Abstract: A metal oxide layer is in contact with an interlayer insulating layer covering a transistor, and has a stacked-layer structure including a first metal oxide layer having an amorphous structure and a second metal oxide layer having a polycrystalline structure. In the first metal oxide layer, there are no crystal grain boundaries, and grid intervals are wide as compared to those in a metal oxide layer in a crystalline state; thus, the first metal oxide layer easily traps moisture between the lattices. In the second metal oxide layer having a polycrystalline structure, crystal parts other than crystal grain boundary portions have dense structures and extremely low moisture permeability. Thus, the structure in which the metal oxide layer including the first metal oxide layer and the second metal oxide layer is in contact with the interlayer insulating layer can effectively prevent moisture permeation into the transistor.

Abstract: Provided is a semiconductor device with favorable electrical characteristics. Provided is a semiconductor device with stable electrical characteristics. Provided is a manufacturing method of a semiconductor device with a high yield. The manufacturing method includes a first step of forming an insulating film over a substrate, a second step of transferring the substrate in an atmospheric atmosphere, a third step of heating the insulating film, and a fourth step of forming a metal oxide film. The third step and the fourth step are successively performed in an atmosphere where water vapor partial pressure is lower than water vapor partial pressure in the atmospheric air.

Abstract: A semiconductor device having favorable electrical characteristics is provided. A highly reliable semiconductor device is provided. The semiconductor device includes a metal oxide. The semiconductor device includes a gate electrode, a first insulating film over the gate electrode, the metal oxide over the first insulating film, a pair of electrodes over the metal oxide, and a second insulating film in contact with the metal oxide. The metal oxide includes a first metal oxide and a second metal oxide in contact with a top surface of the first metal oxide. The first metal oxide and the second metal oxide each contain In, an element M (M is gallium, aluminum, silicon, or the like), and Zn. The first metal oxide includes a region having lower crystallinity than the second metal oxide. The second insulating film includes a region whose thickness is smaller than that of the second metal oxide.

Abstract: To provide a sputtering apparatus capable of forming a semiconductor film in which impurities such as hydrogen or water are reduced. The sputtering apparatus is capable of forming a semiconductor film and includes a deposition chamber, a gas supply device connected to the deposition chamber, a gas refining device connected to the gas supply device, a vacuum pump for evacuating the deposition chamber, a target disposed in the deposition chamber, and a cathode disposed to face the target. The gas supply device is configured to supply at least one of an argon gas, an oxygen gas, and a nitrogen gas. The partial pressure of hydrogen molecules is lower than or equal to 0.01 Pa and the partial pressure of water molecules is lower than or equal to 0.0001 Pa in the deposition chamber.

Abstract: To provide a semiconductor device which has transistor characteristics with little variation and includes an oxide semiconductor. The semiconductor device includes an insulating film over a conductive film and an oxide semiconductor film over the insulating film. The oxide semiconductor film includes a first oxide semiconductor layer, a second oxide semiconductor layer over the first oxide semiconductor layer, and a third oxide semiconductor layer over the second oxide semiconductor layer. The energy level of a bottom of a conduction band of the second oxide semiconductor layer is lower than those of the first and third oxide semiconductor layers. An end portion of the second oxide semiconductor layer is positioned on an inner side than an end portion of the first oxide semiconductor layer.

Abstract: A highly reliable semiconductor device that includes a transistor including an oxide semiconductor, which can display a high-definition image and can be manufactured with a high yield. The semiconductor device includes a pixel portion including a plurality of pixels, a gate signal line driver circuit portion, and a source signal line driver circuit portion including a first circuit that controls timing of sampling video signals and a second circuit that samples the video signals in accordance with the timing and then inputs the sampled video signals to the pixels. The second circuit includes a plurality of transistors in each of which an oxide semiconductor stacked layer is used as a channel formation region, the first circuit and the second circuit are electrically connected to each other by a wiring, and the wiring is electrically connected to gates of at least two transistors of the plurality of transistors.

Abstract: To provide a semiconductor device which has transistor characteristics with little variation and includes an oxide semiconductor. The semiconductor device includes an insulating film over a conductive film and an oxide semiconductor film over the insulating film. The oxide semiconductor film includes a first oxide semiconductor layer, a second oxide semiconductor layer over the first oxide semiconductor layer, and a third oxide semiconductor layer over the second oxide semiconductor layer. The energy level of a bottom of a conduction band of the second oxide semiconductor layer is lower than those of the first and third oxide semiconductor layers. An end portion of the second oxide semiconductor layer is positioned on an inner side than an end portion of the first oxide semiconductor layer.

Abstract: Stable electrical characteristics of a transistor including an oxide semiconductor layer are achieved. A highly reliable semiconductor device including the transistor is provided. The semiconductor device includes a multilayer film formed of an oxide layer and an oxide semiconductor layer, a gate insulating film in contact with the oxide layer, and a gate electrode overlapping with the multilayer film with the gate insulating film interposed therebetween. The oxide layer contains a common element to the oxide semiconductor layer and has a large energy gap than the oxide semiconductor layer. The composition between the oxide layer and the oxide semiconductor layer gradually changes.

Abstract: To provide a semiconductor device which has transistor characteristics with little variation and includes an oxide semiconductor. The semiconductor device includes an insulating film over a conductive film and an oxide semiconductor film over the insulating film. The oxide semiconductor film includes a first oxide semiconductor layer, a second oxide semiconductor layer over the first oxide semiconductor layer, and a third oxide semiconductor layer over the second oxide semiconductor layer. The energy level of a bottom of a conduction band of the second oxide semiconductor layer is lower than those of the first and third oxide semiconductor layers. An end portion of the second oxide semiconductor layer is positioned on an inner side than an end portion of the first oxide semiconductor layer.

Abstract: Stable electrical characteristics of a transistor including an oxide semiconductor layer are achieved. A highly reliable semiconductor device including the transistor is provided. The semiconductor device includes a multilayer film formed of an oxide layer and an oxide semiconductor layer, a gate insulating film in contact with the oxide layer, and a gate electrode overlapping with the multilayer film with the gate insulating film interposed therebetween. The oxide layer contains a common element to the oxide semiconductor layer and has a large energy gap than the oxide semiconductor layer. The composition between the oxide layer and the oxide semiconductor layer gradually changes.

Abstract: Provided is a semiconductor device including an oxide semiconductor and having stable electrical characteristics. Specifically, a semiconductor device including an oxide semiconductor and including a gate insulating film with favorable characteristics is provided. Further, a method for manufacturing the semiconductor device is provided. The semiconductor device includes a gate electrode, a gate insulating film over the gate electrode, an oxide semiconductor film over the gate insulating film, and a source electrode and a drain electrode in contact with the oxide semiconductor film. The gate insulating film includes at least a silicon oxynitride film and an oxygen release type oxide film which is formed over the silicon oxynitride film. The oxide semiconductor film is formed on and in contact with the oxygen release type oxide film.

Abstract: To provide a semiconductor device which has transistor characteristics with little variation and includes an oxide semiconductor. The semiconductor device includes an insulating film over a conductive film and an oxide semiconductor film over the insulating film. The oxide semiconductor film includes a first oxide semiconductor layer, a second oxide semiconductor layer over the first oxide semiconductor layer, and a third oxide semiconductor layer over the second oxide semiconductor layer. The energy level of a bottom of a conduction band of the second oxide semiconductor layer is lower than those of the first and third oxide semiconductor layers. An end portion of the second oxide semiconductor layer is positioned on an inner side than an end portion of the first oxide semiconductor layer.

Abstract: A highly reliable semiconductor device that includes a transistor including an oxide semiconductor, which can display a high-definition image and can be manufactured with a high yield. The semiconductor device includes a pixel portion including a plurality of pixels, a gate signal line driver circuit portion, and a source signal line driver circuit portion including a first circuit that controls timing of sampling video signals and a second circuit that samples the video signals in accordance with the timing and then inputs the sampled video signals to the pixels. The second circuit includes a plurality of transistors in each of which an oxide semiconductor stacked layer is used as a channel formation region, the first circuit and the second circuit are electrically connected to each other by a wiring, and the wiring is electrically connected to gates of at least two transistors of the plurality of transistors.

Abstract: To provide a semiconductor device including an oxide semiconductor, which has stable electric characteristics and has high reliability. To provide a method for manufacturing the semiconductor device. The semiconductor device includes a gate electrode, a gate insulating film formed over the gate electrode, an oxide semiconductor film formed over the gate insulating film, a source electrode and a drain electrode formed over the oxide semiconductor film, and a protective film. The protective film includes a metal oxide film, and the metal oxide film has a film density of higher than or equal to 3.2 g/cm3.

Abstract: In a semiconductor device including an oxide semiconductor, a change in electrical characteristics is inhibited and reliability is improved. The semiconductor device is manufactured by a method including first to fourth steps. The first step includes a step of forming an oxide semiconductor film, the second step includes a step of forming an oxide insulating film over the oxide semiconductor film, the third step includes a step of forming a protective film over the oxide insulating film, and the fourth step includes a step of adding oxygen to the oxide insulating film through the protective film. In the first step, the oxide semiconductor film is formed under a condition in which an oxygen vacancy is formed. The oxygen from the oxide insulating film fills the oxygen vacancy after the fourth step.

Abstract: To provide a semiconductor device including an oxide semiconductor, which has stable electric characteristics and has high reliability. To provide a method for manufacturing the semiconductor device. The semiconductor device includes a gate electrode, a gate insulating film formed over the gate electrode, an oxide semiconductor film formed over the gate insulating film, a source electrode and a drain electrode formed over the oxide semiconductor film, and a protective film. The protective film includes a metal oxide film, and the metal oxide film has a film density of higher than or equal to 3.2 g/cm3.

Abstract: A metal oxide layer is in contact with an interlayer insulating layer covering a transistor, and has a stacked-layer structure including a first metal oxide layer having an amorphous structure and a second metal oxide layer having a polycrystalline structure. In the first metal oxide layer, there are no crystal grain boundaries, and grid intervals are wide as compared to those in a metal oxide layer in a crystalline state; thus, the first metal oxide layer easily traps moisture between the lattices. In the second metal oxide layer having a polycrystalline structure, crystal parts other than crystal grain boundary portions have dense structures and extremely low moisture permeability. Thus, the structure in which the metal oxide layer including the first metal oxide layer and the second metal oxide layer is in contact with the interlayer insulating layer can effectively prevent moisture permeation into the transistor.

Abstract: A highly reliable semiconductor device that includes a transistor including an oxide semiconductor, which can display a high-definition image and can be manufactured with a high yield. The semiconductor device includes a pixel portion including a plurality of pixels, a gate signal line driver circuit portion, and a source signal line driver circuit portion including a first circuit that controls timing of sampling video signals and a second circuit that samples the video signals in accordance with the timing and then inputs the sampled video signals to the pixels. The second circuit includes a plurality of transistors in each of which an oxide semiconductor stacked layer is used as a channel formation region, the first circuit and the second circuit are electrically connected to each other by a wiring, and the wiring is electrically connected to gates of at least two transistors of the plurality of transistors.

Abstract: To provide a semiconductor device which has transistor characteristics with little variation and includes an oxide semiconductor. The semiconductor device includes an insulating film over a conductive film and an oxide semiconductor film over the insulating film. The oxide semiconductor film includes a first oxide semiconductor layer, a second oxide semiconductor layer over the first oxide semiconductor layer, and a third oxide semiconductor layer over the second oxide semiconductor layer. The energy level of a bottom of a conduction band of the second oxide semiconductor layer is lower than those of the first and third oxide semiconductor layers. An end portion of the second oxide semiconductor layer is positioned on an inner side than an end portion of the first oxide semiconductor layer.

Abstract: A metal oxide layer is in contact with an interlayer insulating layer covering a transistor, and has a stacked-layer structure including a first metal oxide layer having an amorphous structure and a second metal oxide layer having a polycrystalline structure. In the first metal oxide layer, there are no crystal grain boundaries, and grid intervals are wide as compared to those in a metal oxide layer in a crystalline state; thus, the first metal oxide layer easily traps moisture between the lattices. In the second metal oxide layer having a polycrystalline structure, crystal parts other than crystal grain boundary portions have dense structures and extremely low moisture permeability. Thus, the structure in which the metal oxide layer including the first metal oxide layer and the second metal oxide layer is in contact with the interlayer insulating layer can effectively prevent moisture permeation into the transistor.