METHOD OF FABRICATING INTERFEROMETRIC DEVICES USING LIFT-OFF PROCESSING TECHNIQUES

• US 20090262412A1
• Filed: 06/29/2009
• Published: 10/22/2009
• Est. Priority Date: 09/27/2004
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: IDC, LLC
• Inventors: Chui, Clarence, Tung, Ming-Hau
• Granted Patent: US 7,906,353 B2
• Time in Patent Office: Days
• US Class Current: 359/290
• 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 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.

2. The method of claim 1 in which the first material layer comprises indium tin oxide.

3. The method of claim 2 in which the second material layer comprises at least one metal selected from the group consisting of chromium, molybdenum and titanium.

4. The method of claim 3 in which the second material layer comprises molybdenum.

5. The method of claim 3 in which the first material layer has a thickness that is greater than a thickness of the second material layer.

6. The method of claim 1 further comprising depositing a third material layer over the second material layer.

7. The method of claim 6 in which the third material layer comprises a dielectric material.

8. The method of claim 6 further comprising depositing a fourth material layer over the third material layer.

9. The method of claim 8 in which the fourth material layer comprises molybdenum.

10. 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.

11. 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.

12. The method of claim 11 in which depositing the first mirror layer comprises depositing at least one metal selected from chromium, molybdenum, titanium, and tungsten.

13. The method of claim 11 in which depositing the first mirror layer comprises selecting a thickness of the first mirror layer to thereby render the first mirror layer partially transmissive.

14. The method of claim 11 in which depositing the first mirror layer comprises controlling a deposition condition to thereby produce the first mirror layer having a thickness in the range of about 30 Å

to about 150 Å

.

15. The method of claim 11, further comprising depositing a conductor layer of an optical stack layer.

16. The method of claim 11, further comprising depositing a dielectric layer of an optical stack layer.

17. The method of claim 11 in which depositing the second mirror layer comprises depositing at least one metal selected from aluminum, silver, and gold.

18. The method of claim 11 in which depositing the second mirror layer comprises selecting a thickness of the second mirror layer to thereby render the second mirror layer fully reflective.

19. The method of claim 11 in which depositing the second mirror layer comprises controlling a deposition condition to thereby produce the second mirror layer having a thickness in the range of about 80 Å

to about 1 Micron.

20. The method of claim 11, further comprising depositing a flexible metal conductor layer of a flex layer.

21. The method of claim 20 in which depositing the flexible metal conductor layer comprises depositing at least one metal selected from nickel, chromium, aluminum, and aluminum alloy.

22. The method of claim 11 in which depositing the sacrificial layer comprises depositing at least one material selected from molybdenum, silicon, titanium, tungsten, and germanium.

23. The method of claim 11 in which depositing the sacrificial layer comprises controlling a deposition condition to thereby produce the sacrificial layer having a thickness in the range of about 400 Å

to about 6,000 Å

.

24. The method of claim 11, further comprising:

removing at least a portion of the sacrificial layer to form a cavity.

25. The method of claim 11 in which forming the lift-off stencil comprises:

depositing a lift-off material over the sacrificial layer; and

covering the deposited lift-off material with a photoresist.

26. The method of claim 25 in which forming the lift-off stencil further comprises patterning the photoresist.

27. The method of claim 11 in which depositing the first mirror layer comprises forming a second lift-off stencil over a transparent substrate.

28. A display panel comprising an array of interferometric modulators made by a method 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 patterning 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.

29. A display device comprising:

the display panel of claim 28;

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.

30. The display device of claim 29 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.

31. The display device of claim 29 further comprising:

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

32. The display device of claim 31 wherein the image source module comprises at least one of a receiver, a transceiver, and a transmitter.

33. The display device of claim 29 further comprising:

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