Abstract: An imaging device with excellent imaging performance is provided. An imaging device that easily performs imaging under a low illuminance condition is provided. A low power consumption imaging device is provided. An imaging device with small variations in characteristics between its pixels is provided. A highly integrated imaging device is provided. A photoelectric conversion element includes a first electrode, and a first layer, a second layer, and a third layer. The first layer is provided between the first electrode and the third layer. The second layer is provided between the first layer and the third layer. The first layer contains selenium. The second layer contains a metal oxide. The third layer contains a metal oxide and also contains at least one of a rare gas atom, phosphorus, and boron. The selenium may be crystalline selenium. The second layer may be a layer of an In—Ga—Zn oxide including c-axis-aligned crystals.

Abstract: Provided is a semiconductor device including a transistor having excellent electrical characteristics (e.g., on-state current, field-effect mobility, or frequency characteristics) or a semiconductor device including a transistor with high reliability. In the channel width direction of a channel-etched transistor in which an oxide semiconductor film is between first and second gate electrodes, the first and second gate electrodes are connected to each other through an opening portion in first and second gate insulating films. In addition, the first and second gate electrodes surround the oxide semiconductor film in a cross-section in the channel width direction, with the first gate insulating film provided between the first gate electrode and the oxide semiconductor film and the second gate insulating film provided between the second gate electrode and the oxide semiconductor film. Furthermore, the channel length of the transistor is 0.5 ?m or longer and 6.5 ?m or shorter.

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 highly reliable semiconductor device is provided. The semiconductor device includes a gate electrode, a gate insulating film over the gate electrode, a semiconductor film overlapping with the gate electrode with the gate insulating film positioned therebetween, a source electrode and a drain electrode that are in contact with the semiconductor film, and an oxide film over the semiconductor film, the source electrode, and the drain electrode. An end portion of the semiconductor film is spaced from an end portion of the source electrode or the drain electrode in a region overlapping with the semiconductor film in a channel width direction. The semiconductor film and the oxide film each include a metal oxide including In, Ga, and Zn. The oxide film has an atomic ratio where the atomic percent of In is lower than the atomic percent of In in the atomic ratio of the semiconductor film.

Abstract: A transistor whose channel is formed in a semiconductor having dielectric anisotropy is provided. A transistor having a small subthreshold swing value is provided. A transistor having normally-off electrical characteristics is provided. A transistor having a low leakage current in an off state is provided. A semiconductor device includes an insulator, a semiconductor, and a conductor. In the semiconductor device, the semiconductor includes a region overlapping with the conductor with the insulator positioned therebetween, and a dielectric constant of the region in a direction perpendicular to a top surface of the region is higher than a dielectric constant of the region in a direction parallel to the top surface.

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: A semiconductor device includes a first insulating layer over a substrate, a first metal oxide layer over the first insulating layer, an oxide semiconductor layer over the first metal oxide layer, a second metal oxide layer over the oxide semiconductor layer, a gate insulating layer over the second metal oxide layer, a second insulating layer over the second metal oxide layer, and a gate electrode layer over the gate insulating layer. The gate insulating layer includes a region in contact with a side surface of the gate electrode layer. The second insulating layer includes a region in contact with the gate insulating layer. The oxide semiconductor layer includes first to third regions. The first region includes a region overlapping with the gate electrode layer. The second region, which is between the first and third regions, includes a region overlapping with the gate insulating layer or the second insulating layer.

Abstract: A transistor having favorable electrical characteristics. A transistor suitable for miniaturization. A transistor having a high switching speed. One embodiment of the present invention is a semiconductor device that includes a transistor. The transistor includes an oxide semiconductor, a gate electrode, and a gate insulator. The oxide semiconductor includes a first region in which the oxide semiconductor and the gate electrode overlap with each other with the gate insulator positioned therebetween. The transistor has a threshold voltage higher than 0 V and a switching speed lower than 100 nanoseconds.

Abstract: A multilayer inductor providing improved DC superposition characteristics by a permanent magnet that emits a bias magnetic flux, and having a low-loss material as a magnetic body to improve converter conversion efficiency. The multilayer inductor has a plurality of laminated electrically insulating magnetic layers; and laminated conductive patterns, each of the conductive patterns being connected in sequence in the lamination direction forming a spiral coil inside the magnetic layer. An magnetized annular permanent magnet layer emits a magnetic flux whose direction is opposite that of a magnetic flux excited by the coil is between an outer peripheral edge of the inductor and an outer peripheral edge of the coil so as not to overlap an inner peripheral part of the magnet layer with the conductive patterns and so as to block a space between the conductive patterns and the magnet layer, in axial view of the coil.

Abstract: A semiconductor device includes a transistor including a gate electrode over a substrate, a gate insulating film covering the gate electrode, a multilayer film overlapping with the gate electrode with the gate insulating film provided therebetween, and a pair of electrodes in contact with the multilayer film, and an oxide insulating film covering the transistor. The multilayer film includes an oxide semiconductor film and an oxide film containing In or Ga, the oxide insulating film contains more oxygen than that in the stoichiometric composition, and in the transistor, by a bias-temperature stress test, threshold voltage does not change or the amount of the change in a positive direction or a negative direction is less than or equal to 1.0 V, preferably less than or equal to 0.5 V.

Abstract: A selection operation is performed for individual memory cells. A device includes a first memory cell and a second memory cell provided in the same row as the first memory cell, each of which includes a field-effect transistor having a first gate and a second gate. The field-effect transistor controls at least data writing and data holding in the memory cell by being turned on or off. The device further includes a row selection line electrically connected to the first gates of the field-effect transistors included in the first memory cell and the second memory cell, a first column selection line electrically connected to the second gate of the field-effect transistor included in the first memory cell, and a second column selection line electrically connected to the second gate of the field-effect transistor included in the second memory cell.

Abstract: The semiconductor device includes a transistor including an oxide semiconductor film having a channel formation region, a gate insulating film, and a gate electrode layer. In the transistor, the channel length is small (5 nm or more and less than 60 nm, preferably 10 nm or more and 40 nm or less), and the thickness of the gate insulating film is large (equivalent oxide thickness which is obtained by converting into a thickness of silicon oxide containing nitrogen is 5 nm or more and 50 nm or less, preferably 10 nm or more and 40 nm or less). Alternatively, the channel length is small (5 nm or more and less than 60 nm, preferably 10 nm or more and 40 nm or less), and the resistivity of the source region and the drain region is 1.9×10?5 ?·m or more and 4.8×10?3 ?·m or less.

Abstract: Provided is a semiconductor device including a transistor having excellent electrical characteristics (e.g., on-state current, field-effect mobility, or frequency characteristics) or a semiconductor device including a transistor with high reliability. In the channel width direction of a channel-etched transistor in which an oxide semiconductor film is between first and second gate electrodes, the first and second gate electrodes are connected to each other through an opening portion in first and second gate insulating films. In addition, the first and second gate electrodes surround the oxide semiconductor film in a cross-section in the channel width direction, with the first gate insulating film provided between the first gate electrode and the oxide semiconductor film and the second gate insulating film provided between the second gate electrode and the oxide semiconductor film. Furthermore, the channel length of the transistor is 0.5 ?m or longer and 6.5 ?m or shorter.

Abstract: A semiconductor device includes a first conductor, a second conductor, a first insulator, a second insulator, a third insulator, a semiconductor, and an electron trap layer. The semiconductor includes a channel formation region. The electron trap layer overlaps with the channel formation region with the second insulator interposed therebetween. The first conductor overlaps with the channel formation region with the first insulator interposed therebetween. The second conductor overlaps with the electron trap layer with the third insulator interposed therebetween. The second conductor does not overlap with the channel formation region.

Abstract: The following semiconductor device provides high reliability and a narrower frame width. The semiconductor device includes a driver circuit and a pixel portion. The driver circuit has a first transistor including a first gate and a second gate electrically connected to each other with a semiconductor film sandwiched therebetween, and a second transistor electrically connected to the first transistor. The pixel portion includes a third transistor, a liquid crystal element, and a capacitor. The liquid crystal element includes a first transparent conductive film electrically connected to the third transistor, a second conductive film, and a liquid crystal layer. The capacitor includes the first conductive film, a third transparent conductive film, and a nitride insulating film. The nitride insulating film is positioned between the first transparent conductive film and the third transparent conductive film, and positioned between the semiconductor film and the second gate of the first transistor.

Abstract: A semiconductor device in which parasitic capacitance is reduced is provided. A first insulating layer is deposited over a substrate. A first oxide insulating layer and an oxide semiconductor layer are deposited over the first insulating layer. A second oxide insulating layer is deposited over the oxide semiconductor layer and the first insulating layer. A second insulating layer and a first conductive layer are deposited over the second oxide insulating layer. A gate electrode layer, a gate insulating layer, and a third oxide insulating layer are formed by etching. A sidewall insulating layer including a region in contact with a side surface of the gate electrode layer is formed. A second conductive layer is deposited over the gate electrode layer, the sidewall insulating layer, the oxide semiconductor layer, and the first insulating layer. A third conductive layer is deposited over the second conductive layer. A low-resistance region is formed in the oxide semiconductor layer by performing heat treatment.

Abstract: A miniaturized transistor with reduced parasitic capacitance and highly stable electrical characteristics is provided. High performance and high reliability of a semiconductor device including the transistor is achieved. A first conductor is formed over a substrate, a first insulator is formed over the first conductor, a layer that retains fixed charges is formed over the first insulator, a second insulator is formed over the layer that retains fixed charges, and a transistor is formed over the second insulator. Threshold voltage Vth is controlled by appropriate adjustment of the thicknesses of the first insulator, the second insulator, and the layer that retains fixed charges.

Abstract: A first source electrode is formed in contact with a semiconductor layer; a first drain electrode is formed in contact with the semiconductor layer; a second source electrode which extends beyond an end portion of the first source electrode to be in contact with the semiconductor layer is formed; a second drain electrode which extends beyond an end portion of the first drain electrode to be in contact with the semiconductor layer is formed; a first sidewall is formed in contact with a side surface of the second source electrode and the semiconductor layer; a second sidewall is formed in contact with a side surface of the second drain electrode and the semiconductor layer; and a gate electrode is formed to overlap the first sidewall, the second sidewall, and the semiconductor layer with a gate insulating layer provided therebetween.

Abstract: A semiconductor device that includes transistors with different threshold voltages is provided. Alternatively, a semiconductor device including a plurality of kinds of circuits and transistors whose electrical characteristics are different between the circuits is provided. The semiconductor device includes a first transistor and a second transistor. The first transistor includes an oxide semiconductor, a conductor, a first insulator, a second insulator, and a third insulator. The conductor has a region where the conductor and the oxide semiconductor overlap with each other. The first insulator is positioned between the conductor and the oxide semiconductor. The second insulator is positioned between the conductor and the first insulator. The third insulator is positioned between the conductor and the second insulator. The second insulator has a negatively charged region.

Abstract: An imaging device with excellent imaging performance is provided. An imaging device that easily performs imaging under a low illuminance condition is provided. A low power consumption imaging device is provided. An imaging device with small variations in characteristics between its pixels is provided. A highly integrated imaging device is provided. A photoelectric conversion element includes a first electrode, and a first layer, a second layer, and a third layer. The first layer is provided between the first electrode and the third layer. The second layer is provided between the first layer and the third layer. The first layer contains selenium. The second layer contains a metal oxide. The third layer contains a metal oxide and also contains at least one of a rare gas atom, phosphorus, and boron. The selenium may be crystalline selenium. The second layer may be a layer of an In—Ga—Zn oxide including c-axis-aligned crystals.