| 摘要 |
A first impurity region is formed by ion implantation through a first opening formed in a mask layer. By depositing a spacer layer on an etching stop layer on which the mask layer has been provided, a mask portion having the mask layer and the spacer layer is formed. By anisotropically etching the spacer layer, a second opening surrounded by a second sidewall is formed in the mask portion. A second impurity region is formed by ion implantation through the second opening. An angle of the second sidewall with respect to a surface is 90°±10° across a height as great as a second depth. Thus, accuracy in extension of an impurity region can be enhanced.
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