Semiconductor device including arrangement for reducing junction

Abstract

An arrangement is provided to decrease the junction degradation caused by the leakage current at a p-n junction in semiconductor devices. This arrangement can be useful for a variety of devices, and is especially effective for reducing junction degradation at the source or drain region of a MOSFET. To achieve such a reduction, a p-n junction layer is provided at a p-n junction of a semiconductor region and a substrate. Carrier concentration distributions of a p-type layer and an n-type layer of the p-n junction layer are set so that an electric field which tends to be increased by a local electric field enhancement in a depletion layer of the p-n junction due to a precipitate introduced from a semiconductor surface will not exceed 1 MV/cm. When the depth of a depletion layer of the p-type layer or the n-type layer is referred to as Xp or Xn, and the slope of the carrier concentration, Ap or An, the following relation is provided: