Thin-film structure and method for producing the same

• US 20050122588A1
• Filed: 11/24/2004
• Published: 06/09/2005
• Est. Priority Date: 11/28/2003
• Status: Active Grant

• Current Assignee: Nippon Sheet Glass Company Limited
• Original Assignee: Nippon Sheet Glass Company Limited
• Inventors: Kunisada, Terufusa, Nakama, Kenichi, Kusaka, Satoru
• Granted Patent: US 7,113,338 B2
• Time in Patent Office: Days
• US Class Current: 359/585
• CPC Class Codes: C03C 17/3607 Coatings of the type glass/inorganic compound/metal
• CPC Class Codes: C03C 17/3647 in combination with other metals, silver being more than 50%
• CPC Class Codes: C03C 2217/77 Coatings having a rough surface
• CPC Class Codes: C03C 2218/113 by sol-gel processes
• CPC Class Codes: C03C 2218/154 by sputtering
• CPC Class Codes: G02B 5/3058 comprising electrically conductive elements, e.g. wire grids, conductive particles
• CPC Class Codes: G02F 1/133528 Polarisers
• CPC Class Codes: G02F 1/133548 Wire-grid polarisers

Abstract

A thin-film structure includes plate-shaped metals or plate-shaped structures in which a plate-shaped metal and a plate-shaped dielectric are in contact. The plate-shaped metal or structures are formed on a transparent base having a surface with line-shaped corrugated structures. The plate-shaped metals or structures are perpendicular to or oblique to the surface of the base. The thin-film structure has characteristics suitable for polarizers used in liquid crystal projectors and the like.

Claims

1. A thin-film structure comprising:

a base on which is disposed a plurality of parallel line-shaped corrugated structures;

a plurality of parallel plate-shaped metals provided on said base, said plate-shaped metals being disposed at a fixed angle with a surface of said base, and an end of each plate-shaped metal being in contact with said base along the direction of said line-shaped corrugated structure,

wherein an average gap (d) between said plate-shaped metals, a film thickness (H), and an average width (W), in terms of a working wavelength λ

, and an angle (θ

) relative to said base lie within the following ranges;

0.07λ

<

d<

0.20λ


0.15λ

<

H<

0.90λ


0.05λ

<

W<

0.18λ


0 degθ

25 deg.

2. The thin-film structure as described in claim 1 wherein said film thickness (H) is within the range:

0.15λ

<

H<

0.50λ

.

3. The thin-film structure as described in claim 1 wherein:

said base is formed from a substrate on which the plurality of parallel line-shaped corrugated structures are disposed and a transparent dielectric film of at least one layer is disposed on said substrate; and

a surface shape of said line-shaped corrugated structures disposed on said substrate is different from a surface shape of said transparent dielectric film.

4. The thin-film structure as described in claim 3 wherein said transparent dielectric film is thicker at a crest of said corrugated structure on the substrate than at a trough of said corrugated structure.

5. The thin-film structure as described in claim 1 wherein:

said line-shaped corrugated structures has a cross-section that forms a periodic arrangement of similar trapezoids, each trapezoid on either side has a bottom base that meets said substrate surface in a single line; and

ends of said plate-shaped metals are provided on said corrugated structures corresponding to legs of said trapezoids.

6. The thin-film structure as described in claim 5 wherein said ends of said plate-shaped metals are in contact with two planes of said corrugated structures corresponding to two legs on either side of the top of said trapezoids.

7. The thin-film structure as described in claim 6 wherein said plate-shaped metals are arranged at a twice the period of said trapezoids.

8. The thin-film structure as described in claim 1 wherein said line-shaped corrugated structures are formed by pressing a mold engraved with a plurality of parallel line-shaped corrugated structures against a sol or a gel of a transparent material applied to a flat substrate surface and heating said substrate.

9. The thin-film structure as described in claim 1 wherein said line-shaped corrugated structures are formed by scatching a substrate surface using an abrasive.

10. The thin-film structure as described in claim 1 wherein a plate-shaped dielectric is in contact with one side of a surface of said plate-shaped metal.

11. The thin-film structure as described in claim 10 wherein said plate-shaped dielectric as its main component comprises silicon dioxide.

12. The thin-film structure as described in claim 1 wherein gaps between said plate-shaped metals and gaps between said plate-shaped metals and said plate-shaped dielectrics are filled and covered with a transparent dielectric having an index of refraction of no more than 1.6.

13. The thin-film structure as described in claim 1 wherein a transparent dielectric film covers an upper surface of said thin-film structure.

14. The thin-film structure as described in claim 1 wherein said plate-shaped metals comprise silver, aluminum, copper, platinum, or an alloy of these metals.

15. The method for making a thin-film structure comprising the steps of:

providing a base formed from a substrate having thereron a plurality of parallel line-shaped corrugated structures;

forming a transparent dielectric film on said substrate by applying ions or atoms or clusters of an element for forming a dielectric from a direction that is oblique relative to a normal of said substrate and at a fixed angle relative to the direction of said line-shaped corrugated structures formed on said substrate, while at the same time, applying ions or atoms or clusters of an element for forming a dielectric from an opposite direction on the other side of a normal plane containing said lines on said substrate; and

subsequently forming a film by applying metal ions or metal atoms or metal clusters from an oblique direction relative to a normal of said substrate surface and at a fixed angle relative to the direction of said line-shaped corrugated structures.