Methods for forming patterned structures
In general, in a first aspect, the invention features a method that includes forming a first layer comprising a first material over a surface of a second layer, wherein forming the first layer includes sequentially forming a plurality of monolayers of the second material over the surface of the second layer, the second layer comprises a plurality of rows of a second material extending along a first direction and spaced from one another in a second direction orthogonal to the first direction, and the first layer conforms to the surface of the second layer. The method further includes removing portions of the first layer to produce a plurality of rows of the first material extending along the first direction and spaced from one another in the second direction and removing portions of a third layer comprising a third material, where the portions correspond to intervals between the second plurality of rows so that removing the portions forms a plurality of rows of the third material extending along the first direction and spaced apart from one another. The first and second materials are different.
1. A method of forming patterned structures for optical devices, comprising:
using atomic layer deposition to form a first layer comprising a first material over a surface of a second layer, wherein forming the first layer comprises sequentially forming a plurality of monolayers of the first material over the surface of the second layer, wherein the second layer comprises a plurality of rows of a second material extending along a first direction and spaced from one another in a second direction orthogonal to the first direction, wherein the first layer conforms to the surface of the second layer, and wherein the first material includes a dielectric material having metal oxide; and
removing portions of the first layer to produce a plurality of rows of the first material extending along the first direction and spaced from one another in the second direction and to form an optical device that includes the metal oxide; and
removing portions of a third layer comprising a third material, where the portions of the third layer correspond to intervals between the plurality of rows of the second material so that removing the portions forms a plurality of rows of the third material extending along the first direction and spaced apart from one another,
wherein the first and second materials are different.
2. The method of claim 1 , wherein the optical device is selected from the list consisting of a polarizer, an optical filter, a beamsplitter, and a retarder, and the rows of the second material are arranged periodically in the second direction with a period Λ.
3. The method of claim 2 , wherein the rows of the first material are arranged periodically in the second direction with a period λ.
4. The method of claim 3 , wherein λ is smaller than Λ.
5. The method of claim 4 , wherein λ is about Λ/2.
6. The method of claim 2 , wherein Λ is about 200 nm or less.
7. The method of claim 2 , wherein Λ is about 150 nm or less.
8. The method of claim 1 , wherein a width in the second direction of each row of the second material is about Λ/4.
9. The method of claim 1 , wherein a thickness of the first layer in a third direction orthogonal to the first and second directions is about Λ/4.
10. The method of claim 1 , wherein the metal oxide of the first material includes TiO 2 .
11. The method of claim 1 , wherein the second material is an inorganic material.
12. The method of claim 1 , wherein the second material is a metal.
13. The method of claim 1 , wherein the second material is a dielectric material.
14. The method of claim 1 , wherein the third material is at least one of an inorganic material or an organic material.
15. The method of claim 1 , wherein the third material is a metal.
16. The method of claim 15 , wherein the metal is aluminum.
17. The method of claim 1 , wherein the rows of the second material are formed by:
exposing portions of a layer of a resist to radiation to produce an exposure pattern in the layer of the resist;
removing portions of the layer of the resist to produce a plurality of rows of the resist extending along the first direction and spaced apart from each other; and
removing portions of the second material that correspond to removed portions of the layer of the resist to form the rows of the second material.
18. The method of claim 1 , wherein removing portions of the first layer comprises etching the first layer.
19. The method of claim 18 , wherein the first layer is etched anisotropically.
20. The method of claim 1 , wherein removing portions of the third layer comprises etching the third layer.
21. The method of claim 20 , wherein the third material layer is etched with chlorine gas.
22. The method of claim 1 , wherein the rows of the third material form a grating with a grating period of about 100 nm or less.
23. The method of claim 1 , wherein the rows of the third material form a grating with a grating period of about 50 nm or less.
24. The method of claim 1 , further comprising depositing a fourth material between the rows of the third material, wherein the third and fourth materials are different.
25. The method of claim 1 , further comprising forming one or more additional layers over the rows of the third material.
26. The method of claim 1 , wherein the rows of the third material form a layer that is birefringent for light of wavelength A propagating through the layer along an axis, wherein λ is between 100 nm and 2,000 nm.
27. The method of claim 1 , wherein the first, second and third materials, and periodicity of the rows of the first, second and third materials are selected such that the device transmits about 50% or more of light of wavelength λ having a first polarization state incident on a layer along a path, and blocks about 80% or more of light of wavelength λ having a second polarization state incident on the layer along the path, the first and second polarization states being orthogonal, and λ is between about 100 nm and about 400 nm.
28. The method of claim 1 , further comprising forming a grating layer from the rows of the third material.
29. The method of claim 1 , wherein the first layer is an optical device grating formed from the dielectric material.
30. The method of claim 1 , wherein the first material includes a combination of TiO 2 and Al 2 O 3 .
31. The method of claim 1 , wherein the method further comprises:
removing portions of the second layer; and
removing the portions of the third layer corresponding to the removed portions of the resist layer prior to using the atomic layer deposition to form the first layer, wherein the second layer includes a resist layer.
32. The method of claim 31 , further comprising:
forming the first layer on remaining portions of the resist layer and the third layer, respectively.