A thin film transistor substrate includes a gate electrode disposed on a substrate; a semiconductor layer disposed on the substrate that partially overlaps the gate electrode and includes an oxide semiconductor material; and a source electrode and a drain electrode disposed on the semiconductor layer, where the drain electrode is spaced apart from the source electrode. The source electrode and the drain electrode each include a barrier layer and a main wiring layer, the a main wiring layer is disposed on the barrier layer, and the barrier layer includes a first metal layer disposed on the semiconductor layer, and a second metal layer disposed on the first metal layer.

A display substrate includes a base substrate comprising a plurality of sub-pixels, a first switching element disposed on the base substrate and electrically connected to a gate line extending in a first direction and a data line extending in a second direction crossing the first direction, a color filter layer disposed on the switching element and comprising a red color filter, a green color filter, a blue color filter and a white color filter alternately disposed on the plurality of sub-pixels, respectively, a column spacer disposed on the color filter and comprising the same material as that of the white color filter, an insulation layer disposed on the color filter and the column spacer and a pixel electrode disposed on the insulation layer.

An object is to manufacture a highly reliable semiconductor device including a thin film transistor with stable electric characteristics. In a method for manufacturing a semiconductor device including a thin film transistor in which an oxide semiconductor film is used for a semiconductor layer including a channel formation region, heat treatment (for dehydration or dehydrogenation) is performed to improve the purity of the oxide semiconductor film and reduce impurities including moisture or the like. After that, slow cooling is performed under an oxygen atmosphere. Besides impurities including moisture or the like exiting in the oxide semiconductor film, heat treatment causes reduction of impurities including moisture or the like exiting in a gate insulating layer and those in interfaces between the oxide semiconductor film and films which are provided over and below the oxide semiconductor and in contact therewith.

A method for manufacturing a semiconductor device includes the steps of forming a first insulating film over a first gate electrode over a substrate while heated at a temperature higher than or equal to 450 C. and lower than the strain point of the substrate, forming a first oxide semiconductor film over the first insulating film, adding oxygen to the first oxide semiconductor film and then forming a second oxide semiconductor film over the first oxide semiconductor film, and performing heat treatment so that part of oxygen contained in the first oxide semiconductor film is transferred to the second oxide semiconductor film.

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.

A semiconductor device including a nonvolatile memory cell in which a writing transistor which includes an oxide semiconductor, a reading transistor which includes a semiconductor material different from that of the writing transistor, and a capacitor are included is provided. Data is written to the memory cell by turning on the writing transistor and applying a potential to a node where a source electrode (or a drain electrode) of the writing transistor, one electrode of the capacitor, and a gate electrode of the reading transistor are electrically connected, and then turning off the writing transistor, so that the predetermined amount of charge is held in the node. Further, when a p-channel transistor is used as the reading transistor, a reading potential is a positive potential.

The present invention provides a thin-film transistor in which transistor characteristics such as drain current and threshold voltage are improved, and a method of manufacturing the same. The present invention provides a thin-film transistor provided with a source electrode (108), a drain electrode (109), a semiconductor layer (105), a gate electrode (103), and an insulating layer (104); wherein the semiconductor layer (105) contains a composite metal oxide obtained by adding to a first metal oxide an oxide having an oxygen dissociation energy that is at least 200 kJ/mol greater than the oxygen dissociation energy of the first metal oxide, whereby the amount of oxygen vacancy is controlled; and the insulating layer (104) is provided with an SiO.sub.2 layer, a high-permittivity first layer, and a high-permittivity second layer, whereby the dipoles generated at the boundary between the SiO.sub.2 layer and the high-permittivity layers are used to control the threshold voltage.

To provide a highly reliable semiconductor device using an oxide semiconductor. The semiconductor device includes a first electrode layer; a second electrode layer positioned over the first electrode layer and including a stacked-layer structure of a first conductive layer and a second conductive layer; and an oxide semiconductor film and an insulating film positioned between the first electrode layer and the second electrode layer in a thickness direction. The first conductive layer and the insulating film have a first opening portion in a region overlapping with the first electrode layer, The oxide semiconductor film has a second opening portion in a region overlapping with the first opening portion. The second conductive layer is in contact with the first electrode layer exposed in the first opening portion and the second opening portion.

A method of manufacturing a thin-film transistor (TFT) substrate including a thin-film transistor having a CuMn alloy film. The method includes controlling a contact resistance of a surface of the CuMn alloy film on the basis of a contact angle of the surface of the CuMn alloy film.

A semiconductor device which includes a transistor having a miniaturized structure is provided. A first insulator is provided over a stack in which a semiconductor, a first conductor, and a second conductor are stacked in this order. Over the first insulator, an etching mask is formed. Using the etching mask, the first insulator and the second conductor are etched until the first conductor is exposed. After etching the first conductor until the semiconductor is exposed so as to form a groove having a smaller width than the second conductor, a second insulator and a third conductor are formed sequentially.