.

20. A system, as claimed in claim 1, wherein:

said surface micromachined optical system comprises means for providing a function selected from the group consisting of optical switching, optical correction, and optical scanning.