Abstract: To provide a semiconductor device including a transistor in which an oxide semiconductor is used and on-state current is high. In a semiconductor device including a first transistor provided in a driver circuit portion and a second transistor provided in a pixel portion, the first transistor and the second transistor have different structures. Furthermore, the first transistor and the second transistor are transistors having a top-gate structure in which conductive films serving as a gate electrode, a source electrode, and a drain electrode do not overlap. Furthermore, in an oxide semiconductor film, an impurity element is contained in a region which does not overlap with the gate electrode, the source electrode, and the drain electrode.

Abstract: A semiconductor device including a transistor having a reduced number of oxygen vacancies in a channel formation region of an oxide semiconductor with stable electrical characteristics or high reliability is provided. A gate insulating film is formed over a gate electrode; an oxide semiconductor layer is formed over the gate insulating film; an oxide layer is formed over the oxide semiconductor layer by a sputtering method to form an stacked-layer oxide film including the oxide semiconductor layer and the oxide layer; the stacked-layer oxide film is processed into a predetermined shape; a conductive film containing Ti as a main component is formed over the stacked-layer oxide film; the conductive film is etched to form source and drain electrodes and a depression portion on a back channel side; and portions of the stacked-layer oxide film in contact with the source and drain electrodes are changed to an n-type by heat treatment.

Abstract: A method for manufacturing a semiconductor device includes the steps of forming a first conductive film over a substrate; forming an insulating film over the first conductive film; forming an oxide semiconductor film over the insulating film to overlap with the first conductive film; forming a second conductive film including a metal film containing molybdenum as its main component and a metal film containing copper as its main component over the oxide semiconductor film; and etching the second conductive film by an etchant. At the time of etching the second conductive film by the etchant, the oxide semiconductor film is used as an etching stopper film. In addition, the etchant which can be used for a transistor including the oxide semiconductor film is provided.

Abstract: A transistor includes a multilayer film in which an oxide semiconductor film and an oxide film are stacked, a gate electrode, and a gate insulating film. The multilayer film overlaps with the gate electrode with the gate insulating film interposed therebetween. The multilayer film has a shape having a first angle between a bottom surface of the oxide semiconductor film and a side surface of the oxide semiconductor film and a second angle between a bottom surface of the oxide film and a side surface of the oxide film. The first angle is acute and smaller than the second angle. Further, a semiconductor device including such a transistor is manufactured.

Abstract: A semiconductor device including a transistor having a reduced number of oxygen vacancies in a channel formation region of an oxide semiconductor with stable electrical characteristics or high reliability is provided. A gate insulating film is formed over a gate electrode; an oxide semiconductor layer is formed over the gate insulating film; an oxide layer is formed over the oxide semiconductor layer by a sputtering method to form an stacked-layer oxide film including the oxide semiconductor layer and the oxide layer; the stacked-layer oxide film is processed into a predetermined shape; a conductive film containing Ti as a main component is formed over the stacked-layer oxide film; the conductive film is etched to form source and drain electrodes and a depression portion on a back channel side; and portions of the stacked-layer oxide film in contact with the source and drain electrodes are changed to an n-type by heat treatment.

Abstract: A transistor includes a multilayer film in which an oxide semiconductor film and an oxide film are stacked, a gate electrode, and a gate insulating film. The multilayer film overlaps with the gate electrode with the gate insulating film interposed therebetween. The multilayer film has a shape having a first angle between a bottom surface of the oxide semiconductor film and a side surface of the oxide semiconductor film and a second angle between a bottom surface of the oxide film and a side surface of the oxide film. The first angle is acute and smaller than the second angle. Further, a semiconductor device including such a transistor is manufactured.

Abstract: Provided is a transistor with small parasitic capacitance or high frequency characteristics or a semiconductor device including the transistor. An oxide semiconductor film includes a first region in contact with a first conductive film, a second region in contact with a first insulating film, a third region in contact with a third insulating film, a fourth region in contact with a second insulating film, and a fifth region in contact with a second conductive film. The first insulating film is positioned over the first conductive film and the oxide semiconductor film. The second insulating film is positioned over the second conductive film and the oxide semiconductor film. The third insulating film is positioned over the first insulating film, the second insulating film, and the oxide semiconductor film. The third conductive film and the oxide semiconductor film partly overlap with each other with the third insulating film provided therebetween.

Abstract: A transistor includes a multilayer film in which an oxide semiconductor film and an oxide film are stacked, a gate electrode, and a gate insulating film. The multilayer film overlaps with the gate electrode with the gate insulating film interposed therebetween. The multilayer film has a shape having a first angle between a bottom surface of the oxide semiconductor film and a side surface of the oxide semiconductor film and a second angle between a bottom surface of the oxide film and a side surface of the oxide film. The first angle is acute and smaller than the second angle. Further, a semiconductor device including such a transistor is manufactured.

Abstract: A semiconductor device including a transistor and a wiring electrically connected to the transistor each of which has excellent electrical characteristics because of specific structures thereover is provided. A first conductive film, a first insulating film over the first conductive film, a second conductive film over the first insulating film, a second insulating film over the second conductive film, a third conductive film electrically connected to the first conductive film through an opening provided in the first insulating film and the second insulating film, and a third insulating film over the third conductive film are provided. The third conductive film includes indium, tin, and oxygen, and the third insulating film includes silicon and nitrogen and the number of ammonia molecules released from the third insulating film is less than or equal to 1×1015 molecules/cm3 by thermal desorption spectroscopy.

Abstract: A transistor includes a multilayer film in which an oxide semiconductor film and an oxide film are stacked, a gate electrode, and a gate insulating film. The multilayer film overlaps with the gate electrode with the gate insulating film interposed therebetween. The multilayer film has a shape having a first angle between a bottom surface of the oxide semiconductor film and a side surface of the oxide semiconductor film and a second angle between a bottom surface of the oxide film and a side surface of the oxide film. The first angle is acute and smaller than the second angle. Further, a semiconductor device including such a transistor is manufactured.

Abstract: To provide a semiconductor device including a transistor in which an oxide semiconductor is used and on-state current is high. In a semiconductor device including a first transistor provided in a driver circuit portion and a second transistor provided in a pixel portion, the first transistor and the second transistor have different structures. Furthermore, the first transistor and the second transistor are transistors having a top-gate structure in which conductive films serving as a gate electrode, a source electrode, and a drain electrode do not overlap. Furthermore, in an oxide semiconductor film, an impurity element is contained in a region which does not overlap with the gate electrode, the source electrode, and the drain electrode.

Abstract: 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.

Abstract: The semiconductor device includes an oxide semiconductor; a source electrode and a drain electrode in contact with the oxide semiconductor; a gate insulating film over the oxide semiconductor, the source electrode, and the drain electrode; and a gate electrode overlapping the oxide semiconductor, part of the source electrode, and part of the drain electrode with the gate insulating film positioned therebetween. The source electrode and the drain electrode each include a Cu—X alloy film (X is Mn, Ni, Cr, Fe, Co, Mo, Ta, or Ti), and the thickness of a region of the oxide semiconductor over which neither the source electrode nor the drain electrode is provided is smaller than the thicknesses of regions of the oxide semiconductor over which the source electrode and the drain electrode are provided.

Abstract: A new semiconductor device in which a metal film containing Cu is used for a transistor including an oxide semiconductor film, and a method for manufacturing the semiconductor device are provided. The semiconductor device includes a transistor including a first gate electrode layer, a first gate insulating film over the first gate electrode layer, an oxide semiconductor film that is provided over the first gate insulating film to overlap the first gate electrode layer, a pair of electrode layers electrically connected to the oxide semiconductor film, a second gate insulating film over the oxide semiconductor film and the pair of electrode layers, and a second gate electrode layer that is over the second gate insulating film to overlap the oxide semiconductor film. The pair of electrode layers includes a Cu—X alloy film (X is Mn, Ni, Cr, Fe, Co, Mo, Ta, or Ti).

Abstract: A method for manufacturing a semiconductor device includes the steps of forming a first conductive film over a substrate; forming an insulating film over the first conductive film; forming an oxide semiconductor film over the insulating film to overlap with the first conductive film; forming a second conductive film including a metal film containing molybdenum as its main component and a metal film containing copper as its main component over the oxide semiconductor film; and etching the second conductive film by an etchant. At the time of etching the second conductive film by the etchant, the oxide semiconductor film is used as an etching stopper film. In addition, the etchant which can be used for a transistor including the oxide semiconductor film is provided.

Abstract: The stability of a step of processing a wiring formed using copper, aluminum, gold, silver, molybdenum, or the like is increased. Moreover, the concentration of impurities in a semiconductor film is reduced. Moreover, the electrical characteristics of a semiconductor device are improved. In a transistor including an oxide semiconductor film, an oxide film in contact with the oxide semiconductor film, and a pair of conductive films being in contact with the oxide film and including copper, aluminum, gold, silver, molybdenum, or the like, the oxide film has a plurality of crystal parts and has c-axis alignment in the crystal parts, and the c-axes are aligned in a direction parallel to a normal vector of a top surface of the oxide semiconductor film or the oxide film.

Abstract: The stability of steps of processing a wiring formed using copper or the like is increased. The concentration of impurities in a semiconductor film is reduced. Electrical characteristics of a semiconductor device are improved. A semiconductor device includes a semiconductor film, a pair of first protective films in contact with the semiconductor film, a pair of conductive films containing copper or the like in contact with the pair of first protective films, a pair of second protective films in contact with the pair of conductive films on the side opposite the pair of first protective films, a gate insulating film in contact with the semiconductor film, and a gate electrode overlapping with the semiconductor film with the gate insulating film therebetween. In a cross section, side surfaces of the pair of second protective films are located on the outer side of side surfaces of the pair of conductive films.

Abstract: A semiconductor device including a transistor having a reduced number of oxygen vacancies in a channel formation region of an oxide semiconductor with stable electrical characteristics or high reliability is provided. A gate insulating film is formed over a gate electrode; an oxide semiconductor layer is formed over the gate insulating film; an oxide layer is formed over the oxide semiconductor layer by a sputtering method to form an stacked-layer oxide film including the oxide semiconductor layer and the oxide layer; the stacked-layer oxide film is processed into a predetermined shape; a conductive film containing Ti as a main component is formed over the stacked-layer oxide film; the conductive film is etched to form source and drain electrodes and a depression portion on a back channel side; and portions of the stacked-layer oxide film in contact with the source and drain electrodes are changed to an n-type by heat treatment.

Abstract: A transistor includes a multilayer film in which an oxide semiconductor film and an oxide film are stacked, a gate electrode, and a gate insulating film. The multilayer film overlaps with the gate electrode with the gate insulating film interposed therebetween. The multilayer film has a shape having a first angle between a bottom surface of the oxide semiconductor film and a side surface of the oxide semiconductor film and a second angle between a bottom surface of the oxide film and a side surface of the oxide film. The first angle is acute and smaller than the second angle. Further, a semiconductor device including such a transistor is manufactured.

Abstract: It is an object to provide a semiconductor device including an oxide semiconductor, which has stable electric characteristics and high reliability. A semiconductor device having a stacked-layer structure of a gate insulating layer; a first gate electrode in contact with one surface of the gate insulating layer; an oxide semiconductor layer in contact with the other surface of the gate insulating layer and overlapping with the first gate electrode; and a source electrode, a drain electrode, and an oxide insulating layer which are in contact with the oxide semiconductor layer is provided, in which the nitrogen concentration of the oxide semiconductor layer is 2×1019 atoms/cm3 or lower and the source electrode and the drain electrode include one or more of tungsten, platinum, and molybdenum.