Microelectromechanical devices including rotating plates and related methods

• US 6,256,134 B1
• Filed: 07/28/2000
• Issued: 07/03/2001
• Est. Priority Date: 09/27/1996
• Status: Expired due to Term

• Current Assignee: MCNC, Inc.
• Original Assignee: MCNC, Inc.
• Inventors: Koester, David A., Markus, Karen W., Walters, Mark D., Dhuler, Vijayakumar R.
• Primary Examiner(s): Phan, James
• Application Number:
  US09/628,054
• Time in Patent Office: 340 Days
• Field of Search: 359/198-199, 359/212-214, 359/223, 359/224, 359/221, 359/226, 359/230
• US Class Current: 359/212.1
• CPC Class Codes: B81B 2201/042 Micromirrors, not used as optical switches
• CPC Class Codes: B81B 2203/058 Rotation out of a plane parallel to the substrate
• CPC Class Codes: B81B 3/0051 For defining the movement, i.e. structures that guide or limit the movement of an element mechanical arrangements for preventing or damping vibration or shock H01H3/60
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G02B 26/101 with both horizontal and vertical deflecting means, e.g. raster or XY scanners colour television using laser beams scanning a display screen H04N9/3129
• CPC Class Codes: Y10S 359/90 Methods
• CPC Class Codes: Y10T 428/24273 including aperture
• CPC Class Codes: Y10T 428/24322 Composite web or sheet
• CPC Class Codes: Y10T 428/24355 Continuous and nonuniform or irregular surface on layer or component [e.g., roofing, etc.]
• CPC Class Codes: Y10T 428/24479 including variation in thickness

Abstract

An electromechanical device includes a first frame having a first aperture therein, a second frame suspended in the first frame wherein the second frame has a second aperture therein, and a plate suspended in the second aperture. A first pair of beams support the second frame along a first axis relative to the first frame so that the second frame rotates about the first axis. A second pair of beams supports the plate along a second axis relative to the second frame so that the plate rotates about the second axis relative to the frame. The first and second axes preferably intersect at a 90° angle. A first actuator provides mechanical force for rotating the second frame relative to the first frame about the first axis. A second actuator provides mechanical force for rotating the plate relative to the second frame about the second axis. Accordingly, the plate can be independently rotated relative to the first axis and the second axis. Related methods are also disclosed.

Claims

1. An electromechanical device comprising:

a frame having an aperture therein;

a plate suspended in said aperture having a reflective surface for reflecting a signal directed to said plate; and

a support structure connected between said frame and plate for supporting said plate along an axis relative to said frame, wherein said support structure has at least one rotational contact that allows said plate to rotate about the axis relative to said frame.

2. An electromechanical device according to claim 1 further comprising a laser, wherein said laser generates a signal beam and directs said beam toward said reflective surface so that a reflected beam can be scanned by rotating said plate.

3. An electromechanical device according to claim 1, wherein said plate comprises a semiconductive crystal material, and wherein the reflective surface of said plate comprises a polished surface of said plate.

4. An electromechanical device according to claim 1, wherein said plate comprises a semiconductive crystal material, and wherein the reflective surface of said plate comprises a reflective material deposited on a surface of said plate.

5. An electromechanical device according to claim 1, wherein said plate comprises a semiconductive crystal material, and wherein the reflective surface of said plate comprises a layer of metallic material deposited on a surface of said plate.

6. A method for fabricating an electromechanical device having a reflective rotational surface, wherein said method comprises the steps of:

defining a plate region on a face of a substrate;

defining a frame region on the face of the substrate, wherein the frame region surrounds the plate region and wherein the plate region and the frame region are separated by a sacrificial substrate region;

forming a structure which supports the plate region along an axis relative to the frame region, wherein the support structure has at least one rotational contact that allows the plate region to rotate about the axis relative to frame region;

creating a reflective surface on a surface of the plate region; and

removing the sacrificial substrate region so that the plate region may rotate about the axis relative to the frame region responsive to mechanical forces.

7. A method according to claim 6, wherein said creating a reflective surface step comprises the step of polishing a surface of the plate region.

8. A method according to claim 6, wherein said creating a reflective surface step comprises the step of depositing a layer of reflective material on a surface of the plate region.

9. A method according to claim 6, wherein said creating a reflective surface step comprises the step of depositing a layer of metallic material on a surface of the plate region.

10. A method according to claim 6, wherein said steps of defining the plate region and defining the frame region each comprise doping the respective regions, and wherein said step of removing the sacrificial substrate region comprises etching undoped portions of the substrate.

11. A method according to claim 6, wherein said step of forming a structure which supports the plate region comprises the step of forming a pair of beams on opposite sides of the plate region which define an axis of rotation through the plate region, wherein each of the beams extends from the plate region to the frame region, and wherein a first end of each of the beams is fixedly connected to one of the plate region and the frame region and a second end of at least one of said beams is in rotational contact with the other of the plate region and the frame region so that the plate rotates relative to the frame.

12. A method according to claim 11, wherein said step of forming the first and second beams is preceded by the step of forming first and second partial holes in the sacrificial layer opposite the frame region without exposing the frame region, wherein the partial holes are formed along the axis, and wherein each of the first and second beams extends from a respective exposed portion of the plate region to a respective partial hole opposite the frame region.

13. A method according to claim 12, wherein each of the partial holes has an arched surface so that each of the beams extending into the respective partial hole forms an arched contact surface.

14. A method according to claim 6 further comprising the step of forming an actuator on a face of the substrate, wherein the actuator provides mechanical force to rotate the plate region.

15. A method according to claim 14, wherein said step of forming the actuator comprises forming an electrode spaced apart from the frame region and an arm extending from the electrode to a portion of the plate region off the axis, and wherein a potential difference between the electrode and the frame region results in an electrostatic force which is transmitted via the arm to the plate region thus rotating the plate region relative to the frame region.