Semiconductor structures and manufacturing methods thereof

Abstract

Various methods for manufacturing semiconductor structures are provided. An embodiment method includes forming a first patterned hard mask and epitaxial layer on a semiconductor substrate, and forming a first doped region in the epitaxial layer by performing a first implantation through the first patterned hard mask. A second doped region is formed in the epitaxial layer by performing a second implantation through the first patterned hard mask, with the first doped region at least partially overlapping the second doped region. A second patterned hard mask is formed, which surrounds the first patterned hard mask and covers at least a portion of the first doped region. A third doped region is formed in the epitaxial layer by performing a third implantation through the first patterned hard mask and the second patterned hard mask.