Zinc-based film manipulation for an optical filter

• US 20070242359A1
• Filed: 04/14/2006
• Published: 10/18/2007
• Est. Priority Date: 04/14/2006
• Status: Active Grant

• Current Assignee: Southwall Technologies, Inc. (Eastman Chemical Company)
• Original Assignee: Southwall Technologies, Inc. (Eastman Chemical Company)
• Inventors: Boman, Lee, Thielsch, Roland, Boehme, Thomas, Stoessel, Chris
• Granted Patent: US 7,508,586 B2
• Time in Patent Office: Days
• US Class Current: 359/585
• CPC Class Codes: C03C 17/28 with organic material C03C17/34, C03C17/44 take precedence
• CPC Class Codes: G02B 5/282 reflecting for infrared and transparent for visible light, e.g. heat reflectors, laser protection
• CPC Class Codes: G02B 5/284 of etalon type comprising a resonant cavity other than a thin solid film, e.g. gas, air, solid plates etalons for fibre optic multiplexing G02B6/29358; etalons for spectral measurement G01J3/26

Abstract

An optical filter is formed of a layer stack that includes metallic layers and dielectric layers, with at least one dielectric layer being defined by more than one zinc-based film. These zinc-based films have different percentages of zinc. The selections of the percentages are based upon the positions of the films within the dielectric layer. An unexpectedly low sheet resistance is available if the zinc-based film that immediately precedes forming a metallic layer has a percentage of zinc in the range of 80 percent to next to 100 percent. Process stabilization and manufacturing cost are provided by placing the percentage of the lower zinc-based film closer to 50 percent (25-75). Process stabilization is further enhanced by providing an indium-based film within the dielectric layer adjacent to the metallic layer.

Claims

1. A method of providing an optical filter comprising:

forming a layer stack on a substrate such that said layer stack includes metallic layers and dielectric layers, including defining at least one said dielectric layer by;

forming a first zinc-based film, including selecting a first percentage of zinc in said first zinc-based film based upon factors that include process stabilization in forming zinc-based films; and

forming a second zinc-based film, including selecting a second percentage of zinc in said second zinc-based film based upon factors that include establishing target properties of a seeding layer for a subsequently formed said metallic layer, said second percentage being intentionally greater than said first percentage.

2. The method of claim 1 wherein defining said at least one dielectric layer further includes forming an indium-based film prior to forming said first and second zinc-based layers and subsequent to forming one of said metallic layers, such that said at least one dielectric layer includes a sequence of (a) said indium-based film, (b) said first zinc-based film and (c) said second zinc-based film.

3. The method of claim 2 wherein said metallic layers include silver, said indium-based film being formed as indium oxide in a hydrogen enriched environment.

4. The method of claim 1 wherein said first and second zinc-based films are sputter deposited as zinc-tin films to form zinc-tin oxide layers of low absorption in a reactive sputter process.

5. The method of claim 1 wherein selecting said first percentage of zinc includes selecting within the range of 25 percent to 75 percent and wherein selecting said second percentage includes selecting within the range of 80 percent to 100 percent.

6. The method of claim 1 wherein forming said layer stack includes providing an alternating pattern of said dielectric and metallic layers, with one of said dielectric layers being closest to said substrate within said layer stack.

7. The method of claim 6 wherein forming said layer stack includes providing five said dielectric layers and four said metallic layers.

8. The method of claim 7 wherein said metallic layer is silver or a silver alloy and each said dielectric layer is formed to include an indium oxide film nearest to said substrate within said dielectric layer.

9. The method of claim 1 further comprising providing said substrate as a flexible transparent member for use on a plasma display panel.

10. A filtering arrangement comprising:

a transparent substrate; and

a layer stack on said substrate, said layer stack including;

a first metallic layer;

first and second dielectric layers on opposite sides of said first metallic layer, said first dielectric layer being nearer to said substrate than said second dielectric layer, each said dielectric layer including a first zinc-based film and including a second zinc-based film with a greater percentage of zinc than said first zinc-based film so as to function as a seed film for metal of said first metallic layer, said second dielectric layer including an indium-based film between said first metallic layer and said first zinc-based film; and

a repeating pattern of an additional said metallic layer and an additional said dielectric layer to achieve a target sheet resistance.

11. The filtering arrangement of claim 10 wherein said percentage of zinc in said second zinc-based film is in the range between 80 percent and 100 percent.

12. The filtering arrangement of claim 11 wherein a percentage of zinc in said first zinc-based film is in the range of 25 percent to 75 percent.

13. The filtering arrangement of claim 11 wherein said first and second metallic layers are silver or a silver alloy and said first and second zinc-based layers are zinc-tin layers.

14. The filtering arrangement of claim 10 wherein said first zinc-based film includes an indium-based film between said substrate and said first zinc-based film.

15. The filtering arrangement of claim 10 wherein said substrate is attached to a plasma display panel.

16. The filtering arrangement of claim 10 wherein said filtering arrangement has a total of four said metallic layers and five said dielectric layers.

17. A method of forming an optical filter comprising:

forming a plurality of layers on a transparent substrate such that target optical properties are achieved, including sputter depositing at least one said layer to include a zinc-based film in which a percentage of zinc is intentionally less than one hundred percent and is greater than eighty percent; and

attaching said substrate to one of a plasma display panel or a window of a vehicle.

18. The method of claim 17 wherein said percentage is approximately ninety percent.

19. The method of claim 17 wherein said zinc-based film is oxidized zinc tin.

20. The method of claim 17 wherein said zinc-based film is oxidized ZnAl.