FINE PITCH WIRE GRID POLARIZER

• US 20120250154A1
• Filed: 09/02/2011
• Published: 10/04/2012
• Est. Priority Date: 09/21/2010
• Status: Active Grant

• Current Assignee: Moxtek (Polatechno Co.,Ltd.)
• Original Assignee: Moxtek (Polatechno Co.,Ltd.)
• Inventors: Davis, Mark Alan
• Granted Patent: US 8,611,007 B2
• Time in Patent Office: Days
• US Class Current: 359/485.05
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G02B 5/3058 comprising electrically conductive elements, e.g. wire grids, conductive particles
• CPC Class Codes: Y10T 428/2457 Parallel ribs and/or grooves

Abstract

A fine pitch wire grid polarizer can have a pitch of less than 80 nanometers and a protective layer on the wires, by anisotropically etching the wire grid polarizer to form two parallel, elongated rods substantially located at corners where the wires contacted the substrate. The rods can be polarizing elements. A wire grid polarizer can have a repeated pattern of groups of parallel elongated wires disposed over a substrate. Each group of elongated wires comprises at least three wires. At least one wire at an interior of each group can be taller by more than about 10 nm than outermost wires of each group. Wires of a wire grid polarizer can be a byproduct of an etch reaction. A multi-step wire grid polarizer can comprise a base with a plurality of parallel multi-step ribs disposed on the base and a coating disposed along vertical surfaces of the steps.

Claims

1. A wire grid polarizer comprising:

a. a substrate;

b. an array of parallel, elongated wires disposed on the substrate; and

c. the wires having a pitch of less than 80 nanometers.

2. The wire grid polarizer of claim 1, wherein the wires have a width less than 35 nanometers.

3. The wire grid polarizer of claim 1, wherein the wires have a pitch of 8 to 85 nanometers.

4. A method of making the wire grid polarizer of claim 1, the method comprising:

a. obtaining a wire grid polarizer having an array of parallel, elongated wires disposed on a substrate, the wires having a protective layer disposed at a surface of the wires;

b. anisotropically etching the wire grid polarizer to form two parallel, elongated rods substantially located at corners where the wires contacted the substrate.

5. A polarizer, comprising:

a. a substrate;

b. a repeated pattern of groups of parallel elongated wires disposed over the substrate;

c. each group of elongated wires comprising at least three wires;

d. at least one wire at an interior of each group is taller by more than 10 nm than outermost wires of each group; and

e. a distance between the outermost wires in each group is less than 1 micrometer.

6. The polarizer of claim 5, wherein the distance between the outermost wires in each group is less than 100 nanometers.

7. The polarizer of claim 5, wherein a width of the wires is less than 20 nm.

8. The polarizer of claim 5, wherein a minimum pitch of adjacent wires is less than 40 nm.

9. The polarizer of claim 5, wherein the wires comprise a material that is a byproduct of an etch reaction.

10. The polarizer of claim 5, wherein each group comprises at least four wires and a distance between two center wires is different than a distance between an outermost wire and an adjacent center wire by more than about 3 nm.

11. A method for making the polarizer of claim 5, the method comprising:

a. applying a resist over a base;

b. patterning the resist and creating resist widths;

c. performing an isotropic etch of the base and etching both vertically into the base laterally outside the resist and horizontally under the resist leaving a stem, having vertical sidewalls, under the resist;

d. allowing etch redeposition along the vertical sidewalls of the stem creating etch redeposition wires;

e. performing an anisotropic etch and etching vertically into the base outside the resist leaving a bottom step, having vertical sidewalls, in the base;

f. allowing etch redeposition along the vertical sidewalls of the bottom step and creating etch redeposition wires.

12. The method of claim 11, further comprising etching to remove the resist, substantially remove the base between etch redeposition wires, and leaving at least three separate etch redeposition wires for every original resist width.

13. The method of claim 11, wherein the resist widths are less than about 100 nm.

14. A nanometer sized multi-step device, comprising:

a. a base;

b. a plurality of parallel multi-step ribs disposed on the base;

c. each rib comprising multiple adjacent steps on each side thereof, the multiple adjacent steps comprising;

i. an upper step with a top horizontal surface flanked by upper vertical surfaces; and

ii. at least one pair of lower steps having two horizontal surfaces on opposite sides of the upper step, and flanked by lower vertical surfaces;

d. a coating along the vertical surfaces of the upper step and the at least one pair of lower steps; and

e. the coating along the vertical surface of any step is separate from the coating along a vertical surface of an adjacent step.

15. The device of claim 14, wherein the at least one pair of lower steps comprises at least two pairs of lower steps.

16. The device of claim 14, wherein the upper and lower steps are at different elevational heights defining a cross-sectional stepped pyramid shape.

17. The device of claim 14, further comprising wires which are:

a. attached to the base;

b. physically separate from the multi-step ribs; and

c. substantially parallel with the multi-step ribs and located between adjacent multi-step ribs.

18. The device of claim 14, wherein the wires comprise etch redeposition material.

19. A method for making the device of claim 14, the method comprising:

a. forming multi-step ribs, the ribs attached to a base;

b. coating the surface of the base and steps; and

c. removing coating on horizontal surfaces while leaving coating on vertical surfaces.

20. The method of claim 19, wherein the method for forming multi-step ribs in a base comprises:

a. applying a resist onto the base;

b. patterning the resist to create resist widths;

c. performing a first isotropic etch and etching both vertically into the base laterally outside the resist and horizontally under the resist;

d. performing at least one additional isotropic etch that is less isotropic than the previous isotropic etch and etching both vertically into the base laterally outside the resist and horizontally under the resist;

e. performing an anisotropic etch to etch into the base laterally outside the resist and to remove the resist.