MEMS OPTICAL SWITCH ACTUATOR

• US 20030210851A1
• Filed: 12/01/2000
• Published: 11/13/2003
• Est. Priority Date: 12/01/2000
• Status: Active Grant

• Current Assignee: Corning Incorporated
• Original Assignee: Corning Incorporated
• Inventors: Merchant, Paul P., Lambert, David W., Fu, Xiaodong R.
• Granted Patent: US 6,647,171 B1
• Time in Patent Office: Days
• US Class Current: 385/18
• CPC Class Codes: G02B 6/3514 the reflective optical element moving along a line so as to translate into and out of the beam path, i.e. across the beam path
• CPC Class Codes: G02B 6/3518 the reflective optical element being an intrinsic part of a MEMS device, i.e. fabricated together with the MEMS device MEMS devices in general B81B; manufacture of MEM devices in general B81C; micromechanical devices controlling the direction of light G02B26/0833
• CPC Class Codes: G02B 6/3546 NxM switch, i.e. a regular array of switches elements of matrix type constellation
• CPC Class Codes: G02B 6/357 Electrostatic force electrostatic forces controlling reflecting elements in general G02B26/0841
• CPC Class Codes: G02B 6/358 Latching of the moving element, i.e. maintaining or holding the moving element in place once operation has been performed; includes a mechanically bistable system
• CPC Class Codes: G02B 6/3584 constructional details of an associated actuator having a MEMS construction, i.e. constructed using semiconductor technology such as etching MEMS per se B81B, B81C
• CPC Class Codes: G02B 6/3596 With planar waveguide arrangement, i.e. in a substrate, regardless if actuating mechanism is outside the substrate

Abstract

A micro-electro-mechanical system (MEMS) optical switch actuator and method for fabricating the actuator provide an anchor assembly that functions as a second electrode. The actuator has a reflective element assembly and a first electrode assembly for moving the reflective element assembly from a first position to a second position based on a switching signal. The actuator further includes an anchor assembly coupled to the reflective element assembly such that a spring force is generated in the reflective element assembly when the reflective element assembly is in the second position. The anchor assembly is electrically conductive such that the switching signal generates an electrostatic force between the anchor assembly and the first electrode assembly. The method for fabricating the actuator includes the step of coupling a multi-level reflection assembly to an optical circuit. The reflection assembly has an electrically conductive anchor assembly positioned at a first level with respect to the optical circuit and a mirror positioned at a second level with respect to the optical circuit. An insulative mirror beam layer is then coupled to the reflection assembly, and an electrode assembly is coupled to the mirror beam layer. The electrode assembly is coupled such that a voltage potential between the anchor assembly and the electrode assembly causes the electrode assembly to force the mirror beam layer and the mirror from the first switching position to the second switching position.

Claims

1. A micro-electro-mechanical-system (MEMS) optical switch actuator comprising:

a reflective element assembly;

a first electrode assembly for moving the reflective element assembly from a first position to a second position based on a switching signal; and

an anchor assembly coupled to the reflective element assembly such that a spring force is generated in the reflective element assembly when the reflective element assembly is in the second position, the anchor assembly being electrically conductive such that the switching signal generates an electrostatic force between the anchor assembly and the first electrode assembly.

2. The actuator of claim 1 wherein the first electrode assembly includes:

an actuator beam;

a contact stud coupled to the actuator beam; and

a pillar structure for supporting the actuator beam adjacent to the reflective element assembly such that the contact stud moves the reflective element assembly from the first position to the second position in response to the switching signal.

3. The actuator of claim 2 wherein the pillar structure includes a single pillar architecture for supporting the actuator beam at a first end such that a second end of the actuator beam is free standing.

4. The actuator of claim 2 wherein the pillar structure includes a dual pillar architecture for supporting the actuator beam at a first end and a second end.

5. The actuator of claim 1 wherein the anchor assembly includes:

a first anchor for supporting the reflective element assembly at a first end; and

a second anchor for supporting the reflective element assembly at a second end.

6. The actuator of claim 5 wherein each anchor includes:

an electrode; and

an extension coupled to the electrode and the reflective element assembly.

7. The actuator of claim 1 wherein the reflective element assembly includes:

a non-electrically conductive mirror beam; and

a mirror coupled to the mirror beam.

8. A method for fabricating a micro-electro-mechanical-system (MEMS) optical switch actuator, the method comprising the steps of:

coupling a multi-level reflection assembly to an optical circuit, the reflection assembly having an electrically conductive anchor assembly positioned at a first level with respect to the optical circuit and a mirror positioned at a second level with respect to the optical circuit;

coupling an insulative mirror beam layer to the reflection assembly; and

coupling an electrode assembly to the mirror beam layer such that a voltage potential between the anchor assembly and the electrode assembly causes the electrode assembly to force the mirror beam layer and the mirror from a first switching position to a second switching position.

9. The method of claim 8 further including the steps of:

generating actuation anchor regions in a waveguide layer of the optical circuit, the actuation anchor regions being defined by walls that extend from a top surface of the waveguide layer to a top surface of a substrate of the optical circuit;

generating a mirror region within a recess of the waveguide layer, the mirror region being defined by walls that extend from the top surface of the waveguide layer to an intermediate level within the waveguide layer;

disposing the anchor assembly within the actuation anchor regions; and

disposing the mirror within the mirror region.

10. The method of claim 9 further including the steps of:

depositing a plastic polymer layer on the top surface of the waveguide layer and within the recess of the waveguide layer;

depositing a photoresist layer on the plastic polymer layer;

patterning the photoresist layer to open the mirror region and the actuation anchor regions from the top surface of the waveguide layer to the intermediate level; and

etching the actuation anchor regions to the top surface of the substrate.

11. The method of claim 10 further including the step of using polyimide as the plastic polymer.

12. The method of claim 10 further including the steps of:

depositing a metallic layer on the top surface of the waveguide layer and within the mirror region; and

stripping the metallic layer in an acid dip such that the actuation anchor regions are etched to the top surface of the substrate.

13. The method of claim 12 further including the step of using titanium as the metallic layer.

14. The method of claim 9 further including the steps of:

depositing an adhesive layer on the top surface of the waveguide layer, within the mirror region, and within the actuation anchor regions;

etching the adhesive layer from the mirror region and a portion of the top surface of the waveguide layer such that the adhesive layer remains in the actuation anchor regions and in reflective anchor regions, the reflective anchor regions defined by the portion of the top surface of the waveguide layer having the adhesive layer;

depositing an optically reflective layer on the top surface of the waveguide layer, within the actuation anchor regions, within the mirror region, and within the reflective anchor regions;

etching the optically reflective layer from the top surface of the waveguide layer; and

depositing a metallic layer on the remaining optically reflective layer.

15. The method of claim 14 further including the step of using gold for the optically reflective layer.

16. The method of claim 14 further including the step of using nickel for the metallic layer.

17. The method of claim 8 further including the steps of:

depositing the insulative mirror beam layer on the reflection assembly under tensile stress; and

etching the mirror beam layer from a portion of a top surface of a waveguide layer of the optical circuit such that a bridge is formed;

said bridge suspending the mirror of the multi-level reflection assembly at the first level.

18. The method of claim 17 further including the step of using SiN for the insulative mirror beam layer.

19. The method of claim 8 further including the steps of:

depositing a plastic polymer layer on a top surface of a waveguide layer of the optical circuit and on the mirror beam layer;

curing the plastic polymer layer;

depositing a metallic layer on the plastic polymer layer;

masking the metallic layer in a desired post configuration;

etching the metallic layer and the plastic polymer layer such that electrode regions are generated, the electrode regions being defined by walls extending from a top surface of the plastic polymer layer to a top surface of the mirror beam layer;

depositing a seed layer on the top surface of the plastic polymer layer and within the electrode regions;

depositing an electrode layer on the seed layer;

masking the electrode layer in a desired bridge configuration;

etching the electrode layer such that the electrode assembly is generated; and

removing the plastic polymer layer.

20. The method of claim 19 further including the step of using polyimide for the plastic polymer layer.

21. The method of claim 19 further including the step of using titanium for the metallic layer.

22. The method of claim 19 further including the step of reactive ion etching the metallic layer.

23. The method of claim 19 further including the step of using Cr/Ni for the seed layer.

24. The method of claim 19 further including the step of using nickel for the electrode layer.