Micromechanical systems device comprising a displaceable electrode and a charge-trapping layer

• US 7,550,794 B2
• Filed: 09/20/2002
• Issued: 06/23/2009
• Est. Priority Date: 09/20/2002
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: IDC, LLC
• Inventors: Chui, Clarence, Miles, Mark W., Kothari, Manish, Batey, John
• Primary Examiner(s): NGUYEN, THANH T
• Application Number:
  US10/251,196
• Publication Number:
  US 20040058532A1
• Time in Patent Office: 2,468 Days
• Field of Search: 438 48- 53, 257/254
• US Class Current: 257/254
• CPC Class Codes: B81B 3/0035 Constitution or structural means for controlling the movement of the flexible or deformable elements
• 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

Abstract

In one embodiment, the invention provides a method for fabricating a microelectromechanical systems device. The method comprises fabricating a first layer comprising a film having a characteristic electromechanical response, and a characteristic optical response, wherein the characteristic optical response is desirable and the characteristic electromechanical response is undesirable; and modifying the characteristic electromechanical response of the first layer by at least reducing charge build up thereon during activation of the microelectromechanical systems device.

Claims

1. A microelectromechanical systems device comprising:

a substrate;

a first electrode located over the substrate;

a displaceable layer, wherein the displaceable layer comprises a second electrode;

an air gap, wherein said air gap is located between the first electrode and the second electrode;

a charge-trapping layer located between one of the electrodes and the air gap, wherein the charge-trapping layer comprises a material capable of trapping both positive and negative charge, and wherein the charge trapping layer is configured to increase a difference between an actuation voltage and a release voltage of the microelectromechanical systems device relative to the device without the charge trapping layer; and

a transparent layer formed between the charge-trapping layer and said one of the electrodes; and

a layer comprising Al₂O₃ located between the transparent layer and said one of the electrodes, wherein the layer comprising Al₂O₃ is located directly adjacent said one of the electrodes.

2. The device of claim 1, wherein the microelectromechanical systems device comprises an interferometric modulator, and wherein the interferometric modulator is operable to reflect light of a certain wavelength.

3. The device of claim 1, wherein the displaceable layer is movable between a first position and a second position, and wherein the device has a first optical response when the displaceable layer is in the first position, and a second optical response when the displaceable layer is in the second position.

4. The device of claim 3, wherein the device reflects a light of a certain wavelength when the displaceable layer is in the first position, and wherein the device absorbs the light when the displaceable layer is in the second position.

5. The device of claim 1, wherein the device comprises a reflective display.

6. The device of claim 1, wherein the charge-trapping layer comprises a material selected from the group of AlO_x (non-stoichiometric), Si₃N₄, SiN_x(non-stoichiometric), Ta₂O₅, and TaO_x (non-stoichiometric).

7. A microelectromechanical systems device comprising:

a fixed electrode located over a substrate;

an electrostatically displaceable layer separated from the fixed electrode by an air gap;

a layer comprising Al₂O₃ located over the fixed electrode;

a transparent layer located over the layer comprising Al₂O₃; and

a charge-trapping layer located over the transparent layer.

8. The device of claim 7, wherein the transparent layer comprises SiO₂.

9. The device of claim 7, wherein the charge-trapping layer comprises a material selected from the group of AlO_x (non-stoichiometric), Si₃N₄, SiN_x (non-stoichiometric), Ta₂O₅, and TaO_x (non-stoichiometric).

10. The device of claim 7, wherein the charge-trapping layer comprises Al₂O₃.

11. The device of claim 10, wherein the transparent layer comprises SiO₂.

12. The device of claim 7, wherein the device comprises an interferometric modulator.

13. The device of claim 7, wherein the device comprises a reflective display.