A semiconductor device with favorable electrical characteristics is provided. A semiconductor device with stable electrical characteristics is provided. A highly reliable semiconductor device is provided. A semiconductor layer is formed, a gate insulating layer is formed over the semiconductor layer, a metal oxide layer is formed over the gate insulating layer, and a gate electrode which overlaps with part of the semiconductor layer is formed over the metal oxide layer. Then, a first element is supplied through the metal oxide layer and the gate insulating layer to a region of the semiconductor layer that does not overlap with the gate electrode. Examples of the first element include phosphorus, boron, magnesium, aluminum, and silicon. The metal oxide layer may be processed after the first element is supplied to the semiconductor layer.

A semiconductor substrate includes a base portion, an auxiliary layer and a surface layer. The auxiliary layer is formed on the base portion. The surface layer is formed on the auxiliary layer. The surface layer is in contact with a first main surface of the semiconductor substrate. The auxiliary layer has a different electrochemical dissolution efficiency than the base portion and the surface layer. At least a portion of the auxiliary layer and at least a portion of the surface layer are converted into a porous structure. Subsequently, an epitaxial layer is formed on the first main surface.

In a semiconductor device in which a channel formation region is included in an oxide semiconductor layer, an oxide insulating film below and in contact with the oxide semiconductor layer and a gate insulating film over and in contact with the oxide semiconductor layer are used to supply oxygen of the gate insulating film, which is introduced by an ion implantation method, to the oxide semiconductor layer.

A semiconductor substrate includes a base portion, an auxiliary layer and a surface layer. The auxiliary layer is formed on the base portion. The surface layer is formed on the auxiliary layer. The surface layer is in contact with a first main surface of the semiconductor substrate. The auxiliary layer has a different electrochemical dissolution efficiency than the base portion and the surface layer. At least a portion of the auxiliary layer and at least a portion of the surface layer are converted into a porous structure. Subsequently, an epitaxial layer is formed on the first main surface.

A solar cell includes: a semiconductor substrate which includes a first principal surface and a second principal surface; a first semiconductor layer of the first conductivity type disposed above the first principal surface; and a second semiconductor layer of a second conductivity type disposed below the second principal surface. The semiconductor substrate includes: a first impurity region of the first conductivity type; a second impurity region of the first conductivity type disposed between the first impurity region and the first semiconductor layer; and a third impurity region of the first conductivity type disposed between the first impurity region and the second semiconductor layer. A concentration of an impurity in the second impurity region is higher than a concentration of the impurity in the third impurity region, and the concentration of the impurity in the third impurity region is higher than a concentration of the impurity in the first impurity region.

A device includes a semiconductor substrate, a low-k dielectric layer over the semiconductor substrate, an isolation layer over the low-k dielectric layer, and a work function layer over the etch stop layer. The work function layer is an n-type work function layer. The device further includes a low-dimensional semiconductor layer on a top surface and a sidewall of the work function layer, source/drain contacts contacting opposing end portions of the low-dimensional semiconductor layer, and a dielectric doping layer over and contacting a channel portion of the low-dimensional semiconductor layer. The dielectric doping layer includes a metal selected from aluminum and hafnium, and the channel portion of the low-dimensional semiconductor layer further comprises the metal.

A device includes a semiconductor substrate, a low-k dielectric layer over the semiconductor substrate, an isolation layer over the low-k dielectric layer, and a work function layer over the isolation layer. The work function layer is an n-type work function layer. The device further includes a low-dimensional semiconductor layer on a top surface and a sidewall of the work function layer, source/drain contacts contacting opposing end portions of the low-dimensional semiconductor layer, and a dielectric doping layer over and contacting a channel portion of the low-dimensional semiconductor layer. The dielectric doping layer includes a metal selected from aluminum and hafnium, and the channel portion of the low-dimensional semiconductor layer further comprises the metal.

To provide a semiconductor device with favorable electrical characteristics. To provide a method for manufacturing a semiconductor device with high productivity. To reduce the temperatures in a manufacturing process of a semiconductor device. An island-like oxide semiconductor layer is formed over a first insulating film; a second insulating film and a first conductive film are formed in this order, covering the oxide semiconductor layer; oxygen is supplied to the second insulating film through the first conductive film; a metal oxide film is formed over the second insulating film in an atmosphere containing oxygen; a first gate electrode is formed by processing the metal oxide film; a third insulating film is formed, covering the first gate electrode and the second insulating film; and first heat treatment is performed. The second insulating film and the third insulating film each include oxide. The highest temperature in the above steps is 340° C. or lower.

A semiconductor device and a method for forming the semiconductor device are provided. The method includes providing a layer to-be-etched including first regions and second regions. A second region includes a second trench region. The method also includes forming a first mask layer over the first and second regions, and forming first trenches discretely in the first mask layer in the first regions. Moreover, the method includes forming a divided doped layer, and implanting dopant ions into the first mask layer disposed outside the second trench region. In addition, the method includes forming a mask sidewall spacer on a sidewall of a first trench after forming the divided doped layer and implanting the dopant ions into the first mask layer disposed outside the second trench region. Further, the method includes forming a second trench in the first mask layer in the second region.

A semiconductor device with favorable electrical characteristics is provided. A semiconductor device with stable electrical characteristics is provided. A highly reliable semiconductor device is provided. A semiconductor layer is formed, a gate insulating layer is formed over the semiconductor layer, a metal oxide layer is formed over the gate insulating layer, and a gate electrode which overlaps with part of the semiconductor layer is formed over the metal oxide layer. Then, a first element is supplied through the metal oxide layer and the gate insulating layer to a region of the semiconductor layer that does not overlap with the gate electrode. Examples of the first element include phosphorus, boron, magnesium, aluminum, and silicon. The metal oxide layer may be processed after the first element is supplied to the semiconductor layer.