| 摘要 |
PURPOSE:To increase the breakdown strength of a thyristor, etc. by keeping the width of trenches constant and forming the regular-level mesa trenches. CONSTITUTION:When trenches reaching an N<->E region 5 as a low concentration region from a P<+>E region 6 as a high concentration region are worked to a semiconductor wafer l by a diamond drill 20, ring-shaped regular-level mesa trenches 25, width of which is widened with deepening from a main surface, are shaped. A surface electric field is lowered by the trenches 25, and surface breakdown is difficult to be generated, thus increasing the breakdown strength of a thyristor, etc. |
