Oxide thin film transistor and method of fabricating the same

• US 9,941,410 B2
• Filed: 09/13/2013
• Issued: 04/10/2018
• Est. Priority Date: 05/14/2013
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: Bae, JongUk
• Primary Examiner(s): Nicely, Joseph C
• Assistant Examiner(s): IVANOV, PAVEL G
• Application Number:
  US14/026,769
• Publication Number:
  US 20140339537A1
• Time in Patent Office: 1,670 Days
• Field of Search: 257 43, 438104
• CPC Class Codes: H01L 29/66969 of devices having semiconductor bodies not comprising group 14 or group 13/15 materials comprising selenium or tellurium in uncombined form other than as impurities in semiconductor bodies of other materials, comprising cuprous oxide or cuprous iodide H01L21/02365
• CPC Class Codes: H01L 29/78606 with supplementary region or layer in the thin film or in the insulated bulk substrate supporting it for controlling or increasing the safety of the device H01L29/78642, H01L29/78645 take precedence
• CPC Class Codes: H01L 29/78636 with supplementary region or layer for improving the flatness of the device
• CPC Class Codes: H01L 29/78693 the semiconducting oxide being amorphous

Abstract

The present disclosure relates to an oxide thin film transistor and a fabricating method thereof. In the oxide thin film transistor, which uses amorphous zinc oxide (ZnO) semiconductor as an active layer, damage to the oxide semiconductor due to dry etching may be minimized by forming source and drain electrodes in a multilayered structure having at least two layers, and improving stability and reliability of a device by employing a dual passivation layer structure, which includes a lower layer for overcoming an oxygen deficiency and an upper layer to minimize effects of an external environment on the multilayered source and drain electrodes.

Claims

1. A thin film transistor, comprising:

a gate electrode on a substrate;

a gate insulating layer on the gate electrode;

an active layer on the gate insulating layer, the active layer made of an oxide semiconductor;

a lower conductive layer on the active layer,

wherein the lower conductive layer comprises a source electrode, a drain electrode, and wherein first and second portions of the lower conductive layer are oxidized and converted to first and second portions of an in-situ protection layer, so that the first portion of the in-situ protection layer is directly on a back-channel region of the active layer, and the second portion of the in-situ protection layer is at a side of the source electrode or the drain electrode and is directly on and contacting the gate insulating layer;

an upper conductive layer directly on the lower conductive layer; and

a lower passivation layer directly on the in-situ protection layer and the upper conductive layer.

2. The thin film transistor of claim 1, wherein the lower conductive layer covers a side portion of the active layer.

3. The thin film transistor of claim 1, wherein the in-situ protection layer includes TiOx (where x=2±

∈

, where ∈

is sufficiently small to maintain semiconductor conductivity in TiOx) and the lower conductive layer includes Ti.

7. The thin film transistor of claim 1, further comprising an upper passivation layer on the lower passivation layer.

8. The thin film transistor of claim 1, wherein the lower passivation layer contains oxygen equal to or larger than 1E+20 atoms/cm³, and hydrogen equal to or smaller than 1E+20 atoms/cm³ for curing oxygen deficiency at a back channel region of the active layer.

9. The thin film transistor of claim 1, wherein the lower passivation layer is a porous metal oxide insulating layer.

4. A method of manufacturing a thin film transistor comprising:

forming a gate electrode on a substrate;

forming a gate insulating layer on the gate electrode;

forming an active layer on the gate insulating layer, the active layer made of an oxide semiconductor;

forming a lower conductive layer on the active layer,

wherein the lower conductive layer comprises a source electrode, a drain electrode, a first portion, and a second portion;

oxidizing the first and second portions of the lower conductive layer to convert first and second portions of an in-situ protection layer, so that the first portion of the in-situ protection layer is formed directly on a back-channel region of the active layer, and the second portion of the in-situ protection layer is formed at a side of the source electrode or the drain electrode and is directly formed on and contacting the gate insulating layer;

forming an upper conductive layer directly on the lower conductive layer; and

forming a lower passivation layer directly on the in-situ protection layer and the upper conductive layer.

5. The method of claim 4, further comprising forming an upper passivation layer on the lower passivation layer.

6. The method of claim 4, wherein the lower passivation layer is formed of a porous metal oxide insulating layer.