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US-RE50892-E1 - Display apparatus

Abstract

A display apparatus includes a substrate having a first substrate, a second substrate, and an inorganic insulating layer between the first substrate and the second substrate. A first buffer layer is on the substrate, wherein the first buffer layer includes n+1 layers, and ‘n’ is 0 or an even number. A first thin film transistor, a second thin film transistor, and a storage capacitor are each on the first buffer layer. The first thin film transistor includes a first active layer formed of a low temperature poly silicon material. The second thin film transistor includes a second active layer formed of an oxide semiconductor material. The storage capacitor includes a first capacitor electrode and a second capacitor electrode.

Inventors

  • JinChae JEON
  • Soyoung Noh
  • Uijin Chung
  • Eunsung KIM
  • Hyunsoo Shin
  • Wonkyung KIM
  • Jeihyun LEE

Assignees

  • LG DISPLAY CO., LTD.

Dates

Publication Date
20260512
Application Date
20230707
Priority Date
20181107

Claims (20)

  1. 1 . A display apparatus, comprising: a display substrate including: a first substrate; a second substrate; and an inorganic insulating layer between the first substrate and the second substrate; a first buffer layer on the display substrate, the first buffer layer including n+1 layers, ‘n’ being 0 or an even number; and a first thin film transistor, a second thin film transistor, and a storage capacitor, each on the first buffer layer, wherein the first substrate and the second substrate are formed of a plastic, wherein the first thin film transistor includes: a first active layer formed of a low temperature poly silicon material, a first gate electrode overlapping the first active layer, with a first gate insulating layer therebetween, and a first source electrode and a first drain electrode, which are electrically connected to the first active layer, wherein the second thin film transistor includes: a second active layer formed of an oxide semiconductor, a second gate electrode overlapping the second active layer, with a second gate insulating layer therebetween, and a second source electrode and a second drain electrode, which are electrically connected to the second active layer, wherein the storage capacitor includes a first capacitor electrode on a same layer as the first gate electrode and a second capacitor electrode overlapping the first capacitor electrode, with a first interlayer insulating layer therebetween, wherein at least one of the first capacitor electrode and the second capacitor electrode is disposed laterally between the first gate electrode and the second gate electrode in a cross-sectional view, and wherein the first capacitor electrode and the second capacitor electrode are disposed below a layer on which the second active layer is disposed.
  2. 2 . The display apparatus of claim 1 , further comprising a hydrogen blocking layer that is an extension of one or both of the first and second capacitor electrodes, and overlaps the second active layer.
  3. 3 . The display apparatus according to claim 1 , wherein the inorganic insulating layer is formed of a silicon oxide (SiOx) or silicon nitride (SiNx) material.
  4. 4 . The display apparatus according to claim 1 , wherein: ‘n’ is 0; and the first buffer layer is a single layer formed of a silicon oxide (SiOx) or a silicon nitride (SiNx) material.
  5. 5 . The display apparatus according to claim 1 , wherein: ‘n’ is equal to or larger than 2; and the first buffer layer is a multi-layer in which a silicon oxide (SiOx) layer and a silicon nitride (SiNx) layer are alternately formed.
  6. 6 . The display apparatus according to claim 5 , wherein the n+1 layers of the first buffer layer include: a lower layer that contacts the display substrate, and is formed of the silicon oxide (SiOx) material; an upper layer that contacts the first active layer, and is formed of the silicon oxide (SiOx) material; and an intermediate layer between the upper layer and the lower layer.
  7. 7 . The display apparatus according to claim 6 , wherein a thickness of the upper layer is larger than a thickness of the intermediate layer and a thickness of the lower layer.
  8. 8 . The display apparatus according to claim 7 , wherein the thickness of the intermediate layer is equal to the thickness of the lower layer.
  9. 9 . A display apparatus, comprising: a substrate including a layer formed of a plastic; a first buffer layer on the substrate; a first thin film transistor on the substrate and including: a first active layer formed of a low temperature poly silicon material; a first gate electrode overlapping the first active layer, with a first gate insulating layer therebetween; and a first source electrode and a first drain electrode, which are electrically connected to the first active layer; a second thin film transistor on the substrate and including: a second active layer formed of an oxide semiconductor; a second gate electrode overlapping the second active layer, with a second gate insulating layer therebetween; and a second source electrode and a second drain electrode, which are electrically connected to the second active layer; a storage capacitor including a first capacitor electrode on a same layer as the first gate electrode and a second capacitor electrode overlapping the first capacitor electrode, with a first interlayer insulating layer therebetween; and a first hydrogen blocking layer that is an extension of the second capacitor electrode, which overlaps the second active layer a second interlayer insulating layer over the first active layer and the second active layer and over the first interlayer insulating layer, wherein each of the first source electrode, the first drain electrode, the second source electrode, and the second drain electrode directly contacts an upper surface of the second interlayer insulating layer, wherein the first buffer layer include: a lower layer that contacts the substrate and is formed of a silicon oxide (SiOx) material; an upper layer that contacts the first active layer and is formed of the silicon oxide (SiOx) material; and an intermediate layer between the upper layer and the lower layer, and wherein a thickness of the upper layer is larger than a thickness of the intermediate layer and a thickness of the lower layer.
  10. 10 . The display apparatus according to claim 9 26 , further comprisingwherein: the substrate including includes: a first substrate; a second substrate; and an inorganic insulating layer between the first substrate and the second substrate, and whereinat least one of the first substrate and the second substrate are formedincludes a plastic material.
  11. 11 . The display apparatus according to claim 10 26 , further comprising: a second buffer layer between the first hydrogen blocking layer and the second active layer, and having a plurality of layers including a silicon oxide (SiOx) layer and a silicon nitride (SiNx) layer, wherein the second buffer layer includes the silicon oxide (SiOx) layer as an uppermost layer, which contacts the second active layer, and at least one silicon nitride (SiNx) layer between the uppermost layer and the first hydrogen blocking layer.
  12. 12 . The display apparatus according to claim 10 26 , further comprising a second hydrogen blocking layer that is an extension of the other of the first capacitor electrode and the second capacitor electrode, whichwherein the second hydrogen blocking layer overlaps the second active layer and the first hydrogen blocking layer.
  13. 13 . The display apparatus according to claim 11 , wherein: the second buffer layer includes: a second upper buffer layer; and a second lower buffer layer; the second upper buffer layer is the silicon oxide (SiOx) layer; and the second lower buffer layer is the silicon nitride (SiNx) layer.
  14. 14 . The display apparatus according to claim 13 , wherein the second upper buffer layer is a silicon dioxide (SiO 2 ) layer.
  15. 15 . The display apparatus according to claim 11 , wherein: the first active layer of the first thin film transistor is on the first buffer layer; the first gate insulating layer is on the first active layer and the first buffer layer; the first gate electrode of the first thin film transistor and the first capacitor electrode of the storage capacitor are on the first gate insulating layer; the first interlayer insulating layer is on the first gate electrode and the first capacitor electrode; the second capacitor electrode of the storage capacitor overlapping the first capacitor electrode and the first hydrogen blocking layer overlapping the second active layer are on the first interlayer insulating layer; the second buffer layer is on the second capacitor electrode, the first hydrogen blocking layer, and the first interlayer insulating layer; the second active layer of the second thin film transistor is on the second buffer layer; the second gate insulating layer is on the second active layer; the second gate electrode of the second thin film transistor is on the second gate insulating layer; and the second interlayer insulating layer is on the second gate electrode, the second active layer, and the second buffer layer; and the first source electrode and the first drain electrode of the first thin film transistor and the second source electrode and the second drain electrode of the second thin film transistor are on the second interlayer insulating layer.
  16. 16 . The display apparatus according to claim 15 9 , wherein the second source electrode and the second drain electrode are electrically connected to the second active layer through a contact hole ofrespective contact holes in the second interlayer insulating layer.
  17. 17 . The display apparatus according to claim 15 , wherein the first source electrode and the first drain electrode are electrically connected to the first active layer through contact holes of the second interlayer insulating layer, the second buffer layer, the first interlayer insulating layer, and the first gate insulating layer.
  18. 18 . The display apparatus according to claim 15 , further comprising: a connection electrode on the second interlayer insulating layer, and electrically connecting the second capacitor electrode of the storage capacitor and the second drain electrode of the second thin film transistor to each other, wherein the connection electrode is connected to the second drain electrode to be integrally formed.
  19. 19 . The display apparatus according to claim 18 , wherein the connection electrode is electrically connected to the second capacitor electrode through the contact holes of the second interlayer insulating layer and the second buffer layer.
  20. 20 . The display apparatus according to claim 15 , further comprising: a connection electrode on the second interlayer insulating layer, and electrically connecting the second capacitor electrode of the storage capacitor and the second drain electrode of the second thin film transistor to each other, wherein the connection electrode includes: a second connection electrode integrally connected to the second drain electrode, and a first connection electrode, which connects the second connection electrode and the second capacitor electrode.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a reissue of U.S. patent application Ser. No. 16/575,917, filed Sep. 19, 2019, now U.S Pat. No. 11,063,068, issued Jul. 13, 2021, which claims the priority of Korean Patent Application No. 10-2018-0136203 filed on Nov. 7, 2018, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. BACKGROUND Technical Field The present disclosure relates to a display apparatus, and more particularly, to a display apparatus in which a plurality of thin film transistors is formed with different semiconductors. Description of the Related Art As information technology has developed, a display apparatus has been developed that can represent information contained in an electrical information signals in the form of visual images. Various types of display apparatuses have been developed, some of which have excellent performance characteristics such as thinness, light weight, and/or low power consumption. Examples of display apparatuses include a liquid crystal display apparatus (LCD) and an electroluminescence display apparatus, such as an organic light emitting display apparatus (OLED) or a quantum-dot light emitting display apparatus (QLED). The electroluminescence display apparatus may be a next-generation display apparatus having a self-emitting characteristic, and may have excellent characteristics in terms of viewing angle, contrast, response speed, and power consumption, as compared with a liquid crystal display apparatus. An electroluminescence display apparatus may include a display area for displaying images and a non-display area disposed to be adjacent to the display area. A pixel area, which may be disposed in the display area, may include a pixel circuit and a light emitting element. In the pixel circuit, a plurality of thin film transistors may be disposed to drive the light emitting elements. Thin film transistors may be classified depending on a material used for a semiconductor layer. Among them, a low temperature poly silicon (LTPS) thin film transistor and an oxide semiconductor thin film transistor are most widely used. A technology for an electroluminescence display apparatus in which an LTPS thin film transistor and an oxide semiconductor thin film transistor are formed on the same substrate is actively being developed. SUMMARY Accordingly, embodiments of the present disclosure are directed to a display apparatus that substantially obviates one or more problems due to limitations and disadvantages of the related art. The inventors of the present disclosure recognized that in the manufacturing method of a display apparatus, when the plurality of thin film transistors is formed with different semiconductors, operation characteristics of the pixels can be improved. Therefore, the inventors of the present disclosure invented a display apparatus in which semiconductors of the plurality of thin film transistors may be formed on different layers to form the plurality of thin film transistors with different semiconductors. Also, damage to the semiconductor elements may be reduced. Therefore, an object of the present disclosure is to provide a thin film transistor and a display apparatus which may reduce the damage to semiconductor elements during the manufacturing of the display apparatus caused by forming a plurality of thin film transistors with different semiconductor materials. Additional advantages, objects, and features of the disclosure will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the disclosure. The objectives and other advantages of the disclosure may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. According to an aspect of the present disclosure, a display apparatus includes a substrate including a first substrate, a second substrate, and an inorganic insulating layer between the first substrate and the second substrate; a first buffer layer on the substrate, wherein the first buffer layer includes n+1 layers, and ‘n’ is 0 or an even number; and a first thin film transistor, a second thin film transistor, and a storage capacitor each on the first buffer layer, wherein the first thin film transistor includes a first active layer formed of a low temperature poly silicon material, wherein the second thin film transistor includes a second active layer formed of an oxide semiconductor material, and wherein the storage capacitor includes a first capacitor electrode and a second capacitor electrode. According to another aspect of the present disclosure, a display apparatus includes a substrate; a first buffer layer on the substrate; a first thin film transistor including: a first active layer formed of a low temperature poly silicon mater