| 摘要 |
PURPOSE:To increase the concentration of an impurity of a first conductivity type at the bottom section of a trench by implanting ions in the vertical direction after forming the trench into a semiconductor substrate of the first conductivity type. CONSTITUTION:After a trench is formed into a semiconductor substrate 2 of the first conductivity type in the vertical direction from the surface toward its inside and ions are implanted into the bottom section and vicinity of the trench in the vertical and oblique directions so as to form an impurity area 1 of the first conductivity type in the bottom and side walls of the trench. Then ions are implanted into the bottom and vicinity of the trench in an oblique direction so as to form an impurity area 3 of the second conductivity type in the impurity area 1 of the first conductivity type. Therefore, a p-type impurity area 1 having a concentration higher than that of the substrate 2 can be surely formed to a prescribed depth between the n-type impurity area 3 and substrate 2 in the trench. |
