Semiconductor device with improved element isolation and operation rate

摘要

A lower electrode of a capacitor for use in a semiconductor device includes a first semiconductor layer having a predetermined impurity concentration and a second semiconductor layer having an impurity concentration higher than that of the first semiconductor layer. As a result, intensification of an electric field at an end portion of the capacitor can be reduced. In addition, a word line is formed of a buffer layer and a main conductor layer to reduce a parasitic capacitance between the lower electrode of the capacitor and the word line.