| CPC H01L 29/66068 (2013.01) [H01L 21/0475 (2013.01); H01L 29/7813 (2013.01)] | 5 Claims |
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1. A method for manufacturing a semiconductor device having a plurality of trench gate structures, the method comprising:
preparing a semiconductor substrate having one surface;
arranging a mask on the one surface of the semiconductor substrate;
forming a plurality of opening portions in the mask by patterning the mask so as to expose a plurality of planned formation regions of the semiconductor substrate where a plurality of trenches are to be formed;
forming the plurality of trenches, which extend in a longitudinal direction along a planar direction of the semiconductor substrate, in the semiconductor substrate adjacent to the one surface, by performing a first etching using the mask;
forming a rounded portion at an opening end portion of each of the plurality of trenches by performing a second etching in a state where the mask is arranged and under a condition that a selectivity of the mask is higher than that of the semiconductor substrate; and
arranging a gate insulating film and a gate electrode in each of the plurality of trenches thereby to form the plurality of trench gate structures.
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