Coated article with ion treated overcoat layer and corresponding method

• US 20060008656A1
• Filed: 06/25/2004
• Published: 01/12/2006
• Est. Priority Date: 06/25/2004
• Status: Active Grant

• Current Assignee: Guardian Glass LLC (KOCH Industries Incorporated)
• Original Assignee: Guardian Industries Corporation (KOCH Industries Incorporated)
• Inventors: Veerasamy, Vijayen S.
• Granted Patent: US 7,585,396 B2
• Time in Patent Office: Days
• US Class Current: 428/434
• CPC Class Codes: B32B 17/10036 comprising two outer glass sheets
• CPC Class Codes: B32B 17/10174 Coatings of a metallic or dielectric material on a constituent layer of glass or polymer
• CPC Class Codes: B32B 17/10761 containing vinyl acetal
• CPC Class Codes: C03C 17/36 at least one coating being a metal
• CPC Class Codes: C03C 17/3626 one layer at least containing a nitride, oxynitride, boronitride or carbonitride
• CPC Class Codes: C03C 17/3639 Multilayers containing at least two functional metal layers
• CPC Class Codes: C03C 17/3644 the metal being silver
• CPC Class Codes: C03C 17/366 Low-emissivity or solar control coatings
• CPC Class Codes: C03C 17/3681 the multilayer coating being used in glazing, e.g. windows or windscreens
• CPC Class Codes: C03C 17/3694 one layer having a composition gradient through its thickness
• CPC Class Codes: C03C 2217/78 Coatings specially designed to be durable, e.g. scratch-resistant
• CPC Class Codes: C03C 2218/154 by sputtering
• CPC Class Codes: C03C 2218/326 Nitriding
• CPC Class Codes: C03C 23/0055 by ion implantation
• CPC Class Codes: C23C 14/0652 Silicon nitride
• CPC Class Codes: C23C 14/5833 Ion beam bombardment
• CPC Class Codes: C23C 14/586 Nitriding

Abstract

A coated article is provided that may be used as a vehicle windshield, insulating glass (IG) window unit, or the like. Ion beam treatment is performed on a layer(s) of the coating. For example, an overcoat layer (e.g., of silicon nitride) of a low-E coating may be ion beam treated in a manner so as to cause the ion beam treated layer to include (a) nitrogen-doped Si₃N₄, and/or (b) nitrogen graded silicon nitride. It has been found that this permits durability of the coated article to be improved.

Claims

1. A method of making a coated article, the method comprising:

providing a glass substrate;

forming a layer comprising silver on the glass substrate;

forming a layer comprising silicon nitride on the substrate over the layer comprising silver, wherein the layer comprising silicon nitride is formed on the substrate by at least sputtering a target comprising silicon; and

ion beam treating the layer comprising silicon nitride in a manner so as to cause the layer comprising silicon nitride to be nitrogen graded so that a portion of the layer comprising silicon nitride further from the glass substrate has a higher nitrogen content than does a portion of the layer closer to the glass substrate.

2. The method of claim 1, further comprising sputtering at least one dielectric layer on the substrate so as to be located between the substrate and the layer comprising silver, wherein the at least one dielectric layer comprises at least one of silicon nitride and a metal oxide, and wherein the layer comprising silicon nitride which is subjected to the ion beam treating is an outermost layer of a coating supported by the glass substrate.

3. The method of claim 1, further comprising forming at least a layer comprising NiCr on the substrate over at least the layer comprising silver so as to be located between the layer comprising silver and the layer comprising silicon nitride.

4. The method of claim 1, wherein said ion beam treating includes ion beam treating at least part of the layer comprising silicon nitride with at least nitrogen ions, and wherein an outermost 20 Å

thick portion of the layer comprising silicon nitride has at least a 5% higher nitrogen content than an innermost 20 Å

thick portion of the layer comprising silicon nitride.

5. The method of claim 1, wherein said ion beam treating further causes the silicon nitride to comprise nitrogen-doped Si₃N₄.

6. The method of claim 1, wherein said ion beam treating includes using an energy of at least about 550 eV per N₂⁺ ion.

7. The method of claim 1, wherein said ion beam treating includes using an energy of from about 600 to 1,100 eV per N₂⁺ ion.

8. The method of claim 1, wherein the layer comprising silicon nitride following said ion beam treating has compressive stress of from 50 MPa to 2 GPa.

9. The method of claim 1, further comprising heat treating the coated article in a manner sufficient for at least one of tempering and heat bending, so that following said heat treating the coated article has a visible transmission of at least 70% and a sheet resistance (R_s) of no greater than 5.5 ohms/square.

10. The method of claim 1, further comprising heat treating the coated article in a manner sufficient for at least one of tempering and heat bending, so that following said heat treating the coated article has a visible transmission of at least 75% and a sheet resistance (R_s) of no greater than 2.5 ohms/square.

11. The method of claim 1, wherein prior to any optional heat treating, the coated article in monolithic form has a visible transmission of at least 70% and a sheet resistance (R_s) of no greater than 6.0 ohms/square.

12. The method of claim 1, further comprising forming a layer comprising zinc oxide on the glass substrate, so that the layer comprising silver is located over and directly contacting the layer comprising zinc oxide.

13. The method of claim 1, further comprising forming the following layers on the glass substrate in the following order:

a) forming a layer comprising silicon nitride on the glass substrate;

b) forming a layer comprising zinc oxide on the glass substrate over at least the layer comprising silicon nitride formed in step a);

c) forming said layer comprising silver so as to contact an upper surface of the layer comprising zinc oxide;

d) forming a layer comprising tin oxide on the substrate and over at least the layer comprising silver;

e) forming another layer comprising zinc oxide on the substrate and over at least the layer comprising tin oxide;

f) forming another layer comprising silver on the substrate so as to contact an upper surface of the another layer comprising zinc oxide form in step e);

g) forming said layer comprising silicon nitride that is ion beam treated on the substrate over at least the another layer comprising silver.

14. The method of claim 1, wherein the layer comprising silicon nitride further comprises from about 1-10% aluminum, and wherein said ion beam treating comprises ion beam treating the layer comprising silicon nitride after the layer comprising silicon nitride has been formed by only sputtering.

15. A method of making a coated article, the method comprising:

providing a substrate;

forming a layer comprising silicon nitride on the substrate; and

ion beam treating the layer comprising silicon nitride in a manner so as to cause a portion of the layer comprising silicon nitride further from the substrate to have a higher nitrogen content than does a portion of the layer closer to the substrate.

16. The method of claim 15, further comprising sputtering at least one dielectric layer and at least one IR reflecting layer, wherein the dielectric layer is located between the substrate and the IR reflecting layer and wherein the layer comprising silicon nitride is located on the substrate over the IR reflecting layer.

17. The method of claim 15, wherein said ion beam treating further causes the silicon nitride to comprise nitrogen-doped Si₃N₄.

18. The method of claim 15, wherein the coated article has a visible transmission of at least 70% and a sheet resistance (R_s) of no greater than 5.5 ohms/square.

19. The method of claim 15, further comprising heat treating the coated article in a manner sufficient for at least one of tempering and heat bending, so that following said heat treating the coated article has a visible transmission of at least 75% and a sheet resistance (R_s) of no greater than 2.5 ohms/square.

20. A window comprising the coated article made according to claim 15.

21. The method of claim 15, wherein the layer comprising silicon nitride is an overcoat layer which is an uppermost layer of the coated article.

22. A method of making a coated article, the method comprising:

providing a glass substrate;

sputtering a layer comprising silver on the glass substrate;

sputtering a layer comprising silicon nitride on the glass substrate over the layer comprising silver; and

ion beam treating the layer comprising silicon nitride using at least nitrogen ions so that the ion beam treated layer comprising silicon nitride comprises nitrogen-doped Si₃N₄.

23. The method of claim 22, wherein the layer comprising silicon nitride is an overcoat layer which is an uppermost layer of the coated article.

24. The method of claim 22, wherein said ion beam treating is performed in a manner so as to reduce tensile stress of the layer comprising silicon nitride so that tensile stress of the layer comprising silicon nitride is from 0 to 25 MPa following the ion beam treating.

25. The method of claim 22, further comprising forming at least one dielectric layer on the substrate so as to be located between the substrate and the layer comprising silver, and sputtering at least a contact layer on the substrate over at least the layer comprising silver so as to be located between the layer comprising silver and the layer comprising silicon nitride.

26. The method of claim 22, wherein said layer comprising silver is located directly on and contacting a layer comprising zinc oxide.

27. The method of claim 22, wherein said coated article has a visible transmission of at least 75%.

28. The method of claim 22, wherein the coated article has a visible transmission of at least 70% and a sheet resistance (R_s) of no greater than 5.5 ohms/square.

29. The method of claim 22, further comprising heat treating the coated article in a manner sufficient for at least one of tempering and heat bending, so that following said heat treating the coated article has a visible transmission of at least 75% and a sheet resistance (R_s) of no greater than 2.5 ohms/square.

30. The method of claim 22, further comprising sputtering a layer comprising zinc oxide on the glass substrate so that the layer comprising silver is located over and directly contacting the layer comprising zinc oxide, and sputtering a layer comprising tin oxide on the substrate over at least the layer comprising silver.

31. The method of claim 22, wherein the layer comprising silicon nitride further includes at least one of aluminum and oxygen.

32. The method of claim 22, wherein the nitrogen-doped Si₃N₄ includes Si₃N₄ and is doped with at least 0.1% nitrogen as a doping amount in at least part of the layer comprising silicon nitride.

33. The method of claim 22, wherein the nitrogen-doped Si₃N₄ includes Si₃N₄ and is doped with from about 0.5 to 20% nitrogen as a doping amount in at least part of the layer comprising silicon nitride.

34. The method of claim 22, wherein the nitrogen-doped Si₃N₄ includes Si₃N₄ and is doped with from about 1 to 20% nitrogen as a doping amount in at least part of the layer comprising silicon nitride.

35. The method of claim 22, wherein the nitrogen-doped Si₃N₄ includes Si₃N₄ and is doped with from about 2 to 20% nitrogen as a doping amount in at least part of the layer comprising silicon nitride.

36. The method of claim 22, wherein the nitrogen-doped Si₃N₄ includes Si₃N₄ and is doped with from about 2 to 10% nitrogen as a doping amount in at least part of the layer comprising silicon nitride.

37. The method of claim 22, wherein the ion beam treating is performed at the same time that a target comprising silicon is being sputtered so that material from the target and ions from the ion beam contribute simultaneously to growing of the layer comprising silicon nitride.

38. The method of claim 22, wherein the layer comprising silicon nitride is formed via sputtering, and the ion beam treating is performed after sputter-deposition of the layer comprising silicon nitride.

39. A method of making a coated article, the method comprising:

providing a glass substrate;

ion beam treating a layer comprising silicon nitride using at least nitrogen ions so that the ion beam treated layer comprising silicon nitride comprises nitrogen-doped Si₃N₄.

40. The method of claim 39, wherein the layer comprising silicon nitride is an overcoat layer which is an uppermost layer of the coated article.

41. The method of claim 39, further comprising forming at least one dielectric layer on the substrate so as to be located between the substrate and a layer comprising silver, and sputtering at least a contact layer on the substrate over at least the layer comprising silver so as to be located between the layer comprising silver and the layer comprising silicon nitride.

42. The method of claim 39, wherein said coated article has a visible transmission of at least 75%.

43. The method of claim 39, wherein the coated article has a visible transmission of at least 70% and a sheet resistance (R_s) of no greater than 5.5 ohms/square.

44. The method of claim 39, further comprising heat treating the coated article in a manner sufficient for at least one of tempering and heat bending, so that following said heat treating the coated article has a visible transmission of at least 75% and a sheet resistance (R_s) of no greater than 2.5 ohms/square.

45. The method of claim 39, wherein the layer comprising silicon nitride further includes aluminum.

46. The method of claim 39, wherein the nitrogen-doped Si₃N₄ includes Si₃N₄ and is doped with at least 0.1% nitrogen as a doping amount in at least part of the layer comprising silicon nitride.

47. The method of claim 39, wherein the nitrogen-doped Si₃N₄ includes Si₃N₄ and is doped with from about 0.5 to 20% nitrogen as a doping amount in at least part of the layer comprising silicon nitride.

48. The method of claim 39, wherein the nitrogen-doped Si₃N₄ includes Si₃N₄ and is doped with from about 1 to 20% nitrogen as a doping amount in at least part of the layer comprising silicon nitride.

49. The method of claim 39, wherein the nitrogen-doped Si₃N₄ includes Si₃N₄ and is doped with at least about 2% nitrogen as a doping amount in at least part of the layer comprising silicon nitride.

50. The method of claim 39, wherein the nitrogen-doped Si₃N₄ includes Si₃N₄ and is doped with at least about 5% nitrogen as a doping amount in at least part of the layer comprising silicon nitride.

51. A method of making a coated article, the method comprising:

providing a glass substrate;

forming an IR reflecting layer on the glass substrate;

sputtering a layer comprising silicon nitride on the substrate over the IR reflecting layer;

ion beam treating the layer comprising silicon nitride using at least oxygen ions so as to form a layer comprising silicon oxynitride which is non-uniformly oxided throughout its thickness.

52. The method of claim 51, wherein the layer comprising silicon oxynitride is oxidation graded.

53. The method of claim 52, wherein the layer comprising silicon oxynitride is less oxidized at a location closer to the IR reflecting layer than at a location further from the IR reflecting layer.

54. The method of claim 51, further comprising sputtering at least one dielectric layer on the substrate so as to be located between the substrate and the IR reflecting layer.

55. The method of claim 51, wherein the layer comprising silicon oxynitride is an overcoat layer which is an uppermost layer of the coated article.

56. A method of making a coated article which includes a coating supported by a glass substrate, the method comprising:

providing the glass substrate;

forming an IR reflecting layer on the glass substrate;

forming at least an outermost layer of the coating on the substrate over the IR reflecting layer by using at least a sputtering target;

ion beam treating the outermost layer of the coating in a manner so as to cause a stress of the outermost layer of the coating to be compressive due to the ion beam treating.

57. The method of claim 56, wherein the ion beam treating causes stress of the outermost layer to change from tensile to compressive.

58. The method of claim 56, wherein the outermost layer of the coating comprises silicon nitride.

59. The method of claim 58, wherein the ion beam treating uses at least nitrogen ions which are at least one of:

(a) directed toward the layer comprising silicon nitride at the same time the layer comprising silicon nitride is being grown by at least sputtering, and (b) directed toward the layer comprising silicon nitride after the layer comprising silicon nitride has been sputter-deposited.

60. A method of making a coated article which includes a coating supported by a glass substrate, the method comprising:

providing the coating so as to include at least one infrared (IR) reflecting layer sandwiched between at least first and second dielectric layers; and

in providing the coating, ion beam treating at least one layer thereof in a manner so as to cause a tensile stress thereof to be reduced by at least 10% due to the ion beam treating.

61. The method of claim 60, wherein the layer which is ion beam treated comprises silicon nitride.

62. The method of claim 60, wherein the ion beam treating causes a tensile stress of the at least one layer to be reduced by at least 20% due to the ion beam treating.

63. The method of claim 60, wherein the ion beam treating causes a tensile stress of the at least one layer to be reduced by at least 50% due to the ion beam treating.

64. A method of making a coated article, the method comprising:

providing a glass substrate;

forming an IR reflecting layer on the glass substrate; and

providing a layer comprising silicon nitride on the glass substrate, wherein the layer comprising silicon nitride is ion beam treated using an energy of at least about 550 eV per N₂⁺ ion.

65. The method of claim 64, wherein the layer comprising silicon nitride is located over the IR reflecting layer, and is an outer layer of a coating provided on the glass substrate.

66. The method of claim 64, wherein the IR reflecting layer comprises silver and is located on and directly contacting a layer comprising zinc oxide.

67. The method of claim 64, wherein said ion beam treating includes using an energy of from about 600 to 1,100 eV per N₂⁺ ion.

68. A coated article including a coating supported by a glass substrate, the coating comprising:

a layer comprising silicon nitride located over at least a layer comprising silver;

wherein the layer comprising silicon nitride comprises nitrogen-doped Si₃N₄.

69. The coated article of claim 68, wherein the layer comprising silicon nitride is an overcoat layer which is an uppermost layer of the coating.

70. The coated article of claim 68, wherein at least one dielectric layer is provided on the glass substrate so as to be located between the substrate and the layer comprising silver, and wherein a contact layer is provided so as to be located between the layer comprising silver and the layer comprising silicon nitride.

71. The coated article of claim 68, wherein said coated article has a visible transmission of at least 75%.

72. The coated article of claim 68, wherein the coated article has a visible transmission of at least 70% and a sheet resistance (R_s) of no greater than 5.5 ohms/square.

73. The coated article of claim 68, wherein the coated article is heat treated in a manner sufficient for at least one of tempering and heat bending, so that following said heat treating the coated article has a visible transmission of at least 75% and a sheet resistance (R_s) of no greater than 2.5 ohms/square.

74. The coated article of claim 68, wherein the layer comprising silicon nitride further includes aluminum.

75. The coated article of claim 68, wherein the nitrogen-doped Si₃N₄ includes Si₃N₄ and is doped with at least 0.1% nitrogen as a doping amount in at least part of the layer comprising silicon nitride.

76. The coated article of claim 68, wherein the nitrogen-doped Si₃N₄ includes Si₃N₄ and is doped with from about 0.5 to 20% nitrogen as a doping amount in at least part of the layer comprising silicon nitride.

77. The coated article of claim 68, wherein the nitrogen-doped Si₃N₄ includes Si₃N₄ and is doped with from about 1 to 20% nitrogen as a doping amount in at least part of the layer comprising silicon nitride.

78. The coated article of claim 68, wherein the nitrogen-doped Si₃N₄ includes Si₃N₄ and is doped with at least about 2% nitrogen as a doping amount in at least part of the layer comprising silicon nitride.

79. The coated article of claim 68, wherein the nitrogen-doped Si₃N₄ includes Si₃N₄ and is doped with at least about 5% nitrogen as a doping amount in at least part of the layer comprising silicon nitride.

80. The coated article of claim 68, wherein the layer comprising silicon nitride is nitrogen graded so that a portion of the layer comprising silicon nitride further from the glass substrate has a higher nitrogen content than does a portion of the layer closer to the glass substrate.

81. A coated article including a coating supported by a glass substrate, the coating comprising:

a layer comprising silicon nitride located over at least a layer comprising silver; and

wherein a portion of the layer comprising silicon nitride further from the glass substrate has a higher nitrogen content than does a portion of the layer comprising silicon nitride closer to the glass substrate.

82. The coated article of claim 81, wherein the layer comprising silicon nitride comprises nitrogen-doped Si₃N₄.

83. The coated article of claim 81, wherein an outermost 20 Å

thick portion of the layer comprising silicon nitride has a higher nitrogen content than an innermost 20 Å

thick portion of the layer comprising silicon nitride.

84. The coated article of claim 81, wherein an outermost 20 Å

thick portion of the layer comprising silicon nitride has at least a 5% higher nitrogen content than an innermost 20 Å

thick portion of the layer comprising silicon nitride.

85. The coated article of claim 81, wherein an outermost 20 Å

thick portion of the layer comprising silicon nitride has at least a 10% higher nitrogen content than an innermost 20 Å

thick portion of the layer comprising silicon nitride.

86. The coated article of claim 81, wherein the coated article has a visible transmission of at least about 70% and a sheet resistance (R_s) of less than or equal to about 6 ohms/square.

88. The coated article of claim 86, wherein an outermost 20 Å

thick portion of the layer comprising silicon nitride has at least a 10% higher nitrogen content than an innermost 20 Å

thick portion of the layer comprising silicon nitride.

87. A coated article including a coating supported by a glass substrate, comprising:

a layer comprising silicon nitride supported by the glass substrate;

wherein a portion of the layer comprising silicon nitride further from the glass substrate has a higher nitrogen content than does a portion of the layer comprising silicon nitride closer to the glass substrate; and

wherein the coated article has a visible transmission of at least about 70% and a sheet resistance (R_s) of less than or equal to about 6 ohms/square.

89. A coated article including a coating supported by a glass substrate, comprising:

an IR reflecting layer supported by the glass substrate;

an overcoat layer provided over at least the IR reflecting layer, wherein the overcoat layer is non-uniform with regard to nitrogen content so that a portion of the overcoat layer further from the glass substrate has a higher nitrogen content than does a portion of the overcoat layer closer to the glass substrate; and

wherein the coated article has a visible transmission of at least about 70% and a sheet resistance (R_s) of less than or equal to about 6 ohms/square.