Encapsulation Layers with Improved Reliability

• US 20150333293A1
• Filed: 05/06/2015
• Published: 11/19/2015
• Est. Priority Date: 05/13/2014
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Poon, Stephen S., Yang, Chih Jen, Boesch, Damien S., Visweswaran, Bhadrinarayana L.
• Granted Patent: US 9,818,976 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H10K 50/844 Encapsulations
• CPC Class Codes: H10K 59/00 Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
• CPC Class Codes: H10K 59/8731 multilayered coatings having a repetitive structure, e.g. having multiple organic-inorganic bilayers
• CPC Class Codes: H10K 71/00 Manufacture or treatment specially adapted for the organic devices covered by this subclass

Abstract

An electronic device may include a display having an array of organic light-emitting diodes formed on a substrate. An encapsulation layer may be formed over the array of organic light-emitting diodes to protect the organic light-emitting diodes from moisture and other contaminants. The encapsulation layer may include a transparent sheet of material interposed between upper and lower inorganic films. The reliability of the encapsulation layer is increased by dividing one or both of the inorganic films into multiple sub-layers. The sub-layers may have different densities and may be deposited in sequential steps. Additional moisture protection may be provided by forming a conformal thin-film coating over the organic light-emitting diodes. The conformal thin-film coating may be an aluminum oxide layer that is formed using atomic layer deposition techniques.

Claims

1. An encapsulation layer for encapsulating organic light-emitting diodes, comprising:

a first inorganic layer having multiple sub-layers;

a second inorganic layer; and

a transparent dielectric layer interposed between the first and second inorganic layers.

2. The encapsulation layer defined in claim 1 wherein the first and second inorganic layers comprise silicon nitride.

3. The encapsulation layer defined in claim 2 wherein the sub-layers have different respective densities.

4. The encapsulation layer defined in claim 2 wherein the sub-layers have different respective indices of refraction.

5. The encapsulation layer defined in claim 1 further comprising a conformal thin-film coating formed on a surface of the organic light-emitting diodes.

6. The encapsulation layer defined in claim 5 wherein the conformal thin-film coating comprises aluminum oxide.

7. The encapsulation layer defined in claim 1 further comprising a conformal thin-film coating interposed between the second inorganic layer and the transparent dielectric layer.

8. The encapsulation layer defined in claim 7 wherein the conformal thin-film coating comprises aluminum oxide.

9. The encapsulation layer defined in claim 1 wherein the transparent dielectric layer comprises a layer of polymer.

10. The encapsulation layer defined in claim 1 wherein the transparent dielectric layer comprises a layer of glass.

11. A method for forming an encapsulation layer for encapsulating organic light-emitting diodes, comprising:

with deposition equipment, depositing a first inorganic layer over the organic light-emitting diodes;

depositing a transparent dielectric layer over the first inorganic layer; and

with the deposition equipment, depositing a second inorganic layer over the transparent dielectric layer, where depositing the second inorganic layer comprises depositing a first sub-layer of inorganic material over the transparent dielectric layer and depositing a second sub-layer of inorganic material over the first sub-layer of inorganic material.

12. The method defined in claim 11 further comprising:

with atomic layer deposition equipment, forming a conformal film over the organic light-emitting diodes.

13. The method defined in claim 11 wherein the deposition equipment comprises plasma-enhanced chemical vapor deposition equipment.

14. The method defined in claim 11 wherein a refractive index of the first sub-layer of inorganic material is different than a refractive index of the second sub-layer of inorganic material.

15. The method defined in claim 11 wherein the first and second sub-layers of inorganic material comprise silicon nitride and wherein depositing the second sub-layer of inorganic material comprises depositing the second sub-layer of inorganic material after depositing the first sub-layer of inorganic material.

16. A display, comprising:

a substrate;

an array of organic light-emitting diodes formed on the substrate; and

an encapsulation layer formed over the organic light-emitting diodes, wherein the encapsulation layer comprises a transparent sheet of material interposed between first and second inorganic films, wherein at least the first inorganic film comprises first and second sub-layers.

17. The display defined in claim 16 wherein the first and second sub-layers have different indices of refraction.

18. The display defined in claim 16 wherein the transparent sheet of material comprises a transparent polymer sheet and wherein the first and second inorganic films comprise silicon nitride.

19. The display defined in claim 16 further comprising a conformal thin-film interposed between the transparent sheet of material and the organic light-emitting diodes.

20. The display defined in claim 19 wherein the conformal thin-film comprises aluminum oxide.