Abstract: A semiconductor device with favorable reliability is provided. The semiconductor device includes a first oxide, a second oxide over the first oxide, a first insulator over the second oxide, a first conductor over the first insulator, and a second conductor and a third conductor over the second oxide. The second conductor includes a first region and a second region, the third conductor includes a third region and a fourth region, the second region is positioned above the first region, the fourth region is positioned above the third region, and each of the second conductor and the third conductor contains tantalum and nitrogen. The atomic ratio of nitrogen to tantalum in the first region is higher than the atomic ratio of nitrogen to tantalum in the second region, and the atomic ratio of nitrogen to tantalum in the third region is higher than the atomic ratio of nitrogen to tantalum in the fourth region.

Abstract: A semiconductor device having favorable electrical characteristics is provided. The semiconductor device includes a conductor, a first insulator in contact with a side surface of the conductor, a second insulator in contact with a top surface of the conductor and a top surface of the first insulator, and an oxide over the second insulator. The oxide includes a region that overlaps with the conductor with the second insulator interposed therebetween. The maximum height of a roughness curve (Rz) of the top surface of the conductor is 6.0 nm or smaller. The region includes crystals, and c-axes of the crystals are aligned in the normal direction of the top surface of the conductor.

Abstract: A semiconductor device having favorable electrical characteristics is provided. The semiconductor device includes a conductor, a first insulator in contact with a side surface of the conductor, a second insulator in contact with a top surface of the conductor and a top surface of the first insulator, and an oxide over the second insulator. The oxide includes a region that overlaps with the conductor with the second insulator interposed therebetween. The maximum height of a roughness curve (Rz) of the top surface of the conductor is 6.0 nm or smaller. The region includes crystals, and c-axes of the crystals are aligned in the normal direction of the top surface of the conductor.

Abstract: A semiconductor device with favorable reliability is provided. The semiconductor device includes a first insulator; a second insulator positioned over the first insulator; an oxide positioned over the second insulator; a first conductor and a second conductor positioned apart from each other over the oxide; a third insulator positioned over the oxide, the first conductor, and the second conductor; a third conductor positioned over the third insulator and at least partly overlapping with a region between the first conductor and the second conductor; a fourth insulator positioned to cover the oxide, the first conductor, the second conductor, the third insulator, and the third conductor; a fifth insulator positioned over the fourth insulator; and a sixth insulator positioned over the fifth insulator.

Abstract: A semiconductor device that can be miniaturized or highly integrated is provided. The semiconductor device includes a capacitor, an electrode, and an interlayer film. The transistor includes a semiconductor layer, a gate, a source, and a drain; the transistor and the capacitor are placed to be embedded in the interlayer film. Below the semiconductor layer, one of the source and the drain is in contact with the electrode. Above the semiconductor layer, the other of the source and the drain is in contact with one electrode of the capacitor.

Abstract: A semiconductor device having favorable electrical characteristics is provided. The semiconductor device includes a conductor, a first insulator in contact with a side surface of the conductor, a second insulator in contact with a top surface of the conductor and a top surface of the first insulator, and an oxide over the second insulator. The oxide includes a region that overlaps with the conductor with the second insulator interposed therebetween. The maximum height of a roughness curve (Rz) of the top surface of the conductor is 6.0 nm or smaller. The region includes crystals, and c-axes of the crystals are aligned in the normal direction of the top surface of the conductor.

Abstract: An imaging device suitable for detecting infrared light is provided. The imaging device includes a first layer, a second layer, a third layer, and a fourth layer, which are stacked in this order. The first layer includes an infrared-light-transmitting filter. The second layer includes single crystal silicon. The third layer includes a device-formation layer. The fourth layer includes a support substrate. The second layer includes a photoelectric-conversion device whose light-absorption layer is the single crystal silicon. The third layer includes a transistor which includes a metal oxide in its channel formation region. The photoelectric-conversion device and the transistor are electrically connected. The photoelectric-conversion device receives light which has passed through the infrared-light-transmitting filter.

Abstract: A semiconductor device having favorable electrical characteristics is provided. The semiconductor device includes a conductor, a first insulator in contact with a side surface of the conductor, a second insulator in contact with a top surface of the conductor and a top surface of the first insulator, and an oxide over the second insulator. The oxide includes a region that overlaps with the conductor with the second insulator interposed therebetween. The maximum height of a roughness curve (Rz) of the top surface of the conductor is 6.0 nm or smaller. The region includes crystals, and c-axes of the crystals are aligned in the normal direction of the top surface of the conductor.

Abstract: A semiconductor device with favorable reliability is provided. The semiconductor device includes a first insulator; a second insulator positioned over the first insulator; an oxide positioned over the second insulator; a first conductor and a second conductor positioned apart from each other over the oxide; a third insulator positioned over the oxide, the first conductor, and the second conductor; a third conductor positioned over the third insulator and at least partly overlapping with a region between the first conductor and the second conductor; a fourth insulator positioned to cover the oxide, the first conductor, the second conductor, the third insulator, and the third conductor; a fifth insulator positioned over the fourth insulator; and a sixth insulator positioned over the fifth insulator.

Abstract: A semiconductor device with a high on-state current is provided. The semiconductor device includes a first insulator, a first oxide over the first insulator, a second oxide over the first oxide, a first conductor and a second conductor over the second oxide, a third oxide over the second oxide, a second insulator over the third oxide, a third conductor that is located over the second insulator and overlaps with the third oxide, a third insulator that is located over the first insulator and in contact with a side surface of the first oxide, a side surface of the second oxide, a side surface of the first conductor, a top surface of the first conductor, a side surface of the second conductor, and a top surface of the second conductor, and a fourth insulator over the third conductor, the second insulator, the third oxide, and the third insulator. The fourth insulator is in contact with a top surface of each of the third conductor, the second insulator, and the third oxide.

Abstract: A semiconductor device with favorable reliability is provided. The semiconductor device includes a first oxide, a second oxide over the first oxide, a first insulator over the second oxide, a first conductor over the first insulator, and a second conductor and a third conductor over the second oxide. The second conductor includes a first region and a second region, the third conductor includes a third region and a fourth region, the second region is positioned above the first region, the fourth region is positioned above the third region, and each of the second conductor and the third conductor contains tantalum and nitrogen. The atomic ratio of nitrogen to tantalum in the first region is higher than the atomic ratio of nitrogen to tantalum in the second region, and the atomic ratio of nitrogen to tantalum in the third region is higher than the atomic ratio of nitrogen to tantalum in the fourth region.

Abstract: A semiconductor device with favorable reliability is provided. The semiconductor device includes a first insulator; a second insulator positioned over the first insulator; an oxide positioned over the second insulator; a first conductor and a second conductor positioned apart from each other over the oxide; a third insulator positioned over the oxide, the first conductor, and the second conductor; a third conductor positioned over the third insulator and at least partly overlapping with a region between the first conductor and the second conductor; a fourth insulator positioned to cover the oxide, the first conductor, the second conductor, the third insulator, and the third conductor; a fifth insulator positioned over the fourth insulator; and a sixth insulator positioned over the fifth insulator.

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 that can be miniaturized or highly integrated is provided. The semiconductor device includes a capacitor, an electrode, and an interlayer film. The transistor includes a semiconductor layer, a gate, a source, and a drain; the transistor and the capacitor are placed to be embedded in the interlayer film. Below the semiconductor layer, one of the source and the drain is in contact with the electrode. Above the semiconductor layer, the other of the source and the drain is in contact with one electrode of the capacitor.

Abstract: A semiconductor device that can be miniaturized or highly integrated is provided. The semiconductor device includes an oxide; a first conductor and a second conductor provided apart from each other over the oxide; a third conductor including a region that is over the oxide and overlaps with a region between the first conductor and the second conductor; a first insulator over the third conductor; a fourth conductor that is electrically connected to the first conductor through a first opening provided in the first insulator; a second insulator that is provided over the first insulator and that is provided over the fourth conductor in the first opening; a fifth conductor overlapping with the fourth conductor with the second insulator positioned therebetween in the first opening; and a sixth conductor electrically connected to the second conductor in a second opening provided in the first insulator and the second insulator.

Abstract: A semiconductor device having favorable electrical characteristics is provided. The semiconductor device includes a conductor, a first insulator in contact with a side surface of the conductor, a second insulator in contact with a top surface of the conductor and a top surface of the first insulator, and an oxide over the second insulator. The oxide includes a region that overlaps with the conductor with the second insulator interposed therebetween. The maximum height of a roughness curve (Rz) of the top surface of the conductor is 6.0 nm or smaller. The region includes crystals, and c-axes of the crystals are aligned in the normal direction of the top surface of the conductor.

Abstract: A semiconductor device with favorable reliability is provided. The semiconductor device includes a first insulator; a second insulator positioned over the first insulator; an oxide positioned over the second insulator; a first conductor and a second conductor positioned apart from each other over the oxide; a third insulator positioned over the oxide, the first conductor, and the second conductor; a third conductor positioned over the third insulator and at least partly overlapping with a region between the first conductor and the second conductor; a fourth insulator positioned to cover the oxide, the first conductor, the second conductor, the third insulator, and the third conductor; a fifth insulator positioned over the fourth insulator; and a sixth insulator positioned over the fifth insulator.

Abstract: A semiconductor device with a high on-state current is provided. The semiconductor device includes a first insulator, a first oxide over the first insulator, a second oxide over the first oxide, a first conductor and a second conductor over the second oxide, a third oxide over the second oxide, a second insulator over the third oxide, a third conductor that is located over the second insulator and overlaps with the third oxide, a third insulator that is located over the first insulator and in contact with a side surface of the first oxide, a side surface of the second oxide, a side surface of the first conductor, a top surface of the first conductor, a side surface of the second conductor, and a top surface of the second conductor, and a fourth insulator over the third conductor, the second insulator, the third oxide, and the third insulator. The fourth insulator is in contact with a top surface of each of the third conductor, the second insulator, and the third oxide.

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 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.