Micro-mechanical actuator including auxiliary lever to enlarge travel range of actuated object

• US 6,495,893 B2
• Filed: 04/27/2001
• Issued: 12/17/2002
• Est. Priority Date: 01/02/2001
• Status: Expired due to Fees

• Current Assignee: TOUCH MICRO-SYSTEM TECHNOLOGY CORP. (Walsin Lihwa Corporation)
• Original Assignee: Hung-Yi Lin, Weileun Fang
• Inventors: Lin, Hung-Yi, Fang, Weileun
• Primary Examiner(s): Flynn, Nathan J.
• Assistant Examiner(s): Forde, Remmon R.
• Application Number:
  US09/843,913
• Publication Number:
  US 20020084499A1
• Time in Patent Office: 599 Days
• Field of Search: 257/415, 257/420, 257/421, 257/467, 438/52, 310/309, 310/323.02, 310/323.16, 200/181, 333/105, 333/262, 359/295, 359/290
• US Class Current: 257/415
• CPC Class Codes: B81B 2201/045 Optical switches
• CPC Class Codes: B81B 2203/0118 Cantilevers
• CPC Class Codes: B81B 2203/053 Translation according to an axis perpendicular to the substrate
• CPC Class Codes: B81B 3/0037 For increasing stroke, i.e. achieve large displacement of actuated parts

Abstract

A micro-mechanical actuator is disclosed for actuating an object in a micro-electro-mechanical system. One end of the object is flexibly connected a substrate, and another end is flexibly connected to an auxiliary lever which is further connected to an actuating force generator. The auxiliary lever receives an actuating force generated from the actuating force generator to perform a levering operation about a fulcrum. The position of the fulcrum allows an portion of the auxiliary lever connected to the object has a shift larger than a shift of another portion of the auxiliary lever connected to the actuating force generator in response to the actuating force.

Claims

1. A micro-mechanical actuator for actuating an object in a micro-electro-mechanical system, comprising:

a substrate for being flexibly connected thereto said object;

a first actuating force generator positioned on said substrate for generating a first actuating force;

a first auxiliary lever having opposite first and second portions thereof flexibly connected to said first actuating force generator and a first end of said object, respectively, for performing a first levering operation to transmit said object in response to said first actuating force; and

a first fulcrum element connected to said first auxiliary lever for allowing said first auxiliary lever to perform said first levering operation thereabout, and arranged at a first specific position for allowing said second portion of said first auxiliary lever has a first shift larger than a second shift of said first portion of said first auxiliary lever in response to said first actuating force.

2. The micro-mechanical actuator according to claim 1 wherein said first actuating force generator includes:

a bottom electrode secured on said substrate; and

a top electrode flexibly connected to said first auxiliary lever and said substrate, and moved downwards by an attracting electrostatic force between said top and bottom electrodes to generate said first actuating force for said first auxiliary lever.

3. The micro-mechanical actuator according to claim 1 wherein said first auxiliary lever includes a bump structure for strengthening said first auxiliary lever.

4. The micro-mechanical actuator according to claim 1 wherein said first fulcrum is secured onto said substrate via an anchor.

5. The micro-mechanical actuator according to claim 1 wherein said first specific position of said first fulcrum lies between said first and second portions of said first auxiliary lever.

6. The micro-mechanical actuator according to claim 1 wherein said specific position of said first fulcrum lies at the same side of said first and second portions.

7. The micro-mechanical actuator according to claim 1 wherein said substrate is directly connected thereto a second end of said object.

8. The micro-mechanical actuator according to claim 1 further comprising:

a second actuating force generator positioned on said substrate for generating a second actuating force;

a second auxiliary lever having opposite third and fourth portions thereof flexibly connected to said second actuating force generator and a second end of said object, respectively, for performing a second levering operation to transmit said object in response to said second actuating force; and

a second fulcrum element connected to said second auxiliary lever for allowing said second auxiliary lever to perform said second levering operation thereabout, and arranged at a second specific position for allowing said fourth portion of said second auxiliary lever has a third shift larger than a fourth shift of said third portion of said second auxiliary lever in response to said second actuating force.

9. The micro-mechanical actuator according to claim 1 wherein said substrate includes a trench positioned right under said first actuating lever and said object for providing a space at least sufficient for said first and second shifts of said first actuating lever.

10. The micro-mechanical actuator according to claim 1 wherein said substrate is a silicon substrate.

11. The micro-mechanical actuator according to claim 1 for actuating an optical switch in a micro-electro-mechanical system.

12. The micro-mechanical actuator according to claim 1 for actuating a radio-frequency (RF) switch in a micro-electro-mechanical system.

13. The micro-mechanical actuator according to claim 1 wherein said first auxiliary lever and said first fulcrum are formed by steps of:

forming a trench and a mask on said substrate;

forming a sacrificial layer over said trench;

forming a structure layer on said sacrificial layer and said mask; and

defining a pattern on said structure layer, and removing said sacrificial layer.

14. The micro-mechanical actuator according to claim 13 wherein said substrate is a silicon substrate.

15. The micro-mechanical actuator according to claim 13 wherein said mask is formed of silicon nitride.

16. The micro-mechanical actuator according to claim 15 wherein said sacrificial layer is formed of silicon dioxide.

17. The micro-mechanical actuator according to claim 15 wherein said structure layer is formed of a material selected from a group consisting of silicon nitride, polysilicon and metal.

18. The micro-mechanical actuator according to claim 13 wherein said first auxiliary lever includes a U-shaped cross section extending toward said trench.

19. The micro-mechanical actuator according to claim 13 wherein said trench is further enlarged by etching said substrate.

20. The micro-mechanical actuator according to claim 19 wherein the etching of said substrate is performed by anisotropic wet etching after removing said sacrificial layer.

21. The micro-mechanical actuator according to claim 19 wherein the etching of said substrate is performed by deep reactive ion etching from a side of said substrate opposite to said sacrificial layer before removing said sacrificial layer.

22. The micro-mechanical actuator according to claim 13 wherein said pattern further includes an anchor on said mask for securing said first fulcrum onto said substrate.