Abstract: A semiconductor device with favorable electrical characteristics is provided. The semiconductor device includes an insulating layer, a semiconductor layer over the insulating layer, a source electrode layer and a drain electrode layer electrically connected to the semiconductor layer, a gate insulating film over the semiconductor layer, the source electrode layer, and the drain electrode layer, and a gate electrode layer overlapping with part of the semiconductor layer, part of the source electrode layer, and part of the drain electrode layer with the gate insulating film therebetween. A cross section of the semiconductor layer in the channel width direction is substantially triangular or substantially trapezoidal. The effective channel width is shorter than that for a rectangular cross section.

Abstract: Provided is a semiconductor device that can be miniaturized in a simple process and that can prevent deterioration of electrical characteristics due to miniaturization. The semiconductor device includes an oxide semiconductor layer, a first conductor in contact with the oxide semiconductor layer, and an insulator in contact with the first conductor. Further, an opening portion is provided in the oxide semiconductor layer, the first conductor, and the insulator. In the opening portion, side surfaces of the oxide semiconductor layer, the first conductor, and the insulator are aligned, and the oxide semiconductor layer and the first conductor are electrically connected to a second conductor by side contact.

Abstract: A semiconductor device using oxide semiconductor with favorable electrical characteristics, or a highly reliable semiconductor device is provided. A semiconductor device is manufactured by: forming an oxide semiconductor layer over an insulating surface; forming source and drain electrodes over the oxide semiconductor layer; forming an insulating film and a conductive film in this order over the oxide semiconductor layer and the source and drain electrodes; etching part of the conductive film and insulating film to form a gate electrode and a gate insulating layer, and etching part of the upper portions of the source and drain electrodes to form a first covering layer containing a constituent element of the source and drain electrodes and in contact with the side surface of the gate insulating layer; oxidizing the first covering layer to form a second covering layer; and forming a protective insulating layer containing an oxide over the second covering layer.

Abstract: Provided is a semiconductor device in which deterioration of electric characteristics which becomes more noticeable as the semiconductor device is miniaturized can be suppressed. The semiconductor device includes a first oxide film, an oxide semiconductor film over the first oxide film, a source electrode and a drain electrode in contact with the oxide semiconductor film, a second oxide film over the oxide semiconductor film, the source electrode, and the drain electrode, a gate insulating film over the second oxide film, and a gate electrode in contact with the gate insulating film. A top end portion of the oxide semiconductor film is curved when seen in a channel width direction.

Abstract: Provided is a semiconductor device which can suppress an increase in oxygen vacancies in an oxide semiconductor layer and a manufacturing method of the semiconductor device. The semiconductor device includes a first oxide semiconductor layer over the first insulating layer; a second oxide semiconductor layer over the first oxide semiconductor layer; a third oxide semiconductor layer over the second oxide semiconductor layer; a source electrode layer and a drain electrode layer each over the third oxide semiconductor layer; a fourth semiconductor layer over the source and drain electrode layers, and the third oxide semiconductor layer; a gate insulating layer over the fourth oxide semiconductor layer; a gate electrode layer over the gate electrode layer and overlapping with the source and drain electrode layers, and the fourth oxide semiconductor layer; and a second insulating layer over the first insulating layer, and the source, gate, and drain electrode layers.

Abstract: Provided is a semiconductor device in which deterioration of electric characteristics which becomes more noticeable as the semiconductor device is miniaturized can be suppressed. The semiconductor device includes a first oxide film, an oxide semiconductor film over the first oxide film, a source electrode and a drain electrode in contact with the oxide semiconductor film, a second oxide film over the oxide semiconductor film, the source electrode, and the drain electrode, a gate insulating film over the second oxide film, and a gate electrode in contact with the gate insulating film. A top end portion of the oxide semiconductor film is curved when seen in a channel width direction.

Abstract: A semiconductor device with a structure in which an increase in the number of oxygen vacancies in an oxide semiconductor layer can be suppressed and a method for manufacturing the semiconductor device are provided. The semiconductor device includes an oxide insulating layer; intermediate layers apart from each other over the oxide insulating layer; a source electrode layer and a drain electrode layer over the intermediate layers; an oxide semiconductor layer that is electrically connected to the source electrode layer and the drain electrode layer and is in contact with the oxide insulating layer; a gate insulating film over the source electrode layer, the drain electrode layer, and the oxide semiconductor layer; and a gate electrode layer that is over the gate insulating film and overlaps with the source electrode layer, the drain electrode layer, and the oxide semiconductor layer.

Abstract: A semiconductor device in which parasitic capacitance is reduced is provided. A first oxide insulating layer and a first oxide semiconductor layer are sequentially formed over a first insulating layer. A first conductive layer is formed over the first oxide semiconductor layer and etched to form a second conductive layer. The first oxide insulating layer and the first oxide semiconductor layer are etched with the second conductive layer as a mask to form a second oxide insulating layer and a second oxide semiconductor layer. A planarized insulating layer is formed over the first insulating layer and the second conductive layer. A second insulating layer, a source electrode layer, and a drain electrode layer are formed by etching the planarized insulating layer and the second conductive layer. A third oxide insulating layer, a gate insulating layer, and a gate electrode layer are formed over the second oxide semiconductor layer.

Abstract: To provide a semiconductor device having a structure capable of suppressing deterioration of its electrical characteristics which becomes apparent with miniaturization. The semiconductor device includes a first oxide semiconductor film over an insulating surface; a second oxide semiconductor film over the first oxide semiconductor film; a source electrode and a drain electrode in contact with the second oxide semiconductor film; a third oxide semiconductor film over the second oxide semiconductor film, the source electrode, and the drain electrode; a gate insulating film over the third oxide semiconductor film; and a gate electrode over the gate insulating film. A first interface between the gate electrode and the gate insulating film has a region closer to the insulating surface than a second interface between the first oxide semiconductor film and the second oxide semiconductor film.

Abstract: In a processing method of a stacked-layer film in which a metal film is provided on an oxide insulating film, plasma containing an oxygen ion is generated by applying high-frequency power with power density greater than or equal to 0.59 W/cm2 and less than or equal to 1.18 W/cm2 to the stacked-layer film side under an atmosphere containing oxygen in which pressure is greater than or equal to 5 Pa and less than or equal to 15 Pa, the metal film is oxidized by the oxygen ion, and an oxide insulating film containing excess oxygen is formed by supplying oxygen to the oxide insulating film.

Abstract: A semiconductor device with favorable electrical characteristics is provided. The semiconductor device includes an insulating layer, a semiconductor layer over the insulating layer, a source electrode layer and a drain electrode layer electrically connected to the semiconductor layer, a gate insulating film over the semiconductor layer, the source electrode layer, and the drain electrode layer, and a gate electrode layer overlapping with part of the semiconductor layer, part of the source electrode layer, and part of the drain electrode layer with the gate insulating film therebetween. A cross section of the semiconductor layer in the channel width direction is substantially triangular or substantially trapezoidal. The effective channel width is shorter than that for a rectangular cross section.

Abstract: To provide a semiconductor device having a structure with which the device can be easily manufactured even if the size is decreased and which can suppress a decrease in electrical characteristics caused by the decrease in the size, and a manufacturing method thereof. A source electrode layer and a drain electrode layer are formed on an upper surface of an oxide semiconductor layer. A side surface of the oxide semiconductor layer and a side surface of the source electrode layer are provided on the same surface and are electrically connected to a first wiring. Further, a side surface of the oxide semiconductor layer and a side surface of the drain electrode layer are provided on the same surface and are electrically connected to a second wiring.

Abstract: A semiconductor device that operates at high speed. A semiconductor device with favorable switching characteristics. A highly integrated semiconductor device. A miniaturized semiconductor device. The semiconductor device is formed by: fainting a semiconductor film including an opening, on an insulating surface; forming a conductive film over the semiconductor film and in the opening, and removing the conductive film over the semiconductor film to form a conductive pillar in the opening; forming an island-shaped mask over the conductive pillar and the semiconductor film; etching the conductive pillar and the semiconductor film using the mask to form a first electrode and a first semiconductor; forming a gate insulating film on a top surface and a side surface of the first semiconductor; and forming a gate electrode that is in contact with a top surface of the gate insulating film and faces the top surface and the side surface of the first semiconductor.

Abstract: A semiconductor device that operates at high speed. A semiconductor device with favorable switching characteristics. A highly integrated semiconductor device. A miniaturized semiconductor device. The semiconductor device is formed by: forming a semiconductor film including an opening, on an insulating surface; forming a conductive film over the semiconductor film and in the opening, and removing the conductive film over the semiconductor film to form a conductive pillar in the opening; forming an island-shaped mask over the conductive pillar and the semiconductor film; etching the conductive pillar and the semiconductor film using the mask to form a first electrode and a first semiconductor; forming a gate insulating film on a top surface and a side surface of the first semiconductor; and forming a gate electrode that is in contact with a top surface of the gate insulating film and faces the top surface and the side surface of the first semiconductor.

Abstract: A minute transistor and the method of manufacturing the minute transistor. A source electrode layer and a drain electrode layer are each formed in a corresponding opening formed in an insulating layer covering a semiconductor layer. The opening of the source electrode layer and the opening of the drain electrode layer are formed separately in two distinct steps. The source electrode layer and the drain electrode layer are formed by depositing a conductive layer over the insulating layer and in the openings, and subsequently removing the part located over the insulating layer by polishing. This manufacturing method allows for the source electrode later and the drain electrode layer to be formed close to each other and close to a channel forming region of the semiconductor layer. Such a structure leads to a transistor having high electrical characteristics and a high manufacturing yield even in the case of a minute structure.

Abstract: A semiconductor device with a structure in which an increase in the number of oxygen vacancies in an oxide semiconductor layer can be suppressed and a method for manufacturing the semiconductor device are provided. The semiconductor device includes an oxide insulating layer; intermediate layers apart from each other over the oxide insulating layer; a source electrode layer and a drain electrode layer over the intermediate layers; an oxide semiconductor layer that is electrically connected to the source electrode layer and the drain electrode layer and is in contact with the oxide insulating layer; a gate insulating film over the source electrode layer, the drain electrode layer, and the oxide semiconductor layer; and a gate electrode layer that is over the gate insulating film and overlaps with the source electrode layer, the drain electrode layer, and the oxide semiconductor layer.

Abstract: The semiconductor device includes a first insulating layer; a first oxide insulating layer over the first insulating layer; an oxide semiconductor layer over the first oxide insulating layer; a source electrode layer and a drain electrode layer over the oxide semiconductor layer; a second oxide insulating layer over the oxide semiconductor layer, the source electrode layer, and the drain electrode layer; a gate insulating layer over the second oxide insulating layer; a gate electrode layer over the gate insulating layer; a second insulating layer over the first insulating layer, the source electrode layer, the drain electrode layer, the second oxide insulating layer, the gate insulating layer, and the gate electrode layer; and a third insulating layer over the first insulating layer, the source electrode layer, the drain electrode layer, and the second insulating layer.

Abstract: To provide a semiconductor device having a structure capable of suppressing deterioration of its electrical characteristics which becomes apparent with miniaturization. The semiconductor device includes a first oxide semiconductor film over an insulating surface; a second oxide semiconductor film over the first oxide semiconductor film; a source electrode and a drain electrode in contact with the second oxide semiconductor film; a third oxide semiconductor film over the second oxide semiconductor film, the source electrode, and the drain electrode; a gate insulating film over the third oxide semiconductor film; and a gate electrode over the gate insulating film. A first interface between the gate electrode and the gate insulating film has a region closer to the insulating surface than a second interface between the first oxide semiconductor film and the second oxide semiconductor film.

Abstract: A miniaturized transistor having high electric characteristics is provided with high yield. In a semiconductor device including the transistor, high performance, high reliability, and high productivity are achieved. In a semiconductor device including a transistor in which an oxide semiconductor film, a gate insulating film, and a gate electrode layer on side surfaces of which sidewall insulating layers are provided are stacked in this order, source and drain electrode layers are provided in contact with the oxide semiconductor film and the sidewall insulating layers. In a process for manufacturing the semiconductor device, a conductive film and an interlayer insulating film are stacked to cover the oxide semiconductor film, the sidewall insulating layers, and the gate electrode layer, and the interlayer insulating film and the conductive film over the gate electrode layer are removed by a chemical mechanical polishing method, so that the source and drain electrode layers are formed.

Abstract: To provide a semiconductor device having a structure with which the device can be easily manufactured even if the size is decreased and which can suppress a decrease in electrical characteristics caused by the decrease in the size, and a manufacturing method thereof. A source electrode layer and a drain electrode layer are formed on an upper surface of an oxide semiconductor layer. A side surface of the oxide semiconductor layer and a side surface of the source electrode layer are provided on the same surface and are electrically connected to a first wiring. Further, a side surface of the oxide semiconductor layer and a side surface of the drain electrode layer are provided on the same surface and are electrically connected to a second wiring.