| 摘要 |
PURPOSE:To reduce the depth of a trench for forming element separately without deteriorating element separating characteristics such as element separating pressure resistance by selectively forming a channel stopper layer only on the center of the trench bottom part. CONSTITUTION:Since polysilicon 7b, which is much thicker than the projected range of boron which is ion implanted on a trench side wall, is left before the boron ion implantation for forming a channel stopper layer 6 at the trench bottom, the boron ion implanted on the polysilicon 7b on the trench side wall stays in the polysilicon 7b, and the boron ion is not implanted on the P type silicon substrate 1 on the trench side wall, an N type diffused layer 2 and an epitaxial layer 3. Thus, the extension of the channel stopper layer 6 to the trench side wall is suppressed, the P type channel stopper layer 6, which is denser than the P type silicon substrate 1, is prevented from being brought into contact with an N type diffused layer 2 in the vicinity of the trench and the epitaxial layer 3, and excellent element separating characteristic is formed with good reproducibility. |
