| CPC H10D 64/251 (2025.01) [H01L 23/53257 (2013.01); H10D 64/01 (2025.01); H10D 64/62 (2025.01)] | 14 Claims |

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1. A semiconductor device comprising:
a first contact plug penetrating a source structure, the first contact plug having a first portion having a first width and a second portion having a second width that is larger than the first width;
a stack formed on the source structure and the first contact plug;
a second contact plug penetrating the stack, the second contact plug connected to the first contact plug;
a first spacer surrounding the first portion and the second portion of the first contact plug; and
a second spacer surrounding the first spacer to surround the second portion of the first contact plug.
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