| 摘要 |
PURPOSE:To reduce the thickness of an active region, to raise the mobility of a carrier, to lower a threshold voltage and to reduce the resistances of a source region and an active region by forming source and drain regions of a laminated film of a polycrystalline silicon film for forming the active region and a low resistance film. CONSTITUTION:A doped polysilicon film 13 which is reduced in the resistance value by the addition of an impurity is coated by a CVD method on the surface of a silicon dioxide film 12. A central portion interposed between the source and drain regions of the film 13 (the portions at both sides of the drawing) remain except the both regions is removed by photoetching. Then, a polysilicon film 14 is coated in the necessary thickness on the active layer by a CVD method. The thickness of the film 14 at this time is reduced to improve the characteristic. Then, the laminated films 14 and 13 are removed at both sides. Here, the portion interposed between the films 14 and 13 becomes an active region. |
