Oxide semiconductor thin-film transistor

• US 8,304,773 B2
• Filed: 11/27/2008
• Issued: 11/06/2012
• Est. Priority Date: 12/04/2007
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Shimada, Mikio
• Primary Examiner(s): SANDVIK, BENJAMIN P
• Application Number:
  US12/679,667
• Publication Number:
  US 20100200857A1
• Time in Patent Office: 1,440 Days
• Field of Search: None
• US Class Current: 257/59
• CPC Class Codes: H01L 29/78618 characterised by the drain or the source properties, e.g. the doping structure, the composition, the sectional shape or the contact structure silicide contacts, electrodes in general H01L29/458
• CPC Class Codes: H01L 29/7869 having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate

Abstract

A transistor includes a gate electrode, a gate insulating layer, a semiconductor layer including an amorphous oxide, source-drain electrodes, and a protective layer on a substrate. The semiconductor layer includes a first region corresponding to a region in which the source-drain electrodes are formed, and a second region not corresponding to the region in which the source-drain electrodes are formed. At least the first region includes a crystalline component having a composition different from the composition of the amorphous oxide in the second region.

Claims

1. A thin film transistor comprising a gate electrode, a gate insulating layer, a semiconductor layer, source-drain electrodes, and a protective layer,

wherein the semiconductor layer comprises a first region and a second region,

wherein the first region overlaps with the source-drain electrodes,

wherein the second region does not overlap with the source-drain electrodes,

wherein the first region comprises a metal crystal, and the second region comprises an amorphous oxide, and

wherein the metal crystal contains a metal contained in the amorphous oxide.

2. The thin film transistor according to claim 1, wherein the amorphous oxide is an amorphous oxide semiconductor containing at least one of In, Sn, Zn and Ga.

3. A display device using the thin-film transistor according to claim 1.

4. The thin-film transistor according to claim 1, wherein a composition of the first region is different from a composition of the second region.

5. The thin-film transistor according to claim 1, wherein a proportion of a metal per unit volume in the first region is larger than a proportion of the metal per unit volume in the second region.

6. The thin-film transistor according to claim 1, wherein the second region functions as a channel region.

7. The thin-film transistor according to claim 1, wherein the first region is between the gate insulating layer and the source-drain electrodes.

8. The thin-film transistor according to claim 1, wherein the second region is provided over the gate electrode with the gate insulating layer interposed therebetween.

9. The thin-film transistor according to claim 1, wherein the protective layer is provided over the second region and the source-drain electrodes.

10. The thin-film transistor according to claim 1, wherein the metal crystal has an In-excess composition.

11. The thin-film transistor according to claim 1, wherein the metal crystal has a Ga-excess composition.

12. The thin-film transistor according to claim 1, wherein the metal crystal has a Zn-excess composition.