Manufacturing method of semiconductor device

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

• forming stacks each including interlayer insulating layers and separated by a slit, the interlayer insulating layers surrounding a channel layer and stacked to be spaced apart from one another with an interlayer space interposed therebetween;
• forming a conductive pattern filling the interlayer space and deviating from the interlayer space;
• and
• forming an isolation layer on a surface of the conductive pattern by oxidizing a portion of the conductive pattern by performing an oxidizing process, wherein a boundary between the isolation layer and a non-oxidized portion of the conductive pattern is disposed within the slit,
• the forming of the conductive pattern comprises:
• forming a first conductive pattern through the slit, the first conductive pattern filling a portion of the interlayer space and surrounding the channel laver;
• and
• forming a second conductive pattern on the first conductive pattern, the second conductive pattern including a first portion filling a remaining portion of the interlayer space and a second portion extending outwardly to an outside of the interlayer space from the first portion,
• wherein the forming of the first conductive pattern comprises:
• forming a first conductive layer through the slit to fill the interlayer space;
• and
• etching the first conductive layer so that the first conductive layer is removed from the slit and remains on a portion of the interlayer space,
• wherein a conductive material remains on edges of the interlayer insulating layers adjacent to the slit during the forming of the first conductive pattern or the second conductive pattern, and
• wherein the conductive material is oxidized in the oxidizing process.