Abstract: An object is to establish a processing technique in manufacture of a semiconductor device in which an oxide semiconductor is used. A gate electrode is formed over a substrate, a gate insulating layer is formed over the gate electrode, an oxide semiconductor layer is formed over the gate insulating layer, the oxide semiconductor layer is processed by wet etching to form an island-shaped oxide semiconductor layer, a conductive layer is formed to cover the island-shaped oxide semiconductor layer, the conductive layer is processed by dry etching to form a source electrode, and a drain electrode and part of the island-shaped oxide semiconductor layer is removed by dry etching to form a recessed portion in the island-shaped oxide semiconductor layer.

Abstract: A miniaturized transistor, a transistor with low parasitic capacitance, a transistor with high frequency characteristics, or a semiconductor device including the transistor is provided. The semiconductor device includes a first insulator, an oxide semiconductor over the first insulator, a first conductor and a second conductor that are in contact with the oxide semiconductor, a second insulator that is over the first and second conductors and has an opening reaching the oxide semiconductor, a third insulator over the oxide semiconductor and the second insulator, and a fourth conductor over the third insulator. The first conductor includes a first region and a second region. The second conductor includes a third region and a fourth region. The second region faces the third region with the first conductor and the first insulator interposed therebetween. The second region is thinner than the first region. The third region is thinner than the fourth region.

Abstract: A minute transistor is provided. A transistor with small parasitic capacitance is provided. A transistor with high frequency characteristics is provided. A semiconductor device including the transistor is provided. A semiconductor device includes an oxide semiconductor, a first conductor and a second insulator embedded in a first insulator, a second conductor and a third conductor. Edges of the second conductor and the third conductor facing each other each has a taper angle of 30 degree or more and 90 degree or less.

Abstract: A transistor including a semiconductor, a first conductor, a second conductor, a third conductor, a first insulator, and a second insulator is manufactured by forming a hard mask layer including a fourth conductor over the second insulator, a third insulator over the fourth conductor, forming an opening portion in the second insulator with the hard mask layer as the mask, eliminating the hard mask layer by forming the opening portion, and forming the first insulator and the first conductor in the opening portion.

Abstract: A miniaturized transistor having excellent electrical characteristics is provided with high yield. Further, a semiconductor device including the transistor and having high performance and high reliability is manufactured with high productivity. In a semiconductor device including a transistor in which an oxide semiconductor film including a channel formation region and low-resistance regions between which the channel formation region is sandwiched, a gate insulating film, and a gate electrode layer whose top surface and side surface are covered with an insulating film including an aluminum oxide film are stacked, a source electrode layer and a drain electrode layer are in contact with part of the oxide semiconductor film and the top surface and a side surface of the insulating film including an aluminum oxide film.

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: The on-state characteristics of a transistor are improved and thus, a semiconductor device capable of high-speed response and high-speed operation is provided. A highly reliable semiconductor device showing stable electric characteristics is made. The semiconductor device includes a transistor including a first oxide layer; an oxide semiconductor layer over the first oxide layer; a source electrode layer and a drain electrode layer in contact with the oxide semiconductor layer; a second oxide layer over the oxide semiconductor layer; a gate insulating layer over the second oxide layer; and a gate electrode layer over the gate insulating layer. An end portion of the second oxide layer and an end portion of the gate insulating layer overlap with the source electrode layer and the drain electrode layer.

Abstract: A method for manufacturing an oxide semiconductor layer, comprising forming an oxide semiconductor layer over an insulating layer so as to be along with a curved surface of a projecting structural body of the insulating layer, wherein a length of the projecting structural body in a height direction is larger than a width of the projecting structural body, is provided.

Abstract: A semiconductor device in which parasitic capacitance is reduced is provided. A first oxide insulating layer and a first oxide semiconductor layer are sequentially formed over a first insulating layer. A first conductive layer is formed over the first oxide semiconductor layer and etched to form a second conductive layer. The first oxide insulating layer and the first oxide semiconductor layer are etched with the second conductive layer as a mask to form a second oxide insulating layer and a second oxide semiconductor layer. A planarized insulating layer is formed over the first insulating layer and the second conductive layer. A second insulating layer, a source electrode layer, and a drain electrode layer are formed by etching the planarized insulating layer and the second conductive layer. A third oxide insulating layer, a gate insulating layer, and a gate electrode layer are formed over the second oxide semiconductor layer.

Abstract: A semiconductor device includes a first oxide insulating layer over a first insulating layer, an oxide semiconductor layer over the first oxide insulating layer, a source electrode layer and a drain electrode layer over the oxide semiconductor layer, a second insulating layer over the source electrode layer and the drain electrode layer, a second oxide insulating layer over the oxide semiconductor layer, a gate insulating layer over the second oxide insulating layer, a gate electrode layer over the gate insulating layer, and a third insulating layer over the second insulating layer, the second oxide insulating layer, the gate insulating layer, and the gate electrode layer. A side surface portion of the second insulating layer is in contact with the second oxide insulating layer. The gate electrode layer includes a first region and a second region. The first region has a width larger than that of the second region.

Abstract: A semiconductor device that occupies a small area and has a high degree of integration is provided. The semiconductor device includes a first insulating layer, a conductive layer, and a second insulating layer. The conductive layer is between the first insulating layer and the second insulating layer. The first insulating layer, the conductive layer, and the second insulating layer overlap with each other in a region. A contact plug penetrates the first insulating layer, the conductive layer, and the second insulating layer. In a depth direction from the second insulating layer to the first insulating layer, a diameter of the contact plug changes to a smaller value at an interface between the second insulating layer and the conductive layer.

Abstract: A substrate having an insulating surface is prepared; a stacked film including a first oxide semiconductor layer and a second oxide semiconductor layer is formed over the substrate; a mask layer is formed over part of the stacked film and then dry etching treatment is performed, so that the stacked film is removed, with a region provided with the mask layer remaining, and a reaction product is formed on a side surface of the remaining stacked film; the reaction product is removed by wet etching treatment after removal of the mask layer; a source electrode and a drain electrode are formed over the stacked film; and a third oxide semiconductor layer, a gate insulating film, and a gate electrode are stacked and formed in this order over the stacked film, and the source electrode and the drain electrode.

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 semiconductor device which includes an oxide semiconductor and has favorable electrical characteristics is provided. In the semiconductor device, an oxide semiconductor film and an insulating film are formed over a substrate. Side surfaces of the oxide semiconductor film are in contact with the insulating film. The oxide semiconductor film includes a channel formation region and regions containing a dopant between which the channel formation region is sandwiched. A gate insulating film is formed on and in contact with the oxide semiconductor film. A gate electrode with sidewall insulating films is formed over the gate insulating film. A source electrode and a drain electrode are formed in contact with the oxide semiconductor film and the insulating film.

Abstract: To provide a semiconductor device which occupies a small area and is highly integrated. The semiconductor device includes an oxide semiconductor layer, an electrode layer, and a contact plug. The electrode layer includes one end portion in contact with the oxide semiconductor layer and the other end portion facing the one end portion. The other end portion includes a semicircle notch portion when seen from the above. The contact plug is in contact with the semicircle notch portion.

Abstract: When an oxide semiconductor film is microfabricated, with the use of a hard mask, unevenness of a side surface of the oxide semiconductor film can be suppressed. Specifically, a semiconductor device comprises an oxide semiconductor film over an insulating surface; a first hard mask and a second hard mask over the oxide semiconductor film; a source electrode over the oxide semiconductor film and the first hard mask; a drain electrode over the oxide semiconductor film and the second hard mask; a gate insulating film over the source electrode and the drain electrode; and a gate electrode overlapping with the gate insulating film and the oxide semiconductor film, and the first and second hard masks have conductivity.

Abstract: A minute transistor is provided. Alternatively, a transistor with low parasitic capacitance is provided. Alternatively, a transistor having high frequency characteristics is provided. Alternatively, a novel transistor is provided. A transistor including a semiconductor, a first conductor, a second conductor, a third conductor, a first insulator, and a second insulator is manufactured by forming a hard mask layer including a fourth conductor over the second insulator, a third insulator over the fourth conductor, forming an opening portion in the second insulator with the hard mask layer as the mask, eliminating the hard mask layer by forming the opening portion, and forming the first insulator and the first conductor in the opening portion.

Abstract: First to third insulators are successively formed in this order over a first conductor over a semiconductor substrate; a hard mask with a first opening is formed thereover; a resist mask with a second opening is formed thereover; a third opening is formed in the third insulator; a fourth opening is formed in the second insulator; the resist mask is removed; a fifth opening is formed in the first to third insulators; a second conductor is formed to cover an inner wall and a bottom surface of the fifth opening; a third conductor is formed thereover; polishing treatment is performed so that the hard mask is removed, and that levels of top surfaces of the second and third conductors and the third insulator are substantially equal to each other; and an oxide semiconductor is formed thereover. The second insulator is less permeable to hydrogen than the first and third insulators, the second conductor is less permeable to hydrogen than the third conductor.

Abstract: A semiconductor device includes a first oxide insulating layer over a first insulating layer, an oxide semiconductor layer over the first oxide insulating layer, a source electrode layer and a drain electrode layer over the oxide semiconductor layer, a second insulating layer over the source electrode layer and the drain electrode layer, a second oxide insulating layer over the oxide semiconductor layer, a gate insulating layer over the second oxide insulating layer, a gate electrode layer over the gate insulating layer, and a third insulating layer over the second insulating layer, the second oxide insulating layer, the gate insulating layer, and the gate electrode layer. A side surface portion of the second insulating layer is in contact with the second oxide insulating layer. The gate electrode layer includes a first region and a second region. The first region has a width larger than that of the second region.

Abstract: An object is to establish a processing technique in manufacture of a semiconductor device in which an oxide semiconductor is used. A gate electrode is formed over a substrate, a gate insulating layer is formed over the gate electrode, an oxide semiconductor layer is formed over the gate insulating layer, the oxide semiconductor layer is processed by wet etching to form an island-shaped oxide semiconductor layer, a conductive layer is formed to cover the island-shaped oxide semiconductor layer, the conductive layer is processed by dry etching to form a source electrode, and a drain electrode and part of the island-shaped oxide semiconductor layer is removed by dry etching to form a recessed portion in the island-shaped oxide semiconductor layer.