A metal element of a metal film is introduced into the oxide semiconductor film by performing heat treatment in the state where the oxide semiconductor film is in contact with the metal film, so that a low-resistance region having resistance lower than that of a channel formation region is formed. A region of the metal film, which is in contact with the oxide semiconductor film, becomes a metal oxide insulating film by the heat treatment. After that, an unnecessary metal film is removed. Thus, the metal oxide insulating film can be formed over the low-resistance region.

The present invention provides an array substrate and a manufacturing method thereof. The manufacturing method of the array substrate according to the present invention forms a gate electrode in the same metal layer with source and drain electrodes and divides a common electrode layer that is conventionally in the form of an entire surface into two portions, of which one serves as a common electrode, while the other portion feeds an input of a gate scan signal thereby eliminating an operation of forming an interlayer insulation layer and thus reducing manufacturing cost of the operation. The array substrate of the present invention comprises a gate electrode that is formed in the same metal layer with source and drain electrodes so that no interlayer insulation layer is present between the gate electrode and the source and drain electrodes, thereby simplifying the structure and reducing the manufacturing cost of the array substrate.

A novel semiconductor device including an oxide semiconductor is provided. In particular, a planar semiconductor device including an oxide semiconductor is provided. A semiconductor device including an oxide semiconductor and having large on-state current is provided. The semiconductor device includes an oxide insulating film, an oxide semiconductor film over the oxide insulating film, a source electrode and a drain electrode in contact with the oxide semiconductor film, a gate insulating film between the source electrode and the drain electrode, and a gate electrode overlapping the oxide semiconductor film with the gate insulating film. The oxide semiconductor film includes a first region overlapped with the gate electrode and a second region not overlapped with the gate electrode, the source electrode, and the drain electrode. The first region and the second region have different impurity element concentrations. The gate electrode, the source electrode, and the drain electrode contain the same metal element.

The present invention proposes a TFT, an array substrate, and a method of forming a TFT. The TFT includes a substrate, a buffer layer, a patterned poly-si layer, an isolation layer, a gate layer, and a source/drain pattern layer. The poly-si layer includes a heavily doped source and a heavily doped drain, and a channel. The gate layer includes a first gate area and a second gate area. The source/drain pattern layer includes a source pattern, a drain pattern and a bridge pattern, with the source pattern electrically connecting the heavily doped source, the drain pattern electrically connecting the heavily doped drain, and one end of the bridge pattern connecting the first gate area and the second gate area. The driving ability of the present inventive TFT is enhanced without affecting the leakage current.

A reduction in contaminating impurities in a TFT, and a TFT which is reliable, is obtained in a semiconductor device which uses the TFT. By removing contaminating impurities residing in a film interface of the TFT using a solution containing fluorine, a reliable TFT can be obtained.

The present invention discloses a thin film transistor (TFT), an array substrate, and fabrication methods thereof, and a display device. The TFT includes a gate, an oxide active layer, a source, and a drain formed on a substrate, wherein a source and drain transition layer is provided between the oxide active layer and the source, the drain. One patterning process is reduced and one mask process is saved through forming the source and drain transition layer between the oxide active layer and the source, the drain, thus effectively simplifying the fabrication procedure. At the same time, the additionally provided source and drain transition layer may prevent the oxide active layer from being corroded during etching, also effectively reduce threshold voltage (V.sub.th) drift of the TFT, improve I.sub.on (on-state current) /I.sub.off (off-state current), and enhance thermal stability.

In a semiconductor device including a transistor, the transistor is provided over a first insulating film, and the transistor includes an oxide semiconductor film over the first insulating film, a gate insulating film over the oxide semiconductor film, a gate electrode over the gate insulating film, a second insulating film over the oxide semiconductor film and the gate electrode, and a source and a drain electrodes electrically connected to the oxide semiconductor film. The first insulating film includes oxygen. The second insulating film includes hydrogen. The oxide semiconductor film includes a first region in contact with the gate insulating film and a second region in contact with the second insulating film. The first insulating film includes a third region overlapping with the first region and a fourth region overlapping with the second region. The impurity element concentration of the fourth region is higher than that of the third region.

The present invention provides an array substrate and a manufacturing method thereof. Etching stop patterns or auxiliary conductive patterns of a patterned auxiliary conductive layer are disposed corresponding to heavily doped regions of a patterned semiconductor layer, and source/drain electrodes may be electrically connected to the heavily doped regions via the etching stop patterns or the auxiliary conductive patterns. The production yield and the uniformity of electrical properties may be enhanced accordingly.

In accordance with some embodiments of the disclosed subject of matter, a TFT array substrate, a method for fabricating the TFT array substrate, and a display panel that comprises the TFT array substrate are provided. In some embodiments, the TFT array substrate comprises: a substrate; an active layer comprising a first region, a source region, a drain region, and a second region between the drain region and the first region; a gate electrode above the first insulating layer, wherein the gate electrode substantially covers the first region; and a first light-shielding layer that overlaps with the first region and substantially covers the second region.

A device for manufacturing an array substrate includes an exposure device for using a halftone mask to form a photoresist pattern layer on a gate insulation layer of a substrate. A polysilicon pattern layer is disposed on the substrate. A gate insulation layer covers the polysilicon pattern layer. The photoresist pattern layer includes a hollow portion corresponding to a heavily doping region of the polysilicon pattern layer, a first photoresist portion corresponding to a lightly doping region of the polysilicon pattern layer, and a second photoresist portion corresponding to an undoped region of the polysilicon pattern layer. The first photoresist portion is thinner than the second photoresist portion. A doping device is used for performing one doping process to the polysilicon pattern layer such that the heavily doping region and the lightly doping region are formed simultaneously.