Displays with silicon and semiconducting oxide thin-film transistors

• US 9,818,765 B2
• Filed: 04/10/2014
• Issued: 11/14/2017
• Est. Priority Date: 08/26/2013
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Osawa, Hiroshi, Kim, Kyung-Wook, Hung, Ming-Chin, Chang, Shih Chang, Chen, Yu-Cheng
• Primary Examiner(s): Chen, Wen-Ying P
• Application Number:
  US14/249,716
• Publication Number:
  US 20150055051A1
• Time in Patent Office: 1,314 Days
• CPC Class Codes: G02F 1/13452 Conductors connecting driver circuitry and terminals of panels
• CPC Class Codes: G02F 1/13454 Drivers integrated on the active matrix substrate G02F1/136277 takes precedence
• CPC Class Codes: G02F 1/13624 having more than one switching element per pixel
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence
• CPC Class Codes: G02F 1/13685 Top gates
• CPC Class Codes: G02F 2202/104 poly-Si
• CPC Class Codes: H01L 27/1222 with a particular composition, shape or crystalline structure of the active layer
• CPC Class Codes: H01L 27/1225 with semiconductor materials not belonging to the group IV of the periodic table, e.g. InGaZnO
• CPC Class Codes: H01L 27/1251 comprising TFTs having a different architecture, e.g. top- and bottom gate TFTs
• CPC Class Codes: H01L 27/1255 integrated with passive devices, e.g. auxiliary capacitors
• CPC Class Codes: H01L 29/7869 having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate
• CPC Class Codes: H10K 59/1213 the pixel elements being TFTs
• CPC Class Codes: H10K 59/126 Shielding, e.g. light-blocking means over the TFTs

Abstract

An electronic device may include a display having an array of display pixels on a substrate. The display pixels may be organic light-emitting diode display pixels or display pixels in a liquid crystal display. In an organic light-emitting diode display, hybrid thin-film transistor structures may be formed that include semiconducting oxide thin-film transistors, silicon thin-film transistors, and capacitor structures. The capacitor structures may overlap the semiconducting oxide thin-film transistors. Organic light-emitting diode display pixels may have combinations of oxide and silicon transistors. In a liquid crystal display, display driver circuitry may include silicon thin-film transistor circuitry and display pixels may be based on oxide thin-film transistors. A single layer or two different layers of gate metal may be used in forming silicon transistor gates and oxide transistor gates. A silicon transistor may have a gate that overlaps a floating gate structure.

Claims

1. A display, comprising:

a substrate;

an array of display pixels on the substrate;

display driver circuitry on the substrate, wherein the display driver circuitry and the display pixels include thin-film transistors, and wherein the thin-film transistors include at least one top gate semiconducting oxide transistor and at least one silicon transistor;

a layer of gate metal that is patterned to form a first gate for the silicon transistor and a second gate for the top gate semiconducting oxide transistor; and

source-drain electrodes for the top gate semiconducting oxide transistor, wherein the source-drain electrodes for the top gate semiconducting oxide transistor do not overlap the second gate.

2. The display defined in claim 1 further comprising a layer of polysilicon on the substrate that forms a silicon channel for the silicon transistor, wherein the first gate is above the layer of polysilicon.

3. The display defined in claim 2 further comprising a semiconducting oxide layer on the substrate that forms a semiconducting oxide channel for the top gate semiconducting oxide transistor, wherein the second gate is above the semiconducting oxide layer.

4. The display defined in claim 3 further comprising a gate insulator layer.

5. The display defined in claim 4 wherein a first portion of the gate insulator layer is interposed between the first gate and the polysilicon layer.

6. The display defined in claim 5 wherein a second portion of the gate insulator layer is interposed between the second gate and the semiconducting oxide layer.

7. The display defined in claim 6 further comprising source-drain electrodes for the silicon transistor, wherein the source-drain electrodes for the silicon transistor and the source-drain electrodes for the top gate semiconducting oxide transistor are formed from a patterned layer of metal.

8. The display defined in claim 7 further comprising

a silicon oxide layer interposed between the layer of metal from which the source-drain electrodes are formed and the first and second gates.

9. The display defined in claim 8 further comprising:

a display pixel electrode; and

an organic layer interposed between the display pixel electrode and the source-drain electrodes.

10. The display defined in claim 8 further comprising:

a display pixel electrode;

a first organic layer interposed between the display pixel electrode and the source-drain electrodes; and

a second organic layer interposed between the source-drain electrodes and the silicon oxide layer.

11. The display defined in claim 6 further comprising a light shield under the semiconducting oxide layer.

12. A display, comprising:

a substrate;

an array of display pixels on the substrate;

display driver circuitry on the substrate, wherein the display driver circuitry and the display pixels include thin-film transistors and wherein the thin-film transistors include at least one top gate semiconducting oxide transistor and at least one silicon transistor;

a layer of gate metal that is patterned to form a first gate for the silicon transistor and a second gate for the top gate semiconducting oxide transistor;

a layer of polysilicon on the substrate that forms a silicon channel for the silicon transistor, wherein the first gate is above the layer of polysilicon;

a semiconducting oxide layer on the substrate that forms a semiconducting oxide channel for the top gate semiconducting oxide transistor, wherein the second gate is above the semiconducting oxide layer;

a gate insulator layer, wherein a first portion of the gate insulator layer is interposed between the first gate and the polysilicon layer and a second portion of the gate insulator layer is interposed between the second gate and the semiconducting oxide layer;

source-drain electrodes for the thin-film transistors, wherein the source-drain electrodes are formed from a patterned layer of metal;

a silicon oxide layer interposed between the layer of metal from which the source-drain electrodes are formed and the first and second gates; and

a silicon nitride layer interposed between the layer of metal from which the source-drain electrodes are formed and the first and second gates.

13. A display, comprising:

a light-emitting diode;

a top gate semiconducting oxide thin-film transistor coupled to the light-emitting diode;

a silicon thin-film transistor;

a layer of gate metal that is patterned to form a first gate for the silicon thin-film transistor and a second gate for the top gate semiconducting oxide thin-film transistor;

a layer of polysilicon that forms a silicon channel for the silicon thin-film transistor, wherein the first gate is above the layer of polysilicon;

a semiconducting oxide layer that forms a semiconducting oxide channel for the top gate semiconducting oxide thin-film transistor, wherein the second gate is above the semiconducting oxide layer;

source-drain electrodes for the silicon thin-film transistor and the top gate semiconducting oxide thin-film transistor, wherein the source-drain electrodes are formed from a patterned layer of metal;

a gate insulator having a first portion interposed between the first gate and the layer of polysilicon and having a second portion interposed between the second gate and the semiconducting oxide layer; and

a dielectric layer formed separately from the gate insulator, wherein the dielectric layer is interposed between the layer of metal from which the source-drain electrodes are formed and the first and second gates.

14. The display defined in claim 13 wherein the light-emitting diode comprises a cathode, an anode, and an organic emissive layer between the anode and the cathode, and wherein the anode is coupled to the source-drain electrodes for the top gate semiconducting oxide thin-film transistor.

15. The display defined in claim 13 further comprising an additional dielectric layer formed separately from the dielectric layer, wherein the additional dielectric layer is interposed between the layer of metal from which the source-drain electrodes are formed and the first and second gates.

16. A display, comprising:

a light-emitting diode, wherein the light-emitting diode comprises a cathode, an anode, and an organic emissive layer between the anode and the cathode;

a silicon thin-film transistor;

a semiconducting oxide thin-film transistor having source-drain electrodes, having a semiconducting oxide layer coupled to the source-drain electrodes, and having a gate;

a light-shielding layer that overlaps at least part of the silicon thin-film transistor and at least part of the semiconducting oxide thin-film transistor, wherein the organic emissive layer overlaps the light-shielding layer; and

a gate insulator layer having a first portion that serves as a gate insulator for the silicon thin-film transistor and having a second portion that serves as a gate insulator for the semiconducting oxide thin-film transistor.

17. The display defined in claim 16 further comprising a source-drain electrode in the semiconducting oxide thin-film transistor that is coupled to the anode.