Applications and fabrication techniques for large scale wire grid polarizers

• US 20060118514A1
• Filed: 11/28/2005
• Published: 06/08/2006
• Est. Priority Date: 11/30/2004
• Status: Active Grant

• Current Assignee: Agoura Technologies, Inc.
• Original Assignee: Agoura Technologies, Inc.
• Inventors: Little, Michael J., McLaughlin, Charles W.
• Granted Patent: US 7,561,332 B2
• Time in Patent Office: Days
• US Class Current: 216/41
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: G02B 5/3058 comprising electrically conductive elements, e.g. wire grids, conductive particles

Abstract

A wire grid polarizer may be fabricated by forming plurality of substantially-straight metallic lines of predetermined periodicity Λ on a thin film substrate A plurality of substantially straight nanometer-scale periodic surface relief structures is created on a surface of the substrate. The periodic surface relief structures cover a region greater than about 4 centimeters in length and greater than about 4 centimeters in width, wherein the periodicity Λ is between about 10 nanometers and about 500 nanometers. One or more layers of material are formed on the periodic relief structures. The one or more layers include one or more conductor materials that form the plurality of substantially straight metallic lines over a region of the substrate greater than about 4 centimeters in length and greater than about 4 centimeters in width.

Claims

1. A method for forming a plurality of substantially-straight metallic lines of predetermined periodicity Λ

on a thin film substrate, comprising the steps of;

creating a plurality of substantially straight nanometer-scale periodic surface relief structures on a surface of the substrate, wherein the periodic surface relief structures cover a region greater than about 4 centimeters in length and greater than about 4 centimeters in width, wherein the periodicity Λ

is between about 10 nanometers and about 500 nanometers; and

forming one or more layers of material on the periodic relief structures, the one or more layers including one or more conductor materials that form the plurality of substantially straight metallic lines over a region of the substrate greater than about 4 centimeters in length and greater than about 4 centimeters in width, wherein the periodicity Λ

is between about 10 nanometers and about 500 nanometers.

2. The method of claim 1 wherein the one or more layers are formed without patterning any of the one or more layers of material with photolithographic techniques.

3. The method of claim 1 wherein creating the nanometer-scale periodic surface relief structures includes elastically elongating, coating or treating the elongated surface, and recovering a thin film substrate to create the nanometer-scale periodic surface relief structures.

4. The method of claim 1 wherein creating the nanometer-scale periodic surface relief structures includes performing imprint lithography on the substrate.

5. The method of claim 1 wherein creating the nanometer-scale periodic surface relief structures includes performing step-and-repeat imprint lithography on the substrate.

6. The method of claim 1 wherein creating the nanometer-scale periodic surface relief structures includes step-and-repeat stamping or embossing the nanometer-scale periodic surface relief structures into the substrate with a mold.

7. The method of claim 4, 5, or 6, further comprising the step of obliquely depositing a metal to cover selected portions of the periodic relief structures to form the plurality of substantially straight metallic lines.

8. The method of claim 1 wherein said substrate is transparent.

9. The method of claim 1 wherein said substrate is made of a polymer material.

10. The method of claim 1 wherein said substrate comprises poly(dimethylsiloxene).

11. The method of claim 1 wherein said steps of forming one or more layers of material, creating nanometer-scale periodic surface relief structures and selectively forming said one or more materials include the steps of:

a) forming nanometer-scale periodic surface relief structures on a transparent substrate coated with a sacrificial coating;

b) obliquely depositing a masking material on the periodic surface relief structures;

c) fracturing the masking material in leeward valleys of the periodic surface relief structures;

d) etching exposed portions of the sacrificial coating to expose portions of the substrate;

e) coating remaining portions of the masking material over the sacrificial coating and the exposed portions of the substrate with a conductive metal;

f) removing the remaining portions of the sacrificial coating and corresponding portions of the masking material and conductor material leaving behind the plurality of substantially straight metallic lines of predetermined periodicity Λ

on the thin film substrate.

12. The method of claim 1 wherein said steps of forming one or more layers of material, creating nanometer-scale periodic surface relief structures and selectively etching said one or more materials include the steps of:

a) forming a layer of sacrificial material on a surface of said substrate;

b) buckling said surface of said substrate such that said surface assumes a repetitive undulating topology of periodicity Λ

;

d) depositing a masking layer of material at an oblique angle with respect to said buckled first layer so that said material of said masking layer is arranged into regions of alternating thickness of periodicity Λ

;

then

e) applying a uniaxial tensile force to said substrate so that said substrate is elongated to a sufficiently stressed length that said material of said masking layer fractures into a plurality of lines of periodicity Λ

′

;

then

f) removing regions of said sacrificial layer that lie between said lines of material of said masking layer;

then

g) depositing a metallic layer onto said structure whereby said metallic layer overlies said lines of said masking layer and exposed portions of said substrate;

then

h) removing said lines of material of said masking layer, underlying portions of said sacrificial layer and portions of said metallic layer that overlie said lines of material of said masking layer, leaving parallel lines of said metallic layer of periodicity Λ

′

that directly overlie said substrate; and

then

i) removing said uniaxial tensile force from said substrate whereby said substate is relaxed to substantially said unstressed length the periodicity of said lines of material of said metallic layer is reduced to Λ

.

13. The method of claim 12 wherein buckling said surface of said substrate such that said surface assumes a repetitive undulating topology of periodicity Λ

includes treating said surface of said substrate with a plasma surface treatment that results in said undulating topology.

14. The method of claim 12 wherein buckling said surface of said substrate such that said surface assumes a repetitive undulating topology of periodicity Λ

includes;

applying a first uniaxial tensile force to stress said substrate whereby said substrate is elongated from said unstressed length to a first stressed length;

then

forming a layer of sacrificial material on a surface of said substrate; and

removing said first uniaxial tensile force from said coated substrate whereby said substrate assumes substantially said unstressed length and said material of said sacrificial layer buckles to assume a repetitive undulating topology of periodicity Λ

.

15. The method of claim 12 wherein applying a uniaxial tensile force to said substrate includes passing the substrate through two spaced apart pairs of pinch rollers, wherein each pair of pinch rollers rotates with a different tangential speed.

16. The method of claim 1 wherein said steps of forming one or more layers of material, creating nanometer-scale periodic surface relief structures and selectively etching said one or more materials include the steps of:

a) applying a first uniaxial tensile force to stress said substrate whereby said substrate is elongated from said unstressed length to a first stressed length;

then

b) forming a layer of sacrificial material on a surface of said substrate;

then

c) removing said first uniaxial tensile force from said coated substrate whereby said substrate assumes substantially said unstressed length and said material of said sacrificial layer buckles to assume a repetitive undulating topology of periodicity Λ

;

then

d) depositing a masking layer of material at an oblique angle with respect to said buckled first layer so that said material of said masking layer is arranged into regions of alternating thickness of periodicity Λ

;

then

e) applying a second uniaxial tensile force that exceeds said first uniaxial tensile force to said substrate so that said substrate is elongated to a second stressed length exceeding said first stressed length whereby said material of said masking layer is fractured into a plurality of lines of periodicity Λ

′

;

then

f) removing regions of said sacrificial layer that lie between said lines of material of said masking layer;

then

g) depositing a metallic layer onto said structure whereby said metallic layer overlies said lines of said masking layer and exposes portions of said sacrificial layer;

then

h) removing said lines of material of said masking layer, underlying portions of said sacrificial layer and portions of said metallic layer that overlie said lines of material of said masking layer, leaving parallel lines of said metallic layer of periodicity Λ

′

that directly overlie said substrate; and

then

i) removing said second uniaxial tensile force from said substrate whereby said substate is relaxed to substantially said unstressed length the periodicity of said lines of material of said metallic layer is reduced to Λ

.

17. The method of claim 16, further including the step of removing said lines of material of said masking layer, underlying portions of said sacrificial layer and portions of said metallic layer that overlie said lines of material of said masking layer by a lift off process.

18. The method of claim 17 wherein said lift off process includes the step of applying water as solvent.

19. The method of claim 16 wherein said masking layer comprises metallic material.

20. The method of claim 16 wherein said masking layer comprises dielectric material.

21. The method of claim 16 the step of depositing said masking layer at an oblique angle includes vacuum deposition of said masking layer.

22. The method of claim 1 wherein said step of forming nanometer scale periodic surface relief structures includes the step of pattering the one or more layers of material including one or more conductor materials on the substrate with a nano-imprint roller having nanometer-scale linear features.

23. The method of claim 1 wherein one or more layers of material including one or more conductor materials on the substrate

25. The polarizer of claim 23 wherein said thin film substrate is transparent.

26. The polarizer of claim 23 wherein said thin film substrate is made of a polymer material.

27. The polarizer of claim 23 wherein said substrate comprises poly(dimethylsiloxene).

28. The polarizer of claim 23 wherein the plurality of substantially-straight metallic lines of predetermined periodicity Λ

are formed on the thin film substrate by the method of claim 1.

29. The polarizer of claim 23 wherein the plurality of substantially-straight metallic lines of predetermined periodicity Λ

are formed on the thin film substrate by the method of claim 12.

30. The polarizer of claim 23 wherein the plurality of substantially-straight metallic lines of predetermined periodicity Λ

are formed on the thin film substrate by the method of claim 16.

31. The polarizer of claim 23 wherein the lines cover a region approximately 4 centimeters to about 200 centimeters in length and approximately 4 centimeters to about 200 centimeters in width.

44. The apparatus of claim 40 wherein the plurality of substantially-straight metallic lines of predetermined periodicity Λ

are formed on the thin film substrate by the method of claim 1.

45. The apparatus of claim 40 wherein the plurality of substantially-straight metallic lines of predetermined periodicity Λ

are formed on the thin film substrate by the method of claim 12.

46. The apparatus of claim 40 wherein the plurality of substantially-straight metallic lines of predetermined periodicity Λ

are formed on the thin film substrate by the method of claim 16.

24. A wire grid polarizer, comprising:

a plurality of substantially-straight metallic lines of predetermined periodicity Λ

formed on a thin film substrate, wherein the lines cover a region greater than about 4 centimeters in length and greater than about 4 centimeters in width, wherein the periodicity Λ

is between about 10 nanometers and about 500 nanometers.

32. A direct view display apparatus, comprising

a source of backlight;

a liquid crystal array;

a wire grid polarizer disposed between the source of backlight and the liquid crystal array; and

a second polarizer, wherein the liquid crystal array is disposed between the wire grid polarizer and the second polarizer, wherein the second polarizer is configured to transmit light transmitted by the wire grid polarizer.

33. The apparatus of claim 32, further comprising an optical diffuser disposed between the source of backlight and the wire grid polarizer.

34. The apparatus of claim 32, further comprising an optical diffuser integrated into the backlight source.

35. The apparatus of claim 32, further comprising an optical diffuser integrated into the wire grid polarizer.

36. The apparatus of claim 32 wherein the second polarizer is a wire grid polarizer.

37. The apparatus of claim 32 wherein the second polarizer is an absorption-type polarizer.

38. The apparatus of claim 37, further comprising a third polarizer, wherein the third polarizer is an absorption-type polarizer, wherein the liquid crystal display is dispsed between the second and third polarizers, and wherein the wire grid polarizer is a tiled wire grid polarizer having a plurality of wire grid sections separated by spaces.

39. The apparatus of claim 38, wherein the wire grid sections are sufficiently close to each other that, when viewed through the third polarizer, the spaces appear sufficiently imperceptible for the purposes of a commercially acceptable display.

40. The apparatus of claim 32 wherein the wire grid polarizer includes a plurality of substantially-straight metallic lines of predetermined periodicity Λ

formed on a thin film substrate, wherein the lines cover a region approximately 4 centimeters to about 200 centimeters in length and approximately 4 centimeters to about 200 centimeters in width, wherein the periodicity Λ

is between about 10 nanometers and about 500 nanometers.

41. The apparatus of claim 40 wherein said thin film substrate is transparent.

42. The apparatus of claim 40 wherein said thin film substrate is made of a polymer material.

43. The apparatus of claim 40 wherein said substrate comprises poly(dimethylsiloxene).