A semiconductor device which has satisfactory characteristics is provided. The semiconductor device includes a TFT manufactured by using a satisfactory crystalline semiconductor film and a circuit manufactured by using the TFT. An n-type impurity element (typically, phosphorous) is added to a gettering region of an n-channel TFT. A p-type impurity element (typically, boron) and a rare gas element (typically, argon) are added to a gettering region of a p-channel TFT. Then, there is performed heat treatment for gettering a catalytic element that remains in a semiconductor film.
A semiconductor device having a crystalline semiconductor film with production of a cavity suppressed and a manufacturing method thereof. A manufacturing method of a semiconductor device according to the invention comprises the steps of forming an amorphous silicon film on a substrate having an insulating surface, adding a metal element such as Ni for promoting crystallization to the amorphous silicon film, applying heat treatment to crystallize the amorphous silicon film, so that a crystalline silicon film is formed on the substrate, removing a silicon oxide film formed on the surface of the crystalline silicon film due to the heat treatment by a solution containing organic solvent and fluoride, and irradiating laser light or strong light to the crystalline silicon film.
An object of the present invention is to provide a method for manufacturing a semiconductor device in which, after crystallizing by using an element that promotes crystallization, holes are prevented from being generated in a crystalline semiconductor film with a concentration of the element in the crystalline semiconductor film decreased by performing gettering. To solve the problem, as a feature of the structure of the invention, in the case of removing a silicon oxide film formed over the semiconductor film, an etchant made of a solution containing fluorine and a substance having surface activity is used.
According to the present invention, an impurity region, to which a rare gas element (also called a rare gas) and one kind or a plurality of kinds of elements selected from the group consisting of H, H.sub.2, O, O.sub.2, and P are added, are formed in a semiconductor film having a crystalline structure, using a mask, and gettering for segregating a metal element contained in the semiconductor film to the impurity region by heat treatment. Thereafter, pattering is conducted using the mask, whereby a semiconductor layer made of the semiconductor film having a crystalline structure is formed.
