Abstract: A semiconductor device with favorable electrical characteristics is to be provided. A highly reliable semiconductor device is to be provided. A semiconductor device with lower power consumption is to be provided. The semiconductor device includes a gate electrode, a first insulating layer over the gate electrode, a metal oxide layer over the first insulating layer, a pair of electrodes over the metal oxide layer, and a second insulating layer over the pair of electrodes. The first insulating layer includes a first region and a second region. The first region has a region being in contact with the metal oxide layer and containing more oxygen than the second region. The second region has a region containing more nitrogen than the first region. The metal oxide layer has at least a concentration gradient of oxygen in a thickness direction, and the concentration gradient becomes high on a first region side and on a second region side.

Abstract: A semiconductor device with favorable electrical characteristics is provided. A highly reliable semiconductor device is provided. A semiconductor device with stable electrical characteristics is provided. A semiconductor device includes a first insulating layer, a second insulating layer, a semiconductor layer, and a first conductive layer. The semiconductor layer, the second insulating layer, and the first conductive layer are stacked in this order over the first insulating layer. The second insulating layer has a stacked-layer structure in which a first insulating film, a second insulating film, and a third insulating film are stacked in this order. The first insulating film, the second insulating film, and the third insulating film each contain an oxide. The first insulating film includes a portion in contact with the semiconductor layer. The semiconductor layer contains indium, gallium, and oxygen and includes a region with an indium content percentage higher than a gallium content percentage.

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: The field-effect mobility and reliability of a transistor including an oxide semiconductor film are improved. A semiconductor layer of a transistor is formed using a composite oxide semiconductor in which a first region and a second region are mixed. The first region includes a plurality of first clusters containing one or more of indium, zinc, and oxygen as a main component. The second region includes a plurality of second clusters containing one or more of indium, an element M (M represents Al, Ga, Y, or Sn), zinc, and oxygen. The first region includes a portion in which the plurality of first clusters are connected to each other. The second region includes a portion in which the plurality of second clusters are connected to each other.

Abstract: A semiconductor device with favorable electrical characteristics is provided. A semiconductor device with stable electrical characteristics is provided. A highly reliable semiconductor device is provided. A semiconductor layer is formed, a gate insulating layer is formed over the semiconductor layer, a metal oxide layer is formed over the gate insulating layer, and a gate electrode which overlaps with part of the semiconductor layer is formed over the metal oxide layer. Then, a first element is supplied through the metal oxide layer and the gate insulating layer to a region of the semiconductor layer that does not overlap with the gate electrode. Examples of the first element include phosphorus, boron, magnesium, aluminum, and silicon. The metal oxide layer may be processed after the first element is supplied to the semiconductor layer.

Abstract: A semiconductor device with favorable electrical characteristics is to be provided. A highly reliable semiconductor device is to be provided. A semiconductor device with lower power consumption is to be provided. The semiconductor device includes a gate electrode, a first insulating layer over the gate electrode, a metal oxide layer over the first insulating layer, a pair of electrodes over the metal oxide layer, and a second insulating layer over the pair of electrodes. The first insulating layer includes a first region and a second region. The first region has a region being in contact with the metal oxide layer and containing more oxygen than the second region. The second region has a region containing more nitrogen than the first region. The metal oxide layer has at least a concentration gradient of oxygen in a thickness direction, and the concentration gradient becomes high on a first region side and on a second region side.

Abstract: A semiconductor device which has favorable electrical characteristics is provided. A method for manufacturing a semiconductor device with high productivity is provided. A method for manufacturing a semiconductor device with a high yield is provided.

Abstract: A semiconductor device with favorable electrical characteristics is provided. A source electrode and a drain electrode of a channel-etched transistor are each made to have a stacked-layer structure including a first conductive layer and a second conductive layer. A silicide that contains a metal element contained in the second conductive layer and nitrogen is formed to be in contact with a top surface and a side surface of the second conductive layer. Before etching of the first conductive layer, the silicide is formed by exposing the second conductive layer to an atmosphere containing silane, and plasma treatment is performed in a nitrogen atmosphere without exposure to the air.

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 liquid crystal display device with a high aperture ratio is provided. A liquid crystal display device with low power consumption is provided. A display device includes a transistor and a capacitor. The transistor includes a first insulating layer, a first semiconductor layer in contact with the first insulating layer, a second insulating layer in contact with the first semiconductor layer, and a first conductive layer electrically connected to the first semiconductor layer via an opening portion provided in the second insulating layer. The capacitor includes a second conductive layer in contact with the first insulating layer, the second insulating layer in contact with the second conductive layer, and the first conductive layer in contact with the second insulating layer. The second conductive layer includes a composition similar to that of the first semiconductor layer. The first conductive layer and the second conductive layer are configured to transmit visible light.

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: The field-effect mobility and reliability of a transistor including an oxide semiconductor film are improved. A semiconductor layer of a transistor is formed using a composite oxide semiconductor in which a first region and a second region are mixed. The first region includes a plurality of first clusters containing one or more of indium, zinc, and oxygen as a main component. The second region includes a plurality of second clusters containing one or more of indium, an element M (M represents Al, Ga, Y, or Sn), zinc, and oxygen. The first region includes a portion in which the plurality of first clusters are connected to each other. The second region includes a portion in which the plurality of second clusters are connected to each other.

Abstract: A semiconductor device with favorable electrical characteristics is provided. A semiconductor device having stable electrical characteristics is provided. A highly reliable semiconductor device is provided. The semiconductor device includes a semiconductor layer, a first insulating layer, a second insulating layer, and a conductive layer. The first insulating layer is in contact with part of the top surface of the semiconductor layer, the conductive layer is positioned over the first insulating layer, and the second insulating layer is positioned over the semiconductor layer. The semiconductor layer contains a metal oxide and includes a first region overlapping with the conductive layer and a second region not overlapping with the conductive layer. The second region is in contact with the second insulating layer. The second insulating layer contains oxygen and a first element. The first element is one or more of phosphorus, boron, magnesium, aluminum, and silicon.

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 display device includes a liquid crystal element, a transistor, a scan line, and a signal line. The liquid crystal element includes a pixel electrode, a liquid crystal layer, and a common electrode. The scan line and the signal line are each electrically connected to the transistor. The scan line and the signal line each include a metal layer. The transistor is electrically connected to the pixel electrode. A semiconductor layer of the transistor includes a stack of a first metal oxide layer and a second metal oxide layer. The first metal oxide layer includes a region with lower crystallinity than the second metal oxide layer. The transistor includes a first region connected to the pixel electrode. The pixel electrode, the common electrode, and the first region are each configured to transmit visible light. Visible light passes through the first region and the liquid crystal element and exits from the display device.

Abstract: A semiconductor device is fabricated by a method including the following steps: a first step of forming a semiconductor film containing a metal oxide over an insulating layer; a second step of forming a conductive film over the semiconductor film; a third step of forming a first resist mask over the conductive film and etching the conductive film to form a first conductive layer and to expose a top surface of the semiconductor film that is not covered with the first conductive layer; and a fourth step of forming a second resist mask that covers a top surface and a side surface of the first conductive layer and part of the top surface of the semiconductor film and etching the semiconductor film to form a semiconductor layer and to expose a top surface of the insulating layer that is not covered with the semiconductor layer.

Abstract: A semiconductor device comprising a pixel portion comprising a capacitor and a transistor is provided. The capacitor comprises a first oxide semiconductor film and a transparent conductive material. The transistor comprises a second oxide semiconductor film, a source electrode, and a drain electrode. The transistor is electrically connected to the capacitor. The capacitor is provided to overlap with a first opening portion in an insulating film and a second opening portion in an organic resin film. The transparent conductive material comprises a region over the organic resin film. The second oxide semiconductor film comprises a channel formation region and a first region outside the channel formation region. Each of a carrier density of the first oxide semiconductor film and a carrier density of the first region is higher than a carrier density of the channel formation region.

Abstract: A semiconductor device with favorable electrical characteristics is provided. A semiconductor device with stable electrical characteristics is provided. A highly reliable display device is provided. The semiconductor device is fabricated by a method that includes a first step of forming a semiconductor layer containing a metal oxide, a second step of forming a conductive film over the semiconductor layer, a third step of etching the conductive film such that the conductive film is divided over the semiconductor layer and a portion of the semiconductor layer is uncovered, and a fourth step of performing first treatment on the conductive film and the portion of the semiconductor layer. The conductive film contains copper, silver, gold, or aluminum. The first treatment is plasma treatment in an atmosphere containing a mixed gas of a first gas containing an oxygen element and a second gas containing a hydrogen element.

Abstract: A liquid crystal display device with a high aperture ratio is provided. A liquid crystal display device with low power consumption is provided. A display device includes a transistor and a capacitor. The transistor includes a first insulating layer, a first semiconductor layer in contact with the first insulating layer, a second insulating layer in contact with the first semiconductor layer, and a first conductive layer electrically connected to the first semiconductor layer via an opening portion provided in the second insulating layer. The capacitor includes a second conductive layer in contact with the first insulating layer, the second insulating layer in contact with the second conductive layer, and the first conductive layer in contact with the second insulating layer. The second conductive layer includes a composition similar to that of the first semiconductor layer. The first conductive layer and the second conductive layer are configured to transmit visible light.

Abstract: A semiconductor device including an oxide semiconductor film that includes a transistor with excellent electrical characteristics is provided. It is a semiconductor device including a transistor. The transistor includes a gate electrode, a first insulating film, an oxide semiconductor film, a source electrode, a drain electrode, and a second insulating film. The source electrode and the drain electrode each include a first conductive film, a second conductive film over and in contact with the first conductive film, and a third conductive film over and in contact with the second conductive film. The second conductive film contains copper, the first conductive film and the third conductive film include a material that inhibits diffusion of copper, and an end portion of the second conductive film includes a region containing copper and silicon.