| 摘要 |
PURPOSE:To reduce a variation in a threshold value voltage due to thickness of a gate insulating film by differentiating implanted ion peak density positions in n-channel type and p-channel type transistors. CONSTITUTION:After a p-type well 252, a field oxide film 260 and gate oxide films 264, 266 are grown on an Si substrate 250, B<+> ions, for example, are implanted. At this time, B<+> ions are implanted with an energy that B<+> ion flying stroke RP becomes equal as the thickness of the film 264 in an n-channel type transistor Q2, and B<+> ions are implanted so that ion flying path RP'' becomes sufficiently larger than the thickness of the film 266 in a p-channel type transistor Q1. As a result, the thickness of the film 264 is cancelled by the influence due to the variation in the ion implanting amount so that the threshold voltage of a gate electrode 274a becomes substantially constant in the transistor Q2. Since the influence due to a variation in the thickness of the film 266 is less in the transistor Q1, a gate threshold voltage becomes substantially constant. |
