Semiconductor device and method for fabricating the same

摘要

A core section complementary transistor and a memory cell section complementary transistor are formed on a semiconductor substrate of a first conductivity type. The core section complementary transistor has a first well of a second conductivity type provided in the semiconductor substrate, a first core section MOS transistor provided on the first well of the second conductivity type, a second core section MOS transistor provided on the semiconductor substrate a device separation film which separates the first core section MOS transistor and the second core section MOS transistor from each other, and a well of the first conductivity type provided under a part of the device separation film which is closer to the second core section MOS transistor. The first core section MOS transistor has source-drain regions of the first conductivity type. The second core section MOS transistor has source-drain regions of the second conductivity type. The well of the first conductivity type has an impurity concentration higher than that of the semiconductor substrate.