Flexible Display With Bent Edge Regions

• US 20160079281A1
• Filed: 11/30/2015
• Published: 03/17/2016
• Est. Priority Date: 04/09/2013
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Park, Young Bae, Chang, Shih Chang, GUPTA, VASUDHA
• Granted Patent: US 9,640,561 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H01L 27/1218 with a particular composition or structure of the substrate
• CPC Class Codes: H01L 27/124 with a particular composition, shape or layout of the wiring layers specially adapted to the circuit arrangement, e.g. scanning lines in LCD pixel circuits wiring structures per se H01L23/52
• CPC Class Codes: H01L 27/1259 Multistep manufacturing methods
• CPC Class Codes: H10K 2102/311 Flexible OLED
• CPC Class Codes: H10K 59/131 Interconnections, e.g. wiring lines or terminals
• CPC Class Codes: H10K 77/111 Flexible substrates
• CPC Class Codes: Y02E 10/549 Organic PV cells

Abstract

An electronic device may have a flexible display with portions that are bent along a bend axis. The display may have display circuitry such as an array of display pixels in an active area. Contact pads may be formed in an inactive area of the display. Signal lines may couple the display pixels to the contact pads. The signal lines may overlap the bend axis in the inactive area of the display. During fabrication, an etch stop may be formed on the display that overlaps the bend axis. The etch stop may prevent over etching of dielectric such as a buffer layer on a polymer flexible display substrate. A layer of polymer that serves as a neutral stress plane adjustment layer may be formed over the signal lines in the inactive area of the display. Upon bending, the neutral stress plane adjustment layer helps prevent stress in the signal lines.

Claims

1. A display, comprising:

a display substrate;

metal traces on the display substrate that overlap a bend axis along which the display substrate is bent; and

a layer of polymer overlapping the metal traces along the bend axis.

2. The display defined in claim 1 wherein the display has an active area with an array of display pixels and an inactive area, the display further comprising:

a first buffer layer on the display substrate;

a metal structure on the first buffer layer in the active area;

a second buffer layer that overlaps the metal structure; and

polysilicon structures on the second buffer layer.

3. The display defined in claim 2 wherein the metal structure is formed as part of a layer containing an etch stop structure in the inactive area, the display further comprising:

gate insulator on the polysilicon structures and the second buffer layer; and

interlayer dielectric on the gate insulator.

4. The display defined in claim 3, wherein the interlayer dielectric is formed on the gate insulator in the active area and in the inactive area.

5. The display defined in claim 4, further comprising a bond pad on the interlayer dielectric in the inactive area, wherein the bond pad is configured to couple the metal traces to a display driver integrated circuit.

6. The display defined in claim 5, further comprising:

a first metal layer that forms transistor gate structures on the gate insulator in the active area;

a second metal layer that forms the metal traces in the inactive area and that forms source and drain contacts for the polysilicon structures in the active area; and

a third metal layer that forms the bond pad in the inactive area and that is coupled to the source and drain contacts in the active area.

7. The display defined in claim 5, wherein a portion of the metal traces are formed directly on the first buffer layer along the bend axis in the inactive area.

8. The display defined in claim 7, wherein the layer of polymer overlaps the portion of the metal traces formed directly on the first buffer layer in the inactive area.

9. The display defined in claim 1, wherein the polymer layer is a neutral stress plane adjustment layer that shifts the neutral stress plane of the display into alignment with the metal traces.

10. A display having an active area and an inactive area, the display comprising:

a flexible substrate;

a buffer layer on the flexible substrate in the active and inactive areas;

polysilicon transistor structures on the buffer layer in the active area;

gate insulator on the buffer layer and the polysilicon transistor structures in the active area;

a first metal layer that forms transistor gates for the polysilicon transistor structures in the active area, wherein the first metal layer is formed on the gate insulator;

interlayer dielectric on the gate insulator and the first metal layer in the active area; and

a second metal layer that forms signal lines in the inactive area and that forms source and drain contacts for the polysilicon transistor structures in the active area.

11. The display defined in claim 10, wherein the second metal layer is formed on the interlayer dielectric in the active area and is formed directly on the buffer layer in the inactive area.

12. The display defined in claim 11, further comprising:

a third metal layer that forms a contact pad in the inactive area and that is coupled to the source and drain contacts in the active area.

13. The display defined in claim 12, wherein the contact pad is configured to couple a display driver integrated circuit to the metal traces.

14. The display defined in claim 13, further comprising:

a passivation layer on the second metal layer, wherein the passivation layer is absent where the contact pad is coupled to the metal traces in the inactive area and where the third metal layer is coupled to the source and drain terminals in the active area.

15. The display defined in claim 11, wherein the second metal layer is formed directly on the buffer layer in the inactive area over a bend axis of the display.

16. A flexible display having an active area and an inactive area, the flexible display comprising:

a buffer layer in the active area and the inactive area;

an interlayer dielectric layer over the buffer layer; and

a metal layer that is formed directly on the interlayer dielectric layer in the active area and that is formed directly on the buffer layer in the inactive area.

17. The flexible display defined in claim 16, wherein the metal layer is formed directly on the buffer layer over a bend axis of the display in the inactive area.

18. The flexible display defined in claim 17, wherein a portion of the interlayer dielectric layer is formed in the inactive area, and wherein a portion of the metal layer is formed directly on the portion of the interlayer dielectric layer that is formed in the inactive area.

19. The flexible display defined in claim 18, wherein the bend axis is between the interlayer dielectric in the active area and the portion of the interlayer dielectric layer in the inactive area.

20. The flexible display defined in claim 19, further comprising:

a polymer layer formed over the bend axis between the interlayer dielectric in the active area and the portion of the interlayer dielectric layer in the inactive area.