Method of fabricating interferometric devices using lift-off processing techniques

• US 20060067644A1
• Filed: 06/17/2005
• Published: 03/30/2006
• Est. Priority Date: 09/27/2004
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Chui, Clarence, Tung, Ming-Hau
• Granted Patent: US 7,553,684 B2
• Time in Patent Office: Days
• US Class Current: 385/147
• 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

Embodiments of the present disclosure include a method of fabricating interferometric devices using lift-off processing techniques. Use of lift-off processing in the fabrication of various layers of interferometric modulators, such as an optical stack or a flex layer, advantageously avoids individualized chemistries associated with the plurality of materials associated with each layer thereof. Moreover, use of lift-off processing allows much greater selection in both materials and facilities available for fabrication of interferometric modulators.

Claims

1. A method of fabricating an interferometric modulator, comprising:

forming an optical stack on a transparent substrate using at least a first patterning fabrication process;

forming a supporting structure over the substrate; and

forming an upper mirror layer over the optical stack and supporting structure using at least a second pattering fabrication process;

wherein a cavity is formed by at least one surface of the optical stack, the supporting structure and the upper mirror layer, where movement of a portion of the upper mirror layer into the cavity changes the optical properties perceived from a surface of the substrate in a controllable and predictable manner, and wherein at least one of the first and second fabrication processes comprises a lift-off process.

2. The method of claim 1, wherein the optical stack comprises at least one of a conductor layer, a lower mirror metal layer, and a dielectric layer.

3. The method of claim 2, wherein the optical stack comprises a lower mirror metal layer.

4. The method of claim 3, wherein at least the lower mirror metal layer forms a row electrode.

5. The method of claim 1, wherein forming the upper mirror layer on the optical stack comprises depositing a sacrificial layer between the optical stack and the upper mirror layer.

6. The method of claim 5, further comprising removing at least a portion of the sacrificial layer to form the cavity.

7. The method of claim 5 in which the lift-off process comprises lifting off at least a portion of the optical stack along with at least a portion of the sacrificial layer.

8. The method of claim 1, wherein the upper mirror layer comprises a flexible metal conductor layer.

9. The method of claim 8, wherein at least the upper mirror layer forms a column electrode.

10. The method of claim 1, wherein the first and second fabrication processes comprise lift-off processes.

11. The method of claim 1, further comprising forming an imaging application.

12. The method of claim 11, wherein the imaging application comprises a flat panel display.

13. The method of claim 12, wherein the flat panel display is part of a mobile electronic device.

14. The method of claim 11, wherein the imaging application comprises at least one of a handheld computer, a personal digital assistant, a laptop computer, a mobile telephone, a handheld video gaming device, a home appliance, a television, a timepiece, a kiosk, and a automobile computing device.

15. The method of claim 1 in which the lift-off process comprises forming a generally T-shaped lift-off stencil.

16. The method of claim 1 in which the lift-off process comprises patterning a lift-off stencil.

17. The method of claim 16 in which the patterning of the lift-off stencil comprises depositing a photoresist over a polymer.

18. The method of claim 1 in which the lift-off process comprises wet etching to remove a lift-off stencil.

19. The method of claim 1 further comprising depositing a deformable layer over the upper mirror layer.

20. The method of claim 19 in which the upper mirror layer is suspended from the deformable layer after removal of a sacrificial layer.

32. A display panel comprising an array of interferometric modulators made by the method of claim 1.

33. A display device comprising:

the display panel of claim 32;

a processor that is in electrical communication with the display panel, the processor being configured to process image data; and

a memory device in electrical communication with the processor.

34. The display device of claim 33 further comprising:

a first controller configured to send at least one signal to the display panel; and

a second controller configured to send at least a portion of the image data to the first controller.

35. The display device of claim 33 further comprising:

an image source module configured to send the image data to the processor.

36. The display device of claim 35 wherein the image source module comprises at least one of a receiver, a transceiver, and a transmitter.

37. The display device of claim 33 further comprising:

an input device configured to receive input data and to communicate the input data to the processor.

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

forming a lift-off stencil over a substrate;

depositing a first material layer over the lift-off stencil and over the substrate;

depositing a second material layer over the first material layer; and

removing the lift-off stencil to thereby form a patterned region comprising the second material layer over the first material layer.

22. The method of claim 21 in which the first material layer comprises indium tin oxide.

23. The method of claim 22 in which the second material layer comprises at least one metal selected from the group consisting of chromium, molybdenum and titanium.

24. The method of claim 23 in which the second material layer comprises molybdenum.

25. The method of claim 23 in which the first material layer has a thickness that is greater than a thickness of the second material layer.

26. The method of claim 21 further comprising depositing a third material layer over the second material layer.

27. The method of claim 26 in which the third material layer comprises a dielectric material.

28. The method of claim 26 further comprising depositing a fourth material layer over the third material layer.

29. The method of claim 28 in which the fourth material layer comprises molybdenum.

30. A method of fabricating an array of interferometric modulators, comprising:

forming a plurality of positively patterned optical stacks and a plurality of negatively patterned post regions on a substrate using a lift-off stencil; and

forming a plurality of post structures in the negatively patterned post regions.

31. A method of making a display device, comprising:

depositing a first mirror layer;

depositing a sacrificial layer over the first mirror layer;

forming a lift-off stencil over the sacrificial layer;

depositing a second mirror layer over the lift-off stencil;

removing the lift-off stencil, thereby forming a patterned region of the second mirror layer and exposing a portion of the sacrificial layer.