| 摘要 |
A method is provided for forming plural kinds of wells on a single semiconductor substrate with an improved alignment accuracy and obviating the generation of step height between the wells. The method includes forming a selective etching film on the semiconductor substrate, forming openings on the selective etching film overlying a first well forming region and an alignment mark forming region using a first resist film as a mask for defining the first well forming region and the alignment mark forming region, implanting the first well forming region with a dopant of a first conductivity type and removing the first resist film, forming a second resist film to mask at least the first well forming region, having an opening overlying the alignment mark forming region larger than the opening of the selective etching film overlying the same region, and forming the alignment mark by performing an etching process using the second resist film and selective etching film as a mask.
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