| 摘要 |
PURPOSE:To reduce an occupation area of a resistance element by employing a high impurity concentration buried layer as the resistance element and forming most part of the high impurity concentration buried layer within a projection region of a MOSFET. CONSTITUTION:A P type semiconductor region 5-1 is formed in an N type semiconductor region 4 by impurity diffusion, constituting a well region of a longitudinal power MOSFET 50. An N<+> type semiconductor region 7 constitut ing a source region. An N<+> type semiconductor region 6 formed on the surface fraction of an N<+> type semiconductor region 3 forms a drain contact region of a longitudinal power MOSFET 50. P<+> type semiconductor regions 9-1, 9-2 formed in the N type semiconductor region 4 constitute a drain region and a source region of a P MOS transistor 18 of a CMOS circuit, respectively. Drain resistance formed in a projection region of the longitudinal power MOSFET 50 is produced owing to the N<+> semiconductor region 3 and the N type semiconductor region 4, whereby an occupation area of electrostatic break down protective element in the semiconductor device can be reduced. |
