A semiconductor device capable of retaining data for a long time is provided. A leakage current path between adjacent memory cells in a memory cell array included in the semiconductor device is blocked without increasing the number of manufacturing steps, so that memory retention characteristics can be improved.

Some embodiments include apparatuses in which one of such apparatus includes a first memory cell including a first transistor having a first channel region coupled between a data line and a conductive region, and a first charge storage structure located between the first data line and the conductive region, and a second transistor having a second channel region coupled to and located between the first data line and the first charge storage structure; a second memory cell including a third transistor having a third channel region coupled between a second data line and the conductive region, and a second charge storage structure located between the second data line and the conductive region, and a fourth transistor having a fourth channel region coupled to and located between the second data line and the second charge storage structure; a conductive line forming a gate of each of the first, second, third, and fourth transistors; and a conductive structure located between the first and second charge storage structures and electrically separated from the conductive region.

Reducing the power consumption of a transistor and stably controlling its threshold value. Providing a transistor comprising a first conductive layer, a first insulating layer and a second insulating layer over the first conductive layer, a semiconductor layer over the first insulating layer, a third insulating layer over the first conductive layer and the semiconductor layer, a second conductive layer over the second insulating layer, and a gate electrode over the third insulating layer. The first conductive layer is in an electrically floating state. The first conductive layer has a region overlapping with the semiconductor layer with the first insulating layer provided therebetween, a region overlapping with the second conductive layer with the second insulating layer provided therebetween, and a region overlapping with the gate electrode with the third insulating layer provided therebetween.

A semiconductor device with low power consumption can be provided. The semiconductor device includes a differential circuit and a latch circuit, the differential circuit includes a transistor including an oxide semiconductor in a channel formation region, and the latch circuit includes a transistor including a single semiconductor or a compound semiconductor in a channel formation region. The differential circuit and the latch circuit include an overlap region.

A semiconductor device of embodiments includes: a first electrode; a second electrode; an oxide semiconductor layer between the first electrode and the second electrode and including a first region surrounded by the first electrode in a plane perpendicular to a first direction from the first electrode toward the second electrode; a gate electrode facing the oxide semiconductor layer; a gate insulating layer; a first insulating layer between the gate electrode and the first electrode; and a second insulating layer between the gate electrode and the second electrode. A first maximum distance between a first portion of the first electrode and a second portion of the first electrode in a second direction in a cross section parallel to the first direction is larger than a minimum distance between a third portion of the first insulating layer and a fourth portion of the first insulating layer in the second direction.

A semiconductor device of embodiments includes: a first electrode; a second electrode; an oxide semiconductor layer between the first electrode and the second electrode; a gate electrode surrounding the oxide semiconductor layer; a gate insulating layer between the gate electrode and the oxide semiconductor layer; a first insulating layer provided between the first electrode and the gate electrode; and a second insulating layer provided between the second electrode and the gate electrode. In a cross section parallel to a first direction from the first electrode to the second electrode, a first portion of the oxide semiconductor layer is provided between the gate insulating layer and the first electrode. In the cross section, a second portion of the oxide semiconductor layer is provided between the gate insulating layer and the second electrode.

A region containing a high proportion of crystal components and a region containing a high proportion of amorphous components are formed separately in one oxide semiconductor film. The region containing a high proportion of crystal components is formed so as to serve as a channel formation region and the other region is formed so as to contain a high proportion of amorphous components. It is preferable that an oxide semiconductor film in which a region containing a high proportion of crystal components and a region containing a high proportion of amorphous components are mixed in a self-aligned manner be formed. To separately form the regions which differ in crystallinity in the oxide semiconductor film, first, an oxide semiconductor film containing a high proportion of crystal components is formed and then process for performing amorphization on part of the oxide semiconductor film is conducted.

A region containing a high proportion of crystal components and a region containing a high proportion of amorphous components are formed separately in one oxide semiconductor film. The region containing a high proportion of crystal components is formed so as to serve as a channel formation region and the other region is formed so as to contain a high proportion of amorphous components. It is preferable that an oxide semiconductor film in which a region containing a high proportion of crystal components and a region containing a high proportion of amorphous components are mixed in a self-aligned manner be formed. To separately form the regions which differ in crystallinity in the oxide semiconductor film, first, an oxide semiconductor film containing a high proportion of crystal components is formed and then process for performing amorphization on part of the oxide semiconductor film is conducted.

An object of the present invention is to provide a semiconductor device having a novel structure in which in a data storing time, stored data can be stored even when power is not supplied, and there is no limitation on the number of writing. A semiconductor device includes a first transistor including a first source electrode and a first drain electrode; a first channel formation region for which an oxide semiconductor material is used and to which the first source electrode and the first drain electrode are electrically connected; a first gate insulating layer over the first channel formation region; and a first gate electrode over the first gate insulating layer. One of the first source electrode and the first drain electrode of the first transistor and one electrode of a capacitor are electrically connected to each other.

Provided is a semiconductor device that occupies a small area, a highly integrated semiconductor device, or a semiconductor device with high productivity. To fabricate an integrated circuit, a first insulating film is formed over a p-channel transistor; a transistor including an oxide semiconductor is formed over the first insulating film; a second insulating film is formed over the transistor; an opening, that is, a contact hole part of a sidewall of which is formed of the oxide semiconductor of the transistor, is formed in the first insulating film and the second insulating film; and an electrode connecting the p-channel transistor and the transistor including an oxide semiconductor to each other is formed.