| 摘要 |
PURPOSE:To form deeply a high density impurity layer in a semiconductor substrate without forming in the bases of source and drain regions by a method wherein an opening to form a gate electrode is prepared on a polycrystalline Si layer using a mask, and an impurity is introduced only to the portion of substrate under the gate. CONSTITUTION:A silicon dioxide film 32 is formed on the surface of a p-type silicon semiconductor substrate 10, a polycrystalline layer 34 is formed on it by vapor growth and a silicon dioxide film 36 and a silicon nitride film 38 are formed on it. An opening is made at the portion of the silicon nitride film 38 to form a gate electrode using photo resists 40. Then a p-type impurity boron B is introduced to a channel region forming part by ion implantation. A silicon dioxide film 36a is formed thickly only at the opening part by thermal oxidation, and etching is performed reaching to the film 36 to remain the thick oxide film 36a as a mask. Finally a gate electrode 16 is formed by etching. |
