Transparent conductive stratiform coating of indium tin oxide

• US 20030035906A1
• Filed: 05/09/2001
• Published: 02/20/2003
• Est. Priority Date: 05/09/2001
• Status: Active Grant

• Current Assignee: Eastman Performance Films, LLC (Eastman Chemical Company)
• Original Assignee: CPFilms Inc. (Eastman Chemical Company)
• Inventors: Patel, Hitesh, Memarian, Hassan
• Granted Patent: US 6,743,488 B2
• Time in Patent Office: Days
• US Class Current: 428/1.3
• CPC Class Codes: C09K 2323/03 Viewing layer characterised by chemical composition
• CPC Class Codes: C09K 2323/035 Ester polymer, e.g. polycarbonate, polyacrylate or polyester
• CPC Class Codes: C09K 2323/04 Charge transferring layer characterised by chemical composition, i.e. conductive
• CPC Class Codes: C23C 14/0036 Reactive sputtering
• CPC Class Codes: C23C 14/086 of zinc, germanium, cadmium, indium, tin, thallium or bismuth
• CPC Class Codes: H01L 31/022466 made of transparent conductive layers, e.g. TCO, ITO layers
• CPC Class Codes: H01L 31/022475 composed of indium tin oxide [ITO]
• CPC Class Codes: H10K 50/81 Anodes
• CPC Class Codes: H10K 50/816 Multilayers, e.g. transparent multilayers
• CPC Class Codes: Y10T 428/24942 including components having same physical characteristic in differing degree

Abstract

A transparent electrically conductive device which includes an indium tin oxide film is improved by providing an indium tin oxide film which contains a graded stack of individual indium tin oxide layers wherein the atomic percent of tin in the layers can be individually selected. Each indium tin oxide layer of the film contains 1-99 atomic percent tin. Each layer is made by a physical vapor deposition process or by sputter coating. Preferably the film which contains a plurality of indium tin oxide layers is applied to a transparent flexible substrate such as a polymeric sheet. Optional primer layers, hardcoat layers and topcoat layers may be included in the device.

Claims

1. In a multi-layered electronic device which comprises a transparent substrate coated with at least one transparent electrically conductive film of indium tin oxide, wherein the improvement comprises:

said at least one indium tin oxide film having a proportion of indium to tin atoms which is nonuniform throughout the thickness of said film such that said indium and tin atoms are distributed throughout the thickness of said film to form a plurality of indium tin oxide layers, each of said layers having a finite thickness wherein the proportion of indium and tin is substantially uniform throughout said finite thickness;

with the proviso that the proportion of indium to tin in at least one of said layers is different from the proportion of indium to tin in another of said layers.

2. The device of claim 1 wherein the atomic percent of tin based upon the total content of indium and tin in each of the indium tin oxide layers is 1 atomic percent-99 atomic percent.

3. The device of claim 2 wherein said transparent substrate is a flexible polymeric sheet.

4. The device of claim 3 wherein said flexible polymeric sheet is selected from the group consisting of polyester, polysulfone, polycarbonate and polyurethane.

5. The device of claim 4 wherein said polyester is polyethylene terephthalate.

6. The device of claim 3 wherein each of said indium tin oxide layers of said film has a thickness of 5-10,000 angstroms.

7. The device of claim 3 wherein said film has a sheet resistance which varies from 1 to 10,000 ohms per square.

8. The device of claim 7 which has a visible light transparency which is greater than 75%.

9. The device of claim 5 wherein said polyethylene terephthalate is heat stabilized.

10. The device of claim 4 which includes a scratch resistant hardcoat layer located above and/or below said substrate whereby a hardcoat layer is interposed between said indium tin oxide film and said substrate.

11. The device of claim 10 wherein said hardcoat has a thickness in the range of 5,000 to 100,000 angstroms.

12. The device of claim 10 which includes a protective topcoat layer on a top surface of said device and/or a protective topcoat layer on a bottom surface of said device.

13. The device of claim 12 which comprises the sequence of layers:

protective topcoat/substrate/hardcoat/primer/indium tin oxide film/protective topcoat;

said primer of said primer layer being adhesive primer or a barrier primer.

14. The device of claim 12 which includes a primer layer in between any of the layers of said multilayered device;

said primer of said primer layer being adhesion primer or barrier primer.

15. The device of claim 14 which includes a plurality of primer layers.

16. The device of claim 15 wherein said adhesion primer layer is metal, metal nitride, metal oxide or metal carbide and said barrier primer layer is an organic compound.

17. The device of claim 16 wherein said adhesion primer layer has a thickness in the range of 5-10,000 angstroms and the barrier primer layer has a thickness in the range of 50-10,000 angstroms.

18. The device of claim 16 wherein the adhesion primer layer is selected from the group consisting of metal, oxide of said metal and nitride of said metal;

wherein said metal is selected from the group consisting of W, Ti, Cr, Ni, Cu, Zr, Hf, Ta, Al and Si.

19. The device of claim 18 wherein said adhesion primer layer is selected from the group consisting of TiO₂, Al₂O₃, Ta₂O₅, IZO, TiN, ZrN, TiC and W₂C.

20. The device of claim 14 wherein said at least one indium tin oxide film comprises a plurality of indium tin oxide films.

21. The device of claim 20 wherein said plurality of films includes at least one pair of films.

22. The device of claim 14 which contains a single indium tin oxide film.

23. The device of claim 22 wherein said film consists of a first indium tin oxide layer next to a second indium tin oxide layer wherein said second indium tin oxide layer is adjacent to said substrate or said primer layer;

or said second indium tin oxide layer is adjacent to said hardcoat and said hardcoat is adjacent to said substrate.

24. The device of claim 9 wherein said at least one film consists of a first indium tin oxide layer next to a second indium tin oxide layer;

said device including a scratch resistant hardcoat layer located above and/or below said substrate; and

a primer layer next to one or both sides of said film and/or next to one or both sides of said substrate, or said hardcoat layer or layers.

25. The device of claim 24 which contains a single indium tin oxide film.

26. The device of claim 25 wherein said indium tin oxide film has a thickness of 10-100,000 angstroms, a sheet resistance of 1-10,000 ohms per square and said device a visible light transparency which is greater than 75%.

27. The device of claim 9 wherein said at least one film consists of a lower indium tin oxide layer, a middle indium tin oxide layer and an upper indium tin oxide layer;

said middle indium tin oxide layer being coated onto a top surface of said lower indium tin oxide layer and said upper indium tin oxide layer being coated onto a top surface of said middle indium tin oxide layer;

said device including a scratch resistant hardcoat layer located above and/or below said substrate; and

a primer layer next to one or both sides of said film and/or next to one or both sides of said substrate or said hardcoat layer or layers.

28. The device of claim 24 which contains a single indium tin oxide film.

29. The device of claim 27 which includes an organic or inorganic protective topcoat layer on a top surface of said device and/or a protective topcoat layer on a bottom surface of said device.

30. The device of claim 29 wherein said protective topcoat layer is metal, metal oxide, metal nitride or metal carbide.

31. The device of claim 30 wherein said protective topcoat is:

metal selected from the group consisting of Pd, Au, Ni and Cr;

metal alloy selected from the group consisting of NiCr, AuAg, CuPd and CuAg;

metal oxide selected from the group consisting of SiO₂, TiO₂, Al₂O₃, IZO and Ta₂O₅;

metal nitride selected from the group consisting of TiN and Si₃N₄;

metal carbide selected from the group consisting of TiC and W₂C;

or

combinations of said metal, metal alloy, metal oxide, metal nitride or metal carbide.

32. The device of claim 31 wherein said protective topcoat has a thickness in the range of 5-5,000 angstroms.

33. The device of claim 29 wherein said protective topcoat is organic.

34. The device of claim 33 wherein the organic topcoat is applied in the form of an organo-titanium based solution.

35. The device of claim 34 wherein the organic topcoat has a thickness in the range of 10-100,000 angstroms.

36. The device of claim 4 wherein said at least one indium tin oxide film includes an indium tin oxide film above said substrate and an indium tin oxide film below said substrate;

said device further including one or more scratch resistant hardcoat layers, one or more primer layers and a protective topcoat layer on a top surface of said device and/or a protective topcoat layer on a bottom surface of said device.

37. An electronic apparatus which comprises the device of claim 1 as a component thereof;

said electronic apparatus being selected from the group consisting of transparent touch panels, electroluminescent lamps, personal digital assistants, pen entry devices, liquid crystal displays and organic light emitting devices.

38. The device of claim 4 wherein the thickness of each indium tin oxide layer of said at least one film is at least about 50 angstroms.

39. The device of claim 5 which contains a single indium tin oxide film;

said single indium tin oxide film having a lower indium tin oxide layer, a middle indium tin oxide layer and an upper indium tin oxide layer;

said middle indium tin oxide layer being coated onto a top surface of said lower indium tin oxide layer and said upper indium tin oxide layer being coated onto a top surface of said middle indium tin oxide layer;

said upper and lower indium tin oxide layers containing 95 atomic percent indium and 5 atomic percent tin; and

said middle layer containing 90 atomic percent indium and 10 atomic percent tin wherein the atomic percent of indium and tin in each layer is based upon the total content of indium and tin in said each layer.

40. The device of claim 5 which contains a single indium tin oxide film;

said single indium tin oxide film having a lower indium tin oxide layer, a middle indium tin oxide layer and an upper indium tin oxide layer;

said middle indium tin oxide layer being coated onto a top surface of said lower indium tin oxide layer and said upper indium tin oxide layer being coated onto a top surface of said middle indium tin oxide layer;

said upper and lower indium tin oxide layers containing 80 atomic percent indium and 20 atomic percent tin; and

said middle indium tin oxide layer containing 90 atomic percent indium and 10 atomic percent tin;

wherein the atomic percent of indium and tin in each layer is based upon the total content of indium and tin in said each layer.

41. The device of claim 5 which contains a single indium tin oxide film;

said single indium tin oxide film having a lower indium tin oxide layer, a middle indium tin oxide layer and an upper indium tin oxide layer;

said middle indium tin oxide layer being coated onto a top surface of said lower indium tin oxide layer and said upper indium tin oxide layer being coated onto a top surface of said middle indium tin oxide layer;

said middle and lower indium tin oxide layers containing 90 atomic percent indium and 10 atomic percent tin; and

said upper indium tin oxide layer containing 80 atomic percent indium and 20 atomic percent tin;

said atomic percent of indium and tin in each layer being based upon the total content of indium and tin in said each layer.

42. The device of claim 5 which contains a single indium tin oxide film;

said single indium tin oxide film having a lower indium tin oxide layer, a middle indium oxide layer and an upper indium tin oxide layer;

said middle indium tin oxide layer being coated onto a top surface of said lower indium tin oxide layer and said upper indium tin oxide layer being coated onto a top surface of said middle indium tin oxide layer;

said upper and lower indium tin oxide layers containing 90 atomic percent indium and 10 atomic percent tin; and

said middle indium tin oxide layer containing 80 atomic percent indium and 20 atomic percent tin;

wherein the atomic percent of indium and tin in each layer is based upon the total content of indium and tin in said each layer.

43. In a method of making an electronic device which comprises coating a transparent substrate with an electrically conductive transparent indium tin oxide film, wherein the improvement comprises:

forming a first transparent electrically conductive indium tin oxide layer from a first indium tin oxide source having an atomic percentage of indium and tin whereby said first indium tin oxide layer has an atomic percentage of indium and tin which is the same as the atomic percentage of indium and tin in said indium tin oxide source; and

then forming a second transparent electrically conductive indium tin oxide layer over said first indium tin oxide layer, said second indium tin oxide layer being formed from a second indium tin oxide source which has an atomic percentage of indium and tin which is different from the atomic percentage of indium and tin of said first indium tin oxide source whereby said second indium tin oxide layer has an atomic percentage of indium and tin which is the same as the proportion of indium and tin in said second indium tin oxide source;

said atomic percentage of tin in each indium tin oxide layer is in the range of 1 atomic percent-99 atomic percent wherein said atomic percentage of tin is based upon the total amount of indium and tin in said each indium tin oxide layer.

44. The method of claim 43 wherein said first and/or second sources of indium tin oxide is a vapor produced in a physical vapor deposition process, indium tin oxide produced during reactive sputtering with an InSn alloy target in an oxygen containing atmosphere, an InSn alloy target used in an oxidative reactive sputtering process, or an indium oxide and tin oxide containing composition.

45. The method of claim 44 wherein said transparent substrate comprises a flexible sheet of polyethylene terephthalate.

46. The method of claim 45 wherein;

a) the first indium tin oxide layer is produced by reactive sputter coating from a first InSn alloy target in an oxygen containing atmosphere and said second indium tin oxide layer is produced by reactive sputter coating from a second InSn alloy target in an oxygen containing atmosphere;

or

b) said first indium tin oxide layer is produced by sputter coating from a first indium tin oxide target and said second indium tin oxide layer is sputter coated from a second indium tin oxide target.

47. The method of claim 46 which further includes forming at least one additional transparent electrically conductive indium tin oxide layer over said second indium tin oxide layer so that said film comprises three or more transparent electrically conductive indium tin oxide layers;

said at least one additional indium tin oxide layer being produced by sputter coating from an InSn alloy target in an oxygen containing atmosphere or by sputter coating from an indium tin oxide target;

said at least one additional indium tin oxide layer having an atomic percent of tin in the range of 1 atomic percent to 99 atomic percent wherein said atomic percent is based upon the amount of tin relative to the total amount of indium and tin in said at least one indium tin oxide layer.

48. The method of claim 47 wherein said substrate includes at least one primer layer or at least one hardcoat layer or any combination of at least one primer layer and at least one hardcoat layer.

49. The method of claim 48 which further includes the step of coating a top surface of said device with a protective topcoat layer and/or the step of coating a bottom surface of said device with a protective topcoat layer.

50. The method of claim 48 wherein said polyethylene terephthalate sheet is passed from a feed roll to a wind-up roll through a plurality of sputter coating stations wherein each indium tin oxide layer is formed in a separate sputter coating station.

51. The method of claim 46 wherein said first indium tin oxide layer is produced by reactive sputter coating from a first InSn alloy target in an oxygen containing atmosphere and said second indium tin oxide layer is produced by reactive sputter coating from a second InSn alloy target in an oxygen containing atmosphere;

and the amount of oxygen in said atmosphere and the reactive deposition of oxide on the substrate is controlled by a plasma emission control monitor.

52. The product produced by the process of claim 43.

53. The product produced by the method of claim 47.