THIN FILM TRANSISTOR DEVICE, METHOD FOR MANUFACTURING THE SAME AND DISPLAY APPARATUS HAVING THE SAME

Abstract

A thin film transistor device includes: an island shaped semiconductor layer; a metal film that covers at least a part of a source region and a drain region of the semiconductor layer; a gate insulating film that covers the semiconductor layer and the metal film; an interlayer insulating film that covers the gate insulating film; and a signal wire that lies on the interlayer insulating film. The gate insulating film and the interlayer insulating film are formed with contact hole that reaches the metal film. The signal wire is connected to the metal film through the contact hole.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing a sectional structure of a thin film transistor (TFT) device according to Embodiment 1 of the invention.

FIGS. 2A to 2D are sectional process views for explaining steps of a method for manufacturing the thin film transistor (TFT) device according to Embodiment 1 of the invention.

FIG. 3 is a sectional view showing a sectional structure of a thin film transistor (TFT) device according to Embodiment 2 of the invention.

FIG. 4 is a sectional view showing a sectional structure of a thin film transistor (TFT) device according to Embodiment 3 of the invention.

FIG. 5 is a sectional view showing a sectional structure which is used for making comparison with that of the thin film transistor (TFT) device according to Embodiment 3 of the invention.

Claims

1. A thin film transistor device comprising: a substrate;an island shaped semiconductor layer formed on the substrate, the semiconductor layer including a source region and a drain region;a metal film that covers at least a part of the source region and the drain region;a gate insulating film that covers the semiconductor layer and the metal film;an interlayer insulating film that covers the gate insulating film; anda signal wire that lies on the interlayer insulating film,wherein the gate insulating film and the interlayer insulating film are formed with contact hole that reaches the metal film, andwherein the signal wire is connected to the metal film through the contact hole.

2. The thin film transistor device according to claim 1, further comprising: a thin film transistor that includes the semiconductor layer, the metal film, the gate insulating film, and a gate electrode formed on the gate insulating film; anda storage capacitor that includes a lower electrode, an insulating capacitance film and an upper electrode,wherein the metal film extends so that a part of the metal film serves as at least a part of the lower electrode of the storage capacitor.

3. The thin film transistor device according to claim 2, wherein the semiconductor layer extends under the lower electrode of the storage capacitor.

4. The thin film transistor device according to claim 2, wherein the upper electrode of the storage capacitor is made of the same material as the gate electrode.

5. The thin film transistor device according to claim 2, wherein the insulating capacitance film of the storage capacitor is made of the same material as the gate insulating film.

6. The thin film transistor device according to claim 1, further comprising: a thin film transistor that includes the semiconductor layer, the metal film, the gate insulating film, and a gate electrode formed on the gate insulating film;a storage capacitor that includes a lower electrode, an insulating capacitance film and an upper electrode;an upper insulating film that covers the thin film transistor and the storage capacitor; anda pixel electrode that is formed on the upper insulating film,wherein the pixel electrode is electrically connected to the metal film through a contact hole running through the upper insulating film and the insulating film under the upper insulating film.

7. The thin film transistor device according to claim 1, wherein the metal film includes a high-melting metal or a conductive metallic compound.

8. The thin film transistor device according to claim 1, wherein the metal film contains at least one selected from the group consisting of Ti, Ta, W, Mo, TiN, TaN, HfN, WN, MoN, ZrN, VN, NbN, TiB2, ZrB2, HfB2, VB2, NbB2 and TaB2.

9. A method for manufacturing a thin film transistor device, the method comprising: forming an island shaped semiconductor layer on a substrate, the semiconductor layer including a source region and a drain region;forming a metal film that is connected to the semiconductor layer and covering at least a part of the source region and the drain region; andforming a gate insulating film covering the semiconductor layer and the metal film.

10. The method for manufacturing a thin film transistor device according to claim 9, wherein the metal film includes a high-melting metal or a conductive metallic compound.

11. The method for manufacturing a thin film transistor device according to claim 9, wherein the metal film contains at least one selected from the group consisting of Ti, Ta, W, Mo, TiN, TaN, HfN, WN, MoN, ZrN, VN, NbN, TiB2, ZrB2, HfB2, VB2, NbB2 and TaB2.

12. A display apparatus comprising, a display unit; anda thin film transistor device that drives the display unit, the thin film transistor device comprising: a substrate;an island shaped semiconductor layer formed on the substrate, the semiconductor layer including a source region and a drain region;a metal film that covers at least a part of the source region and the drain region;a gate insulating film that covers the semiconductor layer and the metal film;an interlayer insulating film that covers the gate insulating film; anda signal wire that lies on the interlayer insulating film,wherein the gate insulating film and the interlayer insulating film are formed with a contact hole that reaches the metal film, andwherein the signal wire is connected to the metal film through the contact hole.