Temperable three layer antireflective coating, coated article including temperable three layer antireflective coating, and/or method of making the same

• US 20110157703A1
• Filed: 09/03/2010
• Published: 06/30/2011
• Est. Priority Date: 09/03/2010
• Status: Active Grant

• Current Assignee: Guardian Glass LLC (KOCH Industries Incorporated)
• Original Assignee: Guardian Industries Corporation (KOCH Industries Incorporated)
• Inventors: Broadway, David M., Golden, Darrell, Patriacca, Paul, Scott, Gregory, Lu, Yiwei, den Boer, Willem
• Granted Patent: US 8,693,097 B2
• Time in Patent Office: Days
• US Class Current: 359/586
• CPC Class Codes: C03C 17/3435 comprising a nitride, oxynitride, boronitride or carbonitride
• CPC Class Codes: C03C 2217/734 comprising an alternation of high and low refractive indexes
• CPC Class Codes: G02B 1/115 Multilayers

Abstract

A coated article includes a temperable antireflection (AR) coating that utilizes medium and low index (index of refraction “n”) layers having compressive residual stress in the AR coating. In certain example embodiments, the coating may include the following layers from the glass substrate outwardly: silicon oxynitride (SiO_xN_y) medium index layer/high index layer/low index layer. In certain example embodiments, depending on the chemical and optical properties of the high index layer and the substrate, the medium and low index layers of the AR coating are selected to cause a net compressive residual stress and thus optimize the overall performance of the antireflection coating when the coated article is tempered and/or heat-treated.

Claims

1. A coated article comprising:

an antireflective coating supported by a major surface of a substrate, the substrate being heat treated together with the antireflective coating,

wherein the antireflective coating comprises, in order moving away from the substrate;

a medium index layer comprising silicon oxynitride and having a index of refraction of from about 1.65 to 2.0 at 380 nm, 550 nm, and 780 nm wavelengths,

a high index layer having an index of refraction of at least about 2.0 at 380 nm, 550 nm, and 780 nm wavelengths, and

a low index layer having an index of refraction of from about 1.4 to 1.6 at 380 nm, 550 nm, and 780 nm wavelengths,

wherein the medium index layer has compressive residual stress after heat treatment.

2. The coated article of claim 1, wherein the substrate is a glass substrate, and wherein the low index layer is an outermost layer of the coating.

3. The coated article of claim 1, wherein each of the high, medium and low index layers are dielectric layers.

4. The coated article of claim 1, wherein the high index layer has an index of refraction of from about 2.3 to 2.5 at 550 nm.

5. The coated article of claim 1, wherein the low index layer has an index of refraction of from about 1.45 to 1.55 at 550 nm.

6. The coated article of claim 4, wherein the high index layer comprises an oxide of titanium.

7. The coated article of claim 6, wherein the low index layer comprises silicon oxide.

8. The coated article of claim 1, wherein the medium index layer comprising silicon oxynitride and has an index of refraction of from about 1.7 to 1.8 at 550 nm.

9. The coated article of claim 1, wherein the high index layer comprises an oxide of titanium and the low index layer comprises silicon oxide.

10. The coated article of claim 1, wherein the medium index layer and the low index layer both have compressive residual stresses following heat treatment.

11. The coated article of claim 1, wherein the high index layer comprises an oxide of titanium, and has a thickness of from about 12 to 22 nm.

12. The coated article of claim 1, wherein the medium index layer comprising silicon oxynitride has a thickness of from about 94 to 115 nm.

13. The coated article of claim 1, wherein the low index layer comprises an oxide of silicon, and has a thickness of from about 89 to 109 nm.

14. The coated article of claim 1, wherein the coated article has a photopic reflection of no greater than about 2%.

15. The coated article of claim 1, wherein the coated article has a photopic reflection of no greater than about 1%.

16. The coated article of claim 1, further comprising a second antireflective coating supported by a second major surface of a substrate, the substrate being heat treated together with the second antireflective coating.

17. The coated article of claim 1, wherein the substrate is a low-iron glass substrate.

18. The coated article of claim 17, wherein the coated article has a visible transmission of at least about 95%.

19. The coated article of claim 17, wherein the high index layer has a tensile residual stress and a thickness of less than 25 nm.

20. A heat treatable coated article, comprising:

an antireflective coating supported by a major surface of a substrate, wherein the antireflective coating comprises, in order moving away from the substrate;

a medium index silicon-inclusive layer having a index of refraction of 1.8 or less at 550 nm and 780 nm wavelengths and 2.0 or less at 380 nm,

a high index layer having an index of refraction higher than that of the medium index layer at 380 nm, 550 nm, and 780 nm wavelengths, wherein the high index layer has a thickness no greater than 20 nm, and

a low index layer having an index of refraction lower than that of the medium index layer at 380 nm, 550 nm, and 780 nm wavelengths,

wherein the medium index layer and the low index layer have compressive residual stress, the high index layer has tensile residual stress, and the antireflective coating has a net compressive residual stress.

21. A method of making a coated article with a three-layered antireflection coating, the method comprising:

disposing a silicon-inclusive medium index layer, directly or indirectly, on a glass substrate;

disposing a high index layer over and contacting the medium index layer;

disposing a low index layer over and contacting the high index layer; and

heat-treating the glass substrate with the antireflective coating thereon, and

wherein the coated article has a net compressive residual stress.

22. The method of claim 21, wherein:

the medium index layer comprises silicon oxynitride and has an index of refraction from about 1.8 to 2.0 at 380 nm, from about 1.7 to 1.8 at 550 nm, and from about 1.65 to 1.8 at 780 nm;

the high index layer comprises an oxide of titanium and has an index of refraction of from about 2.7 to 2.9 at 380 nm, from about 2.3 to 2.5 at 550 nm, and from about 2.2 to 2.4 at 780 nm; and

the low index layer comprises an oxide of silicon, and has an index of refraction of from about 1.45 to 1.55 at 380 nm, 550 nm, and 780 nm.

23. The method of claim 21, wherein the high index layer comprises an oxide of titanium and has a thickness of less than about 25 nm.

24. The method of claim 21, wherein the high index layer comprises an oxide of titanium and has a thickness of less than about 22 nm.

25. A method of making a heat treatable coated article with a three-layered antireflection coating, the method comprising:

disposing a silicon-inclusive medium index layer, directly or indirectly, on a low-iron glass substrate, the medium index layer having a index of refraction of from about 1.65 to 2.0 at 380 nm, 550 nm, and 780 nm wavelengths;

disposing a high index layer over and contacting the medium index layer, the high index layer being no more than about 22 nm thick;

disposing a low index layer over and contacting the high index layer; and

wherein the coated article has a net compressive residual stress.

26. The method of claim 25, further comprising heat-treating the glass substrate with the antireflective coating thereon.