Abstract: A semiconductor device includes a first conductor; a first insulator thereover; a first oxide thereover; a second oxide thereover; a second conductor and a third conductor that are separate from each other thereover; a third oxide over the first insulator, the second oxide, the second conductor, and the third conductor; a second insulator thereover; a fourth conductor thereover; and a third insulator over the first insulator, the second insulator, and the fourth conductor. The second oxide includes a region where the energy of the conduction band minimum of an energy band is low and a region where the energy of the conduction band minimum of the energy band is high. The energy of the conduction band minimum of the third oxide is higher than that of the region of the second oxide where the energy of the conduction band minimum is low. Side surfaces of the first oxide and the second oxide are covered with the third oxide.

Abstract: To provide a transistor having a high on-state current. A semiconductor device includes a first insulator containing excess oxygen, a first oxide semiconductor over the first insulator, a second oxide semiconductor over the first oxide semiconductor, a first conductor and a second conductor which are over the second oxide semiconductor and are separated from each other, a third oxide semiconductor in contact with side surfaces of the first oxide semiconductor, a top surface and side surfaces of the second oxide semiconductor, a top surface of the first conductor, and a top surface of the second conductor, a second insulator over the third oxide semiconductor, and a third conductor facing a top surface and side surfaces of the second oxide semiconductor with the second insulator and the third oxide semiconductor therebetween. The first oxide semiconductor has a higher oxygen-transmitting property than the third oxide semiconductor.

Abstract: A high-performance semiconductor device is provided. The semiconductor device includes a transistor, an insulating film over the transistor, an electrode, and a metal oxide over the insulating film. The transistor includes a first gate electrode, a first gate insulating film over the first gate electrode, an oxide over the first gate insulating film, a source electrode and a drain electrode electrically connected to the oxide, a second gate insulating film over the oxide, and a second gate electrode over the second gate insulating film. The electrode includes a region in contact with the insulating film. The first gate insulating film is in contact with the insulating film. The thicknesses of the insulating film over the second gate electrode, the insulating film over the source electrode, and the insulating film over the drain electrode are substantially the same, and the insulating film includes excess oxygen.

Abstract: A highly reliable semiconductor device is provided. The semiconductor device includes a first insulator; a first oxide provided over the first insulator; a second oxide provided over the first oxide; a first conductor and a second conductor provided apart from each other over the second oxide; a third oxide provided over the second oxide, the first conductor, and the second conductor; a second insulating film provided over the third oxide; and a third conductor provided over the second oxide with the third oxide and the second insulating film positioned therebetween. The third oxide contains a metal element and nitrogen, and the metal element is bonded to nitrogen.

Abstract: To provide a semiconductor device including an oxide semiconductor layer with high and stable electrical characteristics, the semiconductor device is manufactured by forming a first insulating layer, forming oxide over the first insulating layer and then removing the oxide n times (n is a natural number), forming an oxide semiconductor layer over the first insulating layer, forming a second insulating layer over the oxide semiconductor layer, and forming a conductive layer over the second insulating layer. Alternatively, the semiconductor device is manufactured by forming the oxide semiconductor layer over the first insulating layer, forming the second insulating layer over the oxide semiconductor layer, forming the oxide over the second insulating layer and then removing the oxide n times (n is a natural number), and forming the conductive layer over the second insulating layer.

Abstract: A semiconductor device having a reduced amount of oxygen vacancy in a channel formation region of an oxide semiconductor is provided. Further, a semiconductor device which includes an oxide semiconductor and has improved electric characteristics is provided. Furthermore, a methods for manufacturing the semiconductor device is provided. An oxide semiconductor film is formed; a conductive film is formed over the oxide semiconductor film at the same time as forming a low-resistance region between the oxide semiconductor film and the conductive film; the conductive film is processed to form a source electrode and a drain electrode; and oxygen is added to the low-resistance region between the source electrode and the drain electrode, so that a channel formation region having a higher resistance than the low-resistance region is formed and a first low-resistance region and a second low-resistance region between which the channel formation region is positioned are formed.

Abstract: A semiconductor device having favorable electrical characteristics is provided. The semiconductor device includes an oxide semiconductor, a first insulator in contact with the oxide semiconductor, and a second insulator in contact with the first insulator. The first insulator includes excess oxygen. The second insulator has a function of trapping or fixing hydrogen. Hydrogen in the oxide semiconductor is bonded to the excess oxygen. The hydrogen bonded to the excess oxygen passes through the first insulator and is trapped or fixed in the second insulator. The excess oxygen bonded to the hydrogen remains in the first insulator as the excess oxygen.

Abstract: A semiconductor device having a reduced amount of oxygen vacancy in a channel formation region of an oxide semiconductor is provided. Further, a semiconductor device which includes an oxide semiconductor and has improved electric characteristics is provided. Furthermore, a methods for manufacturing the semiconductor device is provided. An oxide semiconductor film is formed; a conductive film is formed over the oxide semiconductor film at the same time as forming a low-resistance region between the oxide semiconductor film and the conductive film; the conductive film is processed to form a source electrode and a drain electrode; and oxygen is added to the low-resistance region between the source electrode and the drain electrode, so that a channel formation region having a higher resistance than the low-resistance region is formed and a first low-resistance region and a second low-resistance region between which the channel formation region is positioned are formed.

Abstract: A semiconductor device includes a first conductor; a first insulator thereover; a first oxide thereover; a second oxide thereover; a second conductor and a third conductor that are separate from each other thereover; a third oxide over the first insulator, the second oxide, the second conductor, and the third conductor; a second insulator thereover; a fourth conductor thereover; and a third insulator over the first insulator, the second insulator, and the fourth conductor. The second oxide includes a region where the energy of the conduction band minimum of an energy band is low and a region where the energy of the conduction band minimum of the energy band is high. The energy of the conduction band minimum of the third oxide is higher than that of the region of the second oxide where the energy of the conduction band minimum is low. Side surfaces of the first oxide and the second oxide are covered with the third oxide.

Abstract: A semiconductor device includes a first conductor; a first insulator thereover; a first oxide thereover; a second oxide thereover; a second conductor and a third conductor that are separate from each other thereover; a third oxide over the first insulator, the second oxide, the second conductor, and the third conductor; a second insulator thereover; a fourth conductor thereover; and a third insulator over the first insulator, the second insulator, and the fourth conductor. The second oxide includes a region where the energy of the conduction band minimum of an energy band is low and a region where the energy of the conduction band minimum of the energy band is high. The energy of the conduction band minimum of the third oxide is higher than that of the region of the second oxide where the energy of the conduction band minimum is low. Side surfaces of the first oxide and the second oxide are covered with the third oxide.

Abstract: Provided is a semiconductor device having a structure with which a decrease in electrical characteristics that becomes more significant with miniaturization can be suppressed. The semiconductor device includes a first oxide semiconductor film, a gate electrode overlapping with the first oxide semiconductor film, a first gate insulating film between the first oxide semiconductor film and the gate electrode, and a second gate insulating film between the first gate insulating film and the gate electrode. In the first gate insulating film, a peak appears at a diffraction angle 2? of around 28° by X-ray diffraction. A band gap of the first oxide semiconductor film is smaller than a band gap of the first gate insulating film, and the band gap of the first gate insulating film is smaller than a band gap of the second gate insulating film.

Abstract: To provide a semiconductor device including an oxide semiconductor layer with high and stable electrical characteristics, the semiconductor device is manufactured by forming a first insulating layer, forming oxide over the first insulating layer and then removing the oxide n times (n is a natural number), forming an oxide semiconductor layer over the first insulating layer, forming a second insulating layer over the oxide semiconductor layer, and forming a conductive layer over the second insulating layer. Alternatively, the semiconductor device is manufactured by forming the oxide semiconductor layer over the first insulating layer, forming the second insulating layer over the oxide semiconductor layer, forming the oxide over the second insulating layer and then removing the oxide n times (n is a natural number), and forming the conductive layer over the second insulating layer.

Abstract: To provide a novel oxide semiconductor film. The oxide semiconductor film includes In, M, and Zn. The M is Al, Ga, Y, or Sn. In the case where the proportion of In in the oxide semiconductor film is 4, the proportion of M is greater than or equal to 1.5 and less than or equal to 2.5 and the proportion of Zn is greater than or equal to 2 and less than or equal to 4.

Abstract: A high-performance semiconductor device is provided. The semiconductor device includes a transistor, an insulating film over the transistor, an electrode, and a metal oxide over the insulating film. The transistor includes a first gate electrode, a first gate insulating film over the first gate electrode, an oxide over the first gate insulating film, a source electrode and a drain electrode electrically connected to the oxide, a second gate insulating film over the oxide, and a second gate electrode over the second gate insulating film. The electrode includes a region in contact with the insulating film. The first gate insulating film is in contact with the insulating film. The thicknesses of the insulating film over the second gate electrode, the insulating film over the source electrode, and the insulating film over the drain electrode are substantially the same, and the insulating film includes excess oxygen.

Abstract: To provide a transistor having a high on-state current. A semiconductor device includes a first insulator containing excess oxygen, a first oxide semiconductor over the first insulator, a second oxide semiconductor over the first oxide semiconductor, a first conductor and a second conductor which are over the second oxide semiconductor and are separated from each other, a third oxide semiconductor in contact with side surfaces of the first oxide semiconductor, a top surface and side surfaces of the second oxide semiconductor, a top surface of the first conductor, and a top surface of the second conductor, a second insulator over the third oxide semiconductor, and a third conductor facing a top surface and side surfaces of the second oxide semiconductor with the second insulator and the third oxide semiconductor therebetween. The first oxide semiconductor has a higher oxygen-transmitting property than the third oxide semiconductor.

Abstract: To provide a novel oxide semiconductor film. The oxide semiconductor film includes In, M, and Zn. The M is Al, Ga, Y, or Sn. In the case where the proportion of In in the oxide semiconductor film is 4, the proportion of M is greater than or equal to 1.5 and less than or equal to 2.5 and the proportion of Zn is greater than or equal to 2 and less than or equal to 4.

Abstract: A method of forming an oxide semiconductor includes a step of depositing an oxide semiconductor layer over a substrate by using a sputtering apparatus in which in a target containing indium, an element M (aluminum, gallium, yttrium, or tin), zinc, and oxygen, the substrate which faces a surface of the target, and a magnet unit comprising a first magnet and a second magnet on a rear surface side of the target are provided. In the method, deposition is performed under a condition that a maximum intensity of a horizontal magnetic field is greater than or equal to 350 G and less than or equal to 2000 G in a plane where a vertical distance toward the substrate from a surface of the magnet unit is 10 mm.

Abstract: To provide a transistor having a high on-state current. A semiconductor device includes a first insulator containing excess oxygen, a first oxide semiconductor over the first insulator, a second oxide semiconductor over the first oxide semiconductor, a first conductor and a second conductor which are over the second oxide semiconductor and are separated from each other, a third oxide semiconductor in contact with side surfaces of the first oxide semiconductor, a top surface and side surfaces of the second oxide semiconductor, a top surface of the first conductor, and a top surface of the second conductor, a second insulator over the third oxide semiconductor, and a third conductor facing a top surface and side surfaces of the second oxide semiconductor with the second insulator and the third oxide semiconductor therebetween. The first oxide semiconductor has a higher oxygen-transmitting property than the third oxide semiconductor.

Abstract: The reliability of a semiconductor device is increased by suppression of a variation in electric characteristics of a transistor as much as possible. As a cause of a variation in electric characteristics of a transistor including an oxide semiconductor, the concentration of hydrogen in the oxide semiconductor, the density of oxygen vacancies in the oxide semiconductor, or the like can be given. A source electrode and a drain electrode are formed using a conductive material which is easily bonded to oxygen. A channel formation region is formed using an oxide layer formed by a sputtering method or the like under an atmosphere containing oxygen. Thus, the concentration of hydrogen in a stack, in particular, the concentration of hydrogen in a channel formation region can be reduced.

Abstract: A transistor with stable electrical characteristics is provided. The transistor includes a first insulator over a substrate; first to third oxide insulators over the first insulator; a second insulator over the third oxide insulator; a first conductor over the second insulator; and a third insulator over the first conductor. An energy level of a conduction band minimum of each of the first and second oxide insulators is closer to a vacuum level than that of the oxide semiconductor is. An energy level of a conduction band minimum of the third oxide insulator is closer to the vacuum level than that of the second oxide insulator is. The first insulator contains oxygen. The number of oxygen molecules released from the first insulator measured by thermal desorption spectroscopy is greater than or equal to 1E14 molecules/cm2 and less than or equal to 1E16 molecules/cm2.