Small-pitch wire grid polarizer

Patent metadata

Field	Value
Publication number	US-10353127-B2
Application number	US-201815948770-A
Country	US
Kind code	B2
Filing date	Apr 9, 2018
Priority date	Aug 24, 2015
Publication date	Jul 16, 2019
Grant date	Jul 16, 2019

Abstract

The wire grid polarizer (WGP) comprises an array of parallel, elongated nanostructures located over a surface of a transparent substrate and a plurality of spaces, including a space between adjacent nanostructures. Each of the nanostructures can include (1) a plurality of parallel, elongated wires located on the substrate, including an inner-pair located between an outer-pair; (2) lateral-gaps between each wire of the outer-pair and an adjacent wire of the inner-pair; (3) and a center-gap between the two wires of the inner-pair.

First claim

What is claimed is:

1. A method of making a wire grid polarizer (WGP), the method comprising the following steps:
providing an array of parallel, elongated support ribs located over a transparent substrate and spaces between the support ribs, the spaces being solid-material-free;
conformal coating the substrate and the support ribs with a first-layer while maintaining solid-material-free at least a portion of the spaces between the support ribs;
etching the first-layer to remove horizontal segments and leaving an array of inner-pairs of parallel, elongated wires along sides of the support ribs, each wire of each inner-pair being separate from the other wire of the inner-pair;
conformal coating the substrate and the support ribs with a second-layer while maintaining solid-material-free at least a portion of the spaces between the support ribs;
etching the second-layer to remove horizontal segments and leaving middle-pairs, the middle-pairs being an array of parallel, elongated wires, each wire of each middle-pair being separated from the other wire of the middle-pair by wires of the inner-pair;
conformal coating the substrate and the support ribs with a third-layer while maintaining solid-material-free at least a portion of the spaces between the support ribs;
etching the third-layer to remove horizontal segments and leaving outer-pairs, the outer-pairs being an array of parallel, elongated wires along sides of the support ribs, each wire of each outer-pair being: spaced apart with respect to the other wire of the outer-pair; and spaced apart with respect to wires of the inner-pair by wires of a middle-pair, the wires of the middle-pair being formed of material of the second-layer;
filling spaces between the support ribs with a solid material; and
etching the solid material, the support ribs, and the middle-pair to form: lateral-solid-material-free-regions between at least a portion of each wire of each outer-pair and at least a portion of an adjacent wire of the inner-pair; and center-solid-material-free-regions between at least a portion of the two wires of each inner-pair.

2. The method of claim 1 , wherein the middle-pair and the solid material are both made of the same material.

3. The method of claim 1 , wherein etching the support ribs, the middle-pair, and the solid material include:
etching through the support ribs then into the transparent substrate between the two wires of each inner-pair;
etching away completely the middle-pair and continuing to etch into the transparent substrate between each wire of each outer-pair an adjacent wire of the inner-pair; and
etching the solid material and continuing to etch into the transparent substrate.

4. The method of claim 1 , wherein the center-solid-material-free-regions extend from a distal-end, farther from the transparent substrate, to a proximal-end, closer to the transparent substrate, of an adjacent wire of the inner-pair, and extend beyond the proximal-end into the transparent substrate for a distance of at least 10% of a thickness of the adjacent wire of the inner-pair.

5. The method of claim 1 , wherein the center-solid-material-free-regions extend for 70% to 98% of a distance from a distal-end, farther from the transparent substrate, towards a proximal-end, closer to the transparent substrate, of an adjacent wire of the inner-pair.

6. The method of claim 1 , further comprising etching the transparent substrate between adjacent support ribs, forming base-ribs, each base-rib having one of the inner-pairs and one of the outer-pairs thereon.

7. The method of claim 1 , further comprising etching the transparent substrate between adjacent support ribs, forming base-ribs, each base-rib having one of the inner-pairs and one of the outer-pairs thereon, and forming a solid-material-free space between adjacent base-ribs, each solid-material-free space:
extending from a distal-end, farther from the transparent substrate, towards a proximal-end, closer to the transparent substrate, of an adjacent wire of the outer-pair; and
extending beyond the proximal-end into the transparent substrate for a distance of at least 15% of a thickness of the adjacent wire of the outer-pair.

8. The method of claim 1 , wherein the lateral-solid-material-free-regions extend for at least 80% of a distance from a distal-end, farther from the transparent substrate, towards a proximal-end, closer to the transparent substrate, of an adjacent wire of the inner-pair.

9. The method of claim 1 , wherein the lateral-solid-material-free-regions extend for 70% to 98% of a distance from a distal-end, farther from the transparent substrate, towards a proximal-end, closer to the transparent substrate, of an adjacent wire of the inner-pair.

10. The method of claim 1 , wherein etching the support ribs includes forming the center-solid-material-free-region from a distal-end of the inner-pair farthest from the transparent substrate to a proximal-end of the inner-pair closest to the transparent substrate.

11. The method of claim 1 , wherein one of the first-layer or the third-layer is reflective and the other of the first-layer or the third-layer is absorptive.

12. The method of claim 11 , wherein the second-layer is transparent.

13. The method of claim 1 , wherein the second-layer is made of a different material than the first-layer and the third-layer is made of a different material than the first-layer or the second-layer.

14. A method of making a wire grid polarizer (WGP), the method comprising the following steps:
providing an array of parallel, elongated support ribs located over a transparent substrate and spaces between the support ribs, the spaces being solid-material-free;
conformal coating the substrate and the support ribs with a first-layer while maintaining solid-material-free at least a portion of the spaces between the support ribs;
etching the first-layer to remove horizontal segments and leaving an array of inner-pairs of parallel, elongated wires along sides of the support ribs, each wire of each inner-pair being separate from the other wire of the inner-pair, and using the inner-pair as a mask and etching into the substrate;
conformal coating the substrate and the support ribs with a second-layer while maintaining solid-material-free at least a portion of the spaces between the support ribs;
etching the second-layer to remove horizontal segments and leaving middle-pairs, the middle-pairs being an array of parallel, elongated wires, each wire of each middle-pair being separated from the other wire of the middle-pair by wires of the inner-pair;
conformal coating the substrate and the support ribs with a third-layer while maintaining solid-material-free at least a portion of the spaces between the support ribs;
etching the third-layer to remove horizontal segments and leaving outer-pairs, the outer-pairs being an array of parallel, elongated wires along sides of the support ribs, each wire of each outer-pair being: spaced apart with respect to the other wire of the outer-pair; and spaced apart with respect to wires of the inner-pair by wires of a middle-pair, the wires of the middle-pair being formed of material of the second-layer; and
etching the support ribs and the middle-pair to form: lateral-solid-material-free-regions between at least a portion of each wire of each outer-pair and at least a portion of an adjacent wire of the inner-pair; and center-solid-material-free-regions between at least a portion of the two wires of each inner-pair.

15. The method of claim 14 , wherein an order of the steps is: providing the array of parallel, elongated support ribs; conformal coatin

Assignees

• Moxtek Inc

Inventors

• Wang Bin
• Li Hua
• Bowers Brian

Classifications

• G02B5/1857

  using exposure or etching means, e.g. holography, photolithography, exposure to electron or ion beams · CPC title

• G02B26/00

  Optical devices or arrangements for the control of light using movable or deformable optical elements (control of light by modification of the optical properties of the media of the elements involved therein G02F1/00) · CPC title

• G02B5/3058 Primary

  comprising electrically conductive elements, e.g. wire grids, conductive particles · CPC title

• G02B6/136

  by etching · CPC title

• G02B5/00

  Optical elements other than lenses (light guides G02B6/00; optical logic elements G02F3/00) · CPC title