Method for fabricating microelectromechanical optical display devices

• US 7,358,102 B2
• Filed: 03/30/2005
• Issued: 04/15/2008
• Est. Priority Date: 12/31/2004
• Status: Active Grant

• Current Assignee: AU Optronics Corporation, Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: AU Optronics Corporation
• Inventors: Lee, Chia-Sheng, Wong, Jia-Fam, Lin, Han-Tu
• Primary Examiner(s): Baumeister; B. William
• Assistant Examiner(s): Fulk; Steven J.
• Application Number:
  US11/093,498
• Publication Number:
  US 20060148262A1
• Time in Patent Office: 1,112 Days
• Field of Search: 438/29, 438/704, 257/432, 257/E21.232, 359/291
• US Class Current: 438/29
• 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

A Method of forming microelectromechanical optical display devices is provided. A sacrificial layer is formed above a substrate. A plurality of posts penetrating the sacrificial layer is formed. A reflective layer and a flexible layer are sequentially formed above the sacrificial layer and the posts. A photoresist layer is formed on part of the flexible layer. By performing wet etching using the photoresist layer as a mask, a portion of the flexible layer is removed to form a patterned flexible layer. The wet etching is stopped on the reflective layer. The photoresist layer is removed. By performing dry etching using the patterned flexible layer as a mask, a portion of the reflective layer is removed to form a patterned reflective layer. A mechanical layer is formed with the patterned flexible and reflective layers. The sacrificial layer is removed to release the mechanical layer.

Claims

1. A method of forming a microelectromechanical optical (MEMO) display device, comprising:

forming an optical stack layer on a substrate;

forming a sacrificial layer on the optical stack layer;

patterning the sacrificial layer to form a plurality of holes therein;

filling a supporting material in the holes to form a plurality of posts;

forming a reflective layer on the sacrificial layer and the posts;

forming a flexible layer on the reflective layer;

forming a photoresist layer on a portion of the flexible layer;

performing a wet etching using the photoresist layer as a mask to remove a portion of the flexible layer to form a patterned flexible layer, wherein the wet etching is stopped on the reflective layer;

removing the photoresist layer;

performing a dry etching using the patterned flexible layer as a mask to remove a portion of the reflective layer to form a patterned reflective layer, wherein a mechanical layer is formed with the patterned flexible layer and the patterned reflective layer; and

removing the sacrificial layer and thus the mechanical layer is supported by the posts.

2. The method according to claim 1, wherein the substrate is transparent.

3. The method according to claim 1, wherein formation of the optical stack layer comprises:

forming a transparent conductive layer on the substrate; and

forming a dielectric layer on the transparent conductive layer.

4. The method according to claim 1, wherein the sacrificial layer comprises molybdenum or silicon.

5. The method according to claim 1, wherein the posts comprise polymer.

6. The method according to claim 1, wherein the reflective layer comprises aluminum or silver and the flexible layer comprises nickel or titanium.

7. The method according to claim 1, wherein the wet etching employs HNO₃ solution.

8. The method according to claim 1, wherein the dry etching employs an etching gas comprising Cl₂, BCl₃, O₂, He and CF₄.

9. The method according to claim 1, wherein the dry etching employs an etching gas comprising SF₆, O₂, He and CF₄.

10. The method according to claim 1, wherein an etching selectivity of the flexible layer over the reflective layer is greater than 1 in the step of wet etching.

11. The method according to claim 10, wherein the etching selectivity is greater than or equal to 5.

12. The method according to claim 1, wherein removal of the photoresist layer is subsequent to formation of the patterned reflective layer.

23. The method according to claim 1, wherein sidewalls of the patterned flexible layer and the patterned reflective layer are substantially coplanar.

24. The method according to claim 1, wherein removing the photoresist layer is performed before performing the dry etching using the patterned flexible layer as the mask.

13. A method of forming a microelectromechanical optical (MEMO) display device, comprising:

forming an optical stack layer on a substrate; and

forming an optical device comprising a mechanical layer over the optical stack layer, wherein formation of the mechanical layer comprises;

sequentially forming a reflective layer and a flexible layer above the optical stack layer;

forming a photoresist layer on a portion of the flexible layer;

performing a wet etching using the photoresist layer as a mask to remove a portion of the flexible layer to form a patterned flexible layer, wherein the wet etching is stopped on the reflective layer;

removing the photoresist layer; and

performing a dry etching using the patterned flexible layer as a mask to remove a portion of the reflective layer to form a patterned reflective layer.

14. The method according to claim 13, wherein the substrate is transparent.

15. The method according to claim 13, wherein formation of the optical stack layer comprises:

forming a transparent conductive layer on the substrate; and

forming a dielectric layer on the transparent conductive layer.

16. The method according to claim 13, wherein the reflective layer comprises aluminum or silver, and the flexible layer comprises nickel or titanium.

17. The method according to claim 13, wherein the wet etching employs HNO₃ solution.

18. The method according to claim 13, wherein the dry etching employs an etching gas comprising Cl₂, BCl₃, O₂, He and CF₄.

19. The method according to claim 13, wherein the dry etching employs an etching gas comprising SF₆, O₂, He and CF₄.

20. The method according to claim 13, wherein an etching selectivity of the flexible layer over the reflective layer is greater than 1 in the step of wet etching.

21. The method according to claim 20, wherein the etching selectivity is greater than or equal to 5.

22. The method according to claim 13, wherein removal of the photoresist layer is subsequent to formation of the patterned reflective layer.