| 摘要 |
PROBLEM TO BE SOLVED: To provide a semiconductor device having high breakdown strength in which voltage drop is reduced under on state by forming a second conductivity type buried layer having a gap serving as a current path and a potential different from any electrode of semiconductor device when a depletion layer extending from the vicinity of a main electrode is reached in a first conductivity type semiconductor layer. SOLUTION: An n-type base layer 15 and a p-type buried layer 16 are formed sequentially on a p-type buried layer 14. Each of the p-type buried layer 14, 16 is formed to satisfy a relationship 5t>W between the thickness (t) and the interval W thus widening the current path. When the applying voltage reaches 200V, an n-type base layer 17 is depleted as a depletion layer extends to the upper p-type buried layer 16 which thereby enters into punch through state and the potential is fixed. When the applying voltage exceeds 200V, a new depletion layer spreads from the p-type buried layer 16 toward the drain electrode 12 side into an intermediate n-type base layer 15 and a strongest point of field appears on the p-type buried layer 16 side. |
