Method and device for protecting interferometric modulators from electrostatic discharge

• US 20060077504A1
• Filed: 05/02/2005
• Published: 04/13/2006
• Est. Priority Date: 09/27/2004
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: IDC, LLC
• Inventors: Floyd, Philip D.
• Granted Patent: US 7,405,861 B2
• Time in Patent Office: Days
• US Class Current: 359/237
• CPC Class Codes: B81B 2201/047 Optical MEMS not provided for in B81B2201/042 - B81B2201/045
• CPC Class Codes: B81B 7/0012 Protection against reverse engineering, unauthorised use, use in unintended manner, wrong insertion or pin assignment
• CPC Class Codes: G02B 26/001 based on interference in an adjustable optical cavity interference filters G02B5/28; devices or arrangements using multiple reflections in spectrometry or monochromators G01J3/26
• CPC Class Codes: H01L 27/0248 for electrical or thermal protection, e.g. electrostatic discharge [ESD] protection

Abstract

A MEMS device such as an interferometric modulator includes an integrated ESD protection element capable of shunting to ground an excess current carried by an electrical conductor in the MEMS device. The protection element may be a diode and may be formed by depositing a plurality of doped semiconductor layers over the substrate on which the MEMS device is formed.

Claims

1. A MEMS device comprising:

a moveable element;

an electrical conductor configured to carry an actuation current that is effective to actuate the moveable element; and

a protection element operably attached to the electrical conductor and configured to at least partially shunt to ground an excess current carried by the electrical conductor,

the moveable element, electrical conductor and protection element being integrated over a substrate.

2. The MEMS device of claim 1 in which the protection element comprises a diode.

3. The MEMS device of claim 2 in which the diode is selected from the group consisting of back-to-back Zener diode, standard Zener diode, low capacitance Zener diode, symmetrical Zener diode, and low capacitance symmetrical diode.

4. The MEMS device of claim 2 in which the diode comprises a plurality of doped semiconductor layers.

5. The MEMS device of claim 1 in which the moveable element, electrical conductor and protection element are at a substantially same level over the substrate.

6. An interferometric modulator comprising:

an electrode integrated with a substrate and configured to carry an actuation current; and

a protection element connected to the electrode and configured to at least partially shunt to ground an excess current carried by the electrode, the protection element being integrated with the substrate.

7. The interferometric modulator of claim 6 in which the protection element comprises a diode.

8. The interferometric modulator of claim 7 in which the diode is selected from the group consisting of back-to-back Zener diode, standard Zener diode, low capacitance Zener diode, symmetrical Zener diode, and low capacitance symmetrical diode.

9. The interferometric modulator of claim 7 in which the diode comprises a plurality of doped semiconductor layers.

10. The interferometric modulator of claim 6 in which the electrode and the protection element are at a substantially same level over the substrate.

11. The interferometric modulator of claim 6 further comprising a mirror operably attached to the electrode.

12. The interferometric modulator of claim 11 further comprising a second mirror spaced apart from and substantially parallel to the first mirror.

13. The interferometric modulator of claim 12 further comprising a second electrode operably attached to the second mirror.

14. The interferometric modulator of claim 13 further comprising a second protection element operably attached to the second electrode and configured to at least partially shunt to ground a second excess current carried by the second electrode.

15. The interferometric modulator of claim 14 in which the second protection element comprises a diode.

16. The interferometric modulator of claim 15 in which the diode is selected from the group consisting of back-to-back Zener diode, standard Zener diode, low capacitance Zener diode, symmetrical Zener diode, and low capacitance symmetrical diode.

17. A display device comprising;

a substrate;

a plurality of interferometric modulators formed over the substrate; and

a plurality of protection elements integrated with the plurality of interferometric modulators over the substrate;

the plurality of protection elements being electrically connected to at least partially protect the plurality of interferometric modulators from an electrostatic discharge.

18. The display device of claim 17 in which the plurality of protection elements comprises a plurality of doped semiconductor layers.

19. The display device of claim 17 further comprising in which the plurality of interferometric modulators are connected by row and column lines.

20. The display device of claim 19 in which the row and columns lines are attached to the plurality of protection elements.

21. A method of making an interferometric modulator device comprising:

depositing a first electrode layer over a substrate;

depositing a sacrificial layer over the first electrode layer;

depositing a second electrode layer over the sacrificial layer;

depositing a plurality of doped semiconductor layers over the substrate; and

forming a ground plane over the substrate, the ground plane and the plurality of doped semiconductor layers being configured to shunt to ground an excess current carried by at least one of the first electrode layer and the second electrode layer.

22. The method of claim 21 further comprising removing the sacrificial layer.

23. The method of claim 21 further comprising depositing the ground plane over the plurality of doped semiconductor layers.

24. The method of claim 21 further comprising depositing the plurality of doped semiconductor layers over the ground plane.

25. The method of claim 21 further comprising depositing the ground plane near a periphery of the substrate.