What is proposed is a method of producing at least two differently heavily doped subzones (3, 5) predominantly doped with a first dopant type in a silicon substrate (1), in particular for a solar cell. The method comprises: covering at least a first subzone (3) of the silicon substrate (1) in which a heavier doping with the first dopant type is to be produced with a doping layer (7) of borosilicate glass, wherein at least a second subzone (5) of the silicon substrate (1) in which a lighter doping with the first dopant type is to be produced is not covered with the doping layer (7), and wherein boron as a dopant of a second dopant type differing from the first dopant type and oppositely polarized with respect to the same is included in the layer (7), and; heating the such prepared silicon substrate (1) to temperatures above 300 C., preferably above 900 C., in a furnace in an atmosphere containing significant quantities of the first dopant type. Additionally, at least a third doped subzone (15) doped with the second dopant type may be produced by the method additionally comprising, prior to the heating, a covering of the doping layer (7), above the third doped subzone (15) to be produced, with a further layer (17) acting as a diffusion barrier for the first dopant type. The method uses the observation that a borosilicate glass layer seems to promote an in-diffusion of phosphorus from a gas atmosphere and may substantially facilitate a manufacturing for example of solar cells, in particular back contact solar cells.

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 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 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 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.

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 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 thin film transistor includes a gate electrode. The thin film transistor further includes an oxide semiconductor layer which includes at least indium and is usable as a channel layer, wherein a region of the oxide semiconductor layer closest to the gate electrode includes fluorine. The thin film transistor further includes a gate insulating layer between the gate electrode and the oxide semiconductor layer. The thin film transistor further includes a fluorine-including layer which includes fluorine and is between the gate electrode and the gate insulating layer.

A semiconductor device according to an embodiment includes: an oxide insulating layer; an oxide semiconductor layer; a gate electrode; a gate insulating layer; and a first insulating layer, wherein the semiconductor device is divided into a first to a third regions, a thickness of the gate insulating layer in the first region is 200 nm or more, the gate electrode contacts the first insulating layer in the first region, the oxide semiconductor layer contacts the first insulating layer in the second region, an amount of impurities contained in the oxide semiconductor layer in the second region is greater than an amount of impurities contained in the oxide semiconductor layer in the first region, and an amount of impurities contained in the oxide insulating layer in the third region is greater than an amount of impurities contained in the oxide insulating layer in the second region.

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.