Semiconductor element and manufacturing method thereof

摘要

A p-channel MOSFET ( 1 ) includes a semiconductor substrate ( 2 ), an epitaxial region ( 3 ), a second diffusion region ( 6 ), and a drain region. The epitaxial region ( 3 ) is formed on the upper surface of the semiconductor substrate ( 2 ). The second diffusion region ( 6 ) is formed in a predetermined upper surface area of the epitaxial region ( 3 ). The second diffusion region ( 6 ) has a central portion ( 6 a) and a peripheral portion ( 6 b). The central portion ( 6 a) is formed substantially at the center of the epitaxial region ( 3 ) and formed thicker than the peripheral portion ( 6 b). The peripheral portion ( 6 b) is formed in an annular shape so as to surround the central portion ( 6 a). The drain region ( 7 ) is formed in an upper surface area of the central portion ( 6 a) of the second diffusion region ( 6 ).