| CPC H01L 21/0465 (2013.01) [H10D 12/031 (2025.01); H10D 62/8325 (2025.01)] | 20 Claims |
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1. A method for manufacturing a semiconductor structure, comprising:
forming an epitaxial layer on a semiconductor substrate, and forming a first patterned hard mask on the epitaxial layer, the first patterned hard mask comprising a first opening extending over a first portion of the epitaxial layer;
forming a second patterned hard mask on side surfaces of the first patterned hard mask, the second patterned hard mask together with the first patterned hard mask forming a second opening extending over a second portion of the epitaxial layer that is different from and within the first portion of the epitaxial layer;
forming a first doped region in the second portion of the epitaxial layer by performing a first implantation through the first patterned hard mask and the second patterned hard mask;
forming, in the first portion of the epitaxial layer with the second patterned hard mask removed, a second doped region surrounding the first doped region by performing a second implantation through the first patterned hard mask; and
forming, in the epitaxial layer, a third doped region at a corner of the first doped region by performing a third implantation through the first patterned hard mask; and
wherein the method further comprises: forming a protective layer on the epitaxial layer, wherein the first patterned hard mask is formed on the protective layer exposing a portion of the protective layer through the first opening; and
wherein forming the second patterned hard mask comprises:
forming a second hard mask layer covering the exposed portion of the protective layer and the first patterned hard mask; and
anisotropically etching the second hard mask layer to form the second patterned hard mask, wherein a thickness of the second hard mask layer is less than a thickness of the first patterned hard mask, and a thickness of the second patterned hard mask layer on the side surfaces of the first patterned hard mask gradually increases from top to bottom of the second patterned hard mask layer.
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