An object is to manufacture a highly reliable semiconductor device including a thin film transistor with stable electric characteristics. In a method for manufacturing a semiconductor device including a thin film transistor in which an oxide semiconductor film is used for a semiconductor layer including a channel formation region, heat treatment (for dehydration or dehydrogenation) is performed to improve the purity of the oxide semiconductor film and reduce impurities including moisture or the like. After that, slow cooling is performed under an oxygen atmosphere. Besides impurities including moisture or the like exiting in the oxide semiconductor film, heat treatment causes reduction of impurities including moisture or the like exiting in a gate insulating layer and those in interfaces between the oxide semiconductor film and films which are provided over and below the oxide semiconductor and in contact therewith.

An object is to manufacture a highly reliable semiconductor device including a thin film transistor with stable electric characteristics. In a method for manufacturing a semiconductor device including a thin film transistor in which an oxide semiconductor film is used for a semiconductor layer including a channel formation region, heat treatment (for dehydration or dehydrogenation) is performed to improve the purity of the oxide semiconductor film and reduce impurities including moisture or the like. After that, slow cooling is performed under an oxygen atmosphere. Besides impurities including moisture or the like exiting in the oxide semiconductor film, heat treatment causes reduction of impurities including moisture or the like exiting in a gate insulating layer and those in interfaces between the oxide semiconductor film and films which are provided over and below the oxide semiconductor and in contact therewith.

A thin film transistor includes: a substrate; an undercoat layer disposed on the substrate; an oxide semiconductor layer formed above the undercoat layer and including at least indium; a gate insulating layer located opposite the undercoat layer with the oxide semiconductor layer being between the gate insulating layer and the undercoat layer; a gate electrode located opposite the oxide semiconductor layer with the gate insulating layer being between the gate electrode and the oxide semiconductor layer; and a source electrode and a drain electrode electrically connected to the oxide semiconductor layer, wherein fluorine is included in a region which is an internal region in the oxide semiconductor layer and is close to the undercoat layer.

A thin film transistor includes: a substrate; an undercoat layer disposed on the substrate; an oxide semiconductor layer formed above the undercoat layer and including at least indium; a gate insulating layer located opposite the undercoat layer with the oxide semiconductor layer being between the gate insulating layer and the undercoat layer; a gate electrode located opposite the oxide semiconductor layer with the gate insulating layer being between the gate electrode and the oxide semiconductor layer; and a source electrode and a drain electrode electrically connected to the oxide semiconductor layer, wherein fluorine is included in a region which is an internal region in the oxide semiconductor layer and is close to the undercoat layer.

In a manufacturing process of a transistor including an oxide semiconductor film, oxygen doping treatment is performed on the oxide semiconductor film, and then heat treatment is performed on the oxide semiconductor film and an aluminum oxide film provided over the oxide semiconductor film. Consequently, an oxide semiconductor film which includes a region containing more oxygen than a stoichiometric composition is formed. The transistor formed using the oxide semiconductor film can have high reliability because the amount of change in the threshold voltage of the transistor by a bias-temperature stress test (BT test) is reduced.

In a manufacturing process of a transistor including an oxide semiconductor film, oxygen doping treatment is performed on the oxide semiconductor film, and then heat treatment is performed on the oxide semiconductor film and an aluminum oxide film provided over the oxide semiconductor film. Consequently, an oxide semiconductor film which includes a region containing more oxygen than a stoichiometric composition is formed. The transistor formed using the oxide semiconductor film can have high reliability because the amount of change in the threshold voltage of the transistor by a bias-temperature stress test (BT test) is reduced.

A semiconductor device and a manufacturing method thereof are provided. The semiconductor device includes a gate layer, a low-doping semiconductor layer, a crystalline ferroelectric layer and source and drain terminals. The crystalline ferroelectric layer is disposed between the gate layer and the low-doping semiconductor layer. The source terminal and the drain terminal are disposed on the low-doping semiconductor layer.

A semiconductor device and a manufacturing method thereof are provided. The semiconductor device includes a gate layer, a low-doping semiconductor layer, a crystalline ferroelectric layer and source and drain terminals. The crystalline ferroelectric layer is disposed between the gate layer and the low-doping semiconductor layer. The source terminal and the drain terminal are disposed on the low-doping semiconductor layer.

A method includes placing a semiconductor substrate in a deposition chamber, wherein the semiconductor substrate includes a trench, and performing an atomic layer deposition (ALD) process to deposit a dielectric material within the trench, including flowing a first precursor of the dielectric material into the deposition chamber as a gas phase; flowing a second precursor of the dielectric material into the deposition chamber as a gas phase; and controlling the pressure and temperature within the deposition chamber such that the second precursor condenses on surfaces within the trench as a liquid phase of the second precursor, wherein the liquid phase of the second precursor has capillarity.

A semiconductor device includes: a first semiconductor layer having an N conductive type and made of a gallium oxide-based semiconductor; and a second semiconductor layer made of a gallium oxide-based semiconductor, in contact with the first semiconductor layer, and having the N conductive type with an electrically active donor concentration higher than an electrically active donor concentration of the first semiconductor layer. A difference between a donor concentration of the first semiconductor layer and a donor concentration of the second semiconductor layer is smaller than a difference between the electrically active donor concentration of the first semiconductor layer and the electrically active donor concentration of the second semiconductor layer.