In a semiconductor device including a transistor including an oxide semiconductor film and a protective film over the transistor, an oxide insulating film containing oxygen in excess of the stoichiometric composition is formed as the protective film under the following conditions: a substrate placed in a treatment chamber evacuated to a vacuum level is held at a temperature higher than or equal to 180° C. and lower than or equal to 260° C.; a source gas is introduced into the treatment chamber so that the pressure in the treatment chamber is set to be higher than or equal to 100 Pa and lower than or equal to 250 Pa; and a high-frequency power higher than or equal to 0.17 W/cm.sup.2 and lower than or equal to 0.5 W/cm.sup.2 is supplied to an electrode provided in the treatment chamber.

To improve field-effect mobility and reliability of a transistor including an oxide semiconductor film. A semiconductor device includes an oxide semiconductor film, a gate electrode, an insulating film over the gate electrode, the oxide semiconductor film over the insulating film, and a pair of electrodes over the oxide semiconductor film. The oxide semiconductor film includes a first oxide semiconductor film and a second oxide semiconductor film over the first oxide semiconductor film. The first oxide semiconductor film and the second oxide semiconductor film, include the same element. The first oxide semiconductor film includes a region having lower crystallinity than the second oxide semiconductor film.

A display device may include a first pixel coupled to an emission control line, and an emission control stage for selectively coupling the emission control line to a first or second supply voltage line. The emission control stage may include: a first emission control transistor including a first electrode coupled to the first supply voltage line, a second electrode coupled to the emission control line, and a main gate electrode coupled to a first node; a second emission control transistor including a first electrode coupled to the emission control line, a second electrode coupled to the second supply voltage line, and a main gate electrode coupled to a second node; and a third emission control transistor including a first electrode coupled to the first supply voltage line, a second electrode coupled to the first node, a main gate electrode coupled to the second node, and a sub-gate electrode.

An electronic device including a flexible display panel is provided. The electronic device includes a display panel, a first component, a movable module, and a housing. The housing includes a first movable portion, a second component, and a third component. The third component includes a first space where the first component is stored. The display panel includes a flexible display portion. The display portion includes a first region, a second region, and a third region. The first region is fixed to the second component. The second region is fixed to the first component stored in the third component. The movable module has a function of holding a first angle that is formed between the second component and the third component by the first movable portion. The third region positioned between the first region and the second region has a function of forming a curved surface according to the first angle. The first component slides in the first space according to the first angle.

Provided are techniques for generating fully depleted silicon on insulator (SOI) transistor with a ferroelectric layer. The techniques include forming a first multi-layer wafer comprising a semiconductor layer and a buried oxide layer, wherein the semiconductor layer is formed over the buried oxide layer. The techniques also including forming a second multi-layer wafer comprising the ferroelectric layer, and bonding the first multi-layer wafer to the second multi-layer wafer, wherein the bonding comprises a coupling between the buried oxide layer and the second multi-layer wafer.

An active matrix substrate includes a first TFT and a second TFT, in which the first TFT includes a first oxide semiconductor layer and a first gate electrode arranged on a part of the first oxide semiconductor layer with a first gate insulating layer interposed therebetween, the first gate insulating layer has a layered structure including a first insulating film and a second insulating film arranged on the first insulating film, the second TFT includes a second oxide semiconductor layer having a higher mobility than the first oxide semiconductor layer and a second gate electrode arranged on a part of the second oxide semiconductor layer with a second gate insulating layer interposed therebetween, and the second gate insulating layer includes the second insulating film and does not include the first insulating film, and the second TFT further includes a lower insulating layer including the first insulating film arranged between the second oxide semiconductor layer and a substrate.

A semiconductor device with a small variation in characteristics is provided. A semiconductor device includes an oxide, a first conductor and a second conductor over the oxide, a first insulator over the first conductor, a second insulator over the second conductor, a third insulator over the first insulator and the second insulator, a fourth insulator over the third insulator, a fifth insulator that is over the oxide and placed between the first conductor and the second conductor, a sixth insulator over the fifth insulator, and a third conductor over the sixth insulator. The third conductor includes a region overlapping the oxide. The fifth insulator includes a region in contact with the oxide, the first conductor, the second conductor, and each of the first insulator to the fourth insulator. The fifth insulator contains nitrogen, oxygen, and silicon.

A semiconductor device with a small variation in characteristics is provided. The semiconductor device includes a first insulator; a second insulator having an opening over the first insulator; a third insulator that has a first depressed portion and is provided inside the opening; a first oxide that has a second depressed portion and is provided inside the first depressed portion; a second oxide provided inside the second depressed portion; a first conductor and a second conductor that are electrically connected to the second oxide and are apart from each other; a fourth insulator over the second oxide; and a third conductor including a region overlapping with the second oxide with the fourth insulator therebetween. The second oxide includes a first region, a second region, and a third region sandwiched between the first region and the second region in a top view. The first conductor includes a region overlapping with the first region and the second insulator. The second conductor includes a region overlapping with the second region and the second insulator. The third conductor includes a region overlapping with the third region.

As a display device has a higher definition, the number of pixels, gate lines, and signal lines are increased. When the number of the gate lines and the signal lines are increased, a problem of high manufacturing cost, because it is difficult to mount an IC chip including a driver circuit for driving of the gate and signal lines by bonding or the like. A pixel portion and a driver circuit for driving the pixel portion are provided over the same substrate, and at least part of the driver circuit includes a thin film transistor using an oxide semiconductor interposed between gate electrodes provided above and below the oxide semiconductor. Therefore, when the pixel portion and the driver portion are provided over the same substrate, manufacturing cost can be reduced.

To provide a miniaturized semiconductor device with low power consumption. A method for manufacturing a wiring layer includes the following steps: forming a second insulator over a first insulator; forming a third insulator over the second insulator; forming an opening in the third insulator so that it reaches the second insulator; forming a first conductor over the third insulator and in the opening; forming a second conductor over the first conductor; and after forming the second conductor, performing polishing treatment to remove portions of the first and second conductors above a top surface of the third insulator. An end of the first conductor is at a level lower than or equal to the top level of the opening. The top surface of the second conductor is at a level lower than or equal to that of the end of the first conductor.