MICRO-MIRROR WITH ELECTRODE SPACER

• US 20110149361A1
• Filed: 12/16/2010
• Published: 06/23/2011
• Est. Priority Date: 12/23/2009
• Status: Active Grant

• Current Assignee: Lumentum Operations, LLC (Lumentum Holdings Inc.)
• Original Assignee: Viavi Solutions, Inc. (Lumentum Holdings Inc.)
• Inventors: Moidu, Abdul Jaleel K.
• Granted Patent: US 8,665,506 B2
• Time in Patent Office: Days
• US Class Current: 359/221.2
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G02B 26/10 Scanning systems
• CPC Class Codes: G02B 26/105 with one or more pivoting mirrors or galvano-mirrors G02B26/101 takes precedence
• CPC Class Codes: Y10T 29/49105 Switch making

Abstract

A micro-mirror includes stiffer end sections for limiting curvature, and thin middle sections forming ground electrodes and a hinge. Spacers arc provided beneath the thin middle sections of the micro-mirror for supporting hot electrodes, which attract the ground electrodes for rotating the micro-mirror about a tilt axis. The spacers enable the gap between the hot electrode and the micro-mirror to be designed separately from the thickness of the micro-mirror, and the gap between the ends of the micro-mirror and the substrate.

Claims

1. A micro-mirror device comprising:

a substrate defining a lower level;

a first spacer extending upwardly from the substrate forming an upper level;

an anchor post extending upwardly from the substrate or the spacer;

a tilting platform pivotally connected to the anchor post above the substrate via a hinge defining a tilting axis, the tilting platform including a first thin section above the upper level of the substrate, and a stiffer section at each end thereof including stiffening ribs in a lower surface thereof above the lower level of the substrate defining a swing space therebetween; and

a first hot electrode on the first spacer below the first thin section defining an electrode gap for pivoting the tilting platform about the tilting axis,

whereby tolerance variations in hinge thickness arc at least partially compensated for by a corresponding variation in electrode gap; and

whereby the swing space is independent of the electrode gap.

2. The micro-mirror device according to claim 1, wherein the substrate and the first spacer are comprised in a single wafer.

3. The micro-mirror device according to claim 1, wherein the first spacer is comprised of a different material bonded on top of the substrate.

4. The micro-mirror device according to claim 3, wherein the first spacer comprises a conductive material, wherein the first spacer includes the first hot electrode.

5. The micro-mirror device according to claim 1, further comprising a second hot electrode on the first spacer, below a second thin section in the tilting platform, on an opposite side of the titling axis than the first hot electrode.

6. The micro-mirror device according to claim 1, further comprising a second spacer extending upwardly from the substrate to the upper level;

and a second hot electrode of the second spacer below a second thin section of the tilting platform, on an opposite side of the tilting axis than the first hot electrode.

7. The micro-mirror device according to claim 1, wherein the stiffening ribs include a bulkhead extending from one side of the tilting platform to another parallel to the tilting axis.

8. The micro-mirror device according to claim 7, wherein the stiffening ribs also include a plurality of elongated ribs extending from the bulkhead to the outer free end of the titling platform perpendicular to the tilting axis.

9. The micro-mirror device according to claim 8, wherein the tilting platform includes a mounting cap for bonding on top of the anchor post;

and wherein the mounting cap, the bulkhead and the elongated ribs are formed in a single structure and have the same thickness.

10. The micro-mirror device according to claim 1, wherein the stiffening ribs include a plurality of elongated ribs extending to the outer free end of the titling platform perpendicular to the tilting axis.

11. The micro-mirror device according to claim 1, wherein the first spacer extends upwardly from the substrate to provide improved aerodynamic cross-talk by increased effective thickness of air film underneath the tilting platform.

12. The micro-mirror device according to claim 1, further comprising a reflective, surface on the tilting platform only above one or both of the stiffer sections.

13. A method of manufacturing a micro-mirror device comprising:

a) providing a substrate defining a lower level;

b) providing a first spacer on the substrate defining an upper level;

c) providing an anchor post extending from the first spacer or the substrate;

d) providing a first hot tilt electrodes on the first spacer;

e) providing a tilting mirror platform with a thinner middle section including a hinge and a ground electrode, and stiffer end sections with a reflective coating on at least one of the end sections; and

f) mounting the tilting mirror platform with ground electrode over the hot tilt electrode, and the stiffer end sections over the lower level.

14. The method according to claim 13, wherein step b) includes etching a substrate wafer to form the spacer at the upper level extending from the substrate at the lower level with a step therebetween.

15. The method according to claim 13, wherein step b) includes providing a separate spacer, and bonding the spacer on the substrate.

16. The method according to claim 13, wherein step b) further includes providing a second spacer on the substrate extending to the upper level;

and wherein step d) further includes providing a second hot tilt electrode on the second spacer.

17. The method according to claim 13, wherein step e) includes:

i) performing a first etch to define strengthening ribs or bulkheads in the stiffer end sections; and

ii) performing a second etch to define the hinge and a mounting cap for mounting on the anchor post.

18. The method according to claim 17, wherein the first etch comprises a backside etch;

and

wherein the second etch comprises a topside etch.