Abstract: Disclosed is a semiconductor device having a driver circuit operable at high speed and a method for manufacturing same. An active matrix liquid crystal display device uses a polysilicon film for its TFT active layer constituting a pixel matrix circuit because of low off current characteristics. On the other hand, a TFT active layer constituting driver circuits and a signal processing circuit uses a poly silicon germanium film because of high speed operation characteristics.

Abstract: A metal element density is lowered in a crystalline silicon film obtained by four hour treatment at about 550.degree. C. by using a catalyst metal which accelerates crystallization. At the same time, a crystalline silicon film can be obtained which has a high crystallinity. For this purpose, extremely oxide film 13 is formed on an amorphous silicon film formed on this glass substrate in the beginning. An aqueous solution of acetate added with 10 to 200 ppm (need adjustment) of catalyst element like nickel or the like is dripped. This state is held for a predetermined time. Then the spin drying is performed by using a spinner. The film is crystallized by four hour treatment at 550.degree. C. Then a localized nickel component is removed by the fluoric acid treatment. Further, the crystalline silicon film is obtained by laser light irradiation. Then a crystalline silicon film is obtained having a low density of metal element and a small defect density by four hour heat treatment at 550.degree. C.