THIN-FILM TRANSISTOR AND PROCESS FOR ITS FABRICATION

• US 20100059751A1
• Filed: 04/16/2008
• Published: 03/11/2010
• Est. Priority Date: 04/27/2007
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Sano, Masafumi, Takahashi, Kenji, Hayashi, Ryo
• Granted Patent: US 8,581,243 B2
• Time in Patent Office: Days
• US Class Current: 257/57
• CPC Class Codes: H01L 29/4908 for thin film semiconductor, e.g. gate of TFT
• 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 bottom gate type thin-film transistor constituted of at least a substrate, a gate electrode, a gate insulating layer, a semiconductor layer, a source electrode and a drain electrode. At an interface between the gate electrode and the gate insulating layer, the interface has a difference between hill tops and dale bottoms of unevenness in the vertical direction, of 30 nm or less.

Claims

1. A bottom gate type thin-film transistor comprising at least a substrate, a gate electrode, a gate insulating layer, a semiconductor layer, a source electrode and a drain electrode, wherein;

at an interface between the gate electrode and the gate insulating layer, the interface has a difference between hill tops and dale bottoms of unevenness in the vertical direction, of 30 nm or less.

2. The thin-film transistor according to claim 1, wherein the difference between hill tops and dale bottoms of unevenness in the vertical direction at the interface between the gate insulating layer and the semiconductor layer is not more than the layer thickness of the semiconductor layer.

3. The thin-film transistor according to claim 1, wherein the gate electrode comprises a solid solution of indium oxide and tin oxide or a solid solution of indium oxide and zinc oxide.

4. The thin-film transistor according to claim 1, wherein the semiconductor layer is an amorphous oxide semiconductor film.

5. A process for fabricating a bottom gate type thin-film transistor, comprising at least a first step of forming a gate electrode on a substrate, a second step of forming a gate insulating layer on the gate electrode, a third step of forming a semiconductor layer on the gate insulating layer and a fourth step of forming a source electrode and a drain electrode on the semiconductor layer, wherein;

in the first step, the gate electrode formed on the substrate is an amorphous transparent electrode, and the amorphous transparent electrode is crystallized by being subjected to heat treatment later than the second step.

6. The process for fabricating a bottom gate type thin-film transistor according to claim 5, wherein the heat treatment is carried out after the fourth step of forming a source electrode and a drain electrode, and all the layers constituting the thin-film transistor stand amorphous until the heat treatment is carried out.

7. The process for fabricating a bottom gate type thin-film transistor according to claim 5, wherein all the layers constituting the thin-film transistor are formed at a temperature of 250°

C. or less.