Semiconductor device and method for manufacturing the same

A semiconductor device comprising:

• a first contact plug penetrating a source structure;
• 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 a sidewall of the first contact plug, the first spacer including a first portion having a first width and a second portion having a second width that is smaller than the first width;
• and
• a second spacer surrounding the second portion of the first spacer.

A method for manufacturing a semiconductor device, the method comprising:

• forming a sacrificial layer in a source structure;
• forming a first opening that penetrates the source structure;
• forming a first spacer in the first opening;
• forming a first contact plug in the first spacer;
• forming a stack on the source structure;
• forming a second opening that penetrates the stack and exposes the sacrificial layer;
• forming a third opening by removing the sacrificial layer through the second opening;
• and
• forming a second spacer in the third opening.

A method for manufacturing a semiconductor device, the method comprising:

• forming a first insulating spacer that penetrates a source structure to a first depth;
• forming a second insulating spacer that penetrates the source structure to a second depth that is different from the first depth;
• forming a first contact plug in the first insulating spacer;
• forming a stack on the source structure;
• and
• forming a second contact plug that penetrates the stack and is electrically connected to the first contact plug.