Semiconductor devices

A semiconductor device comprising:

• a first slit disposed at a boundary between contiguous memory blocks to isolate the memory blocks from each other, and including a first outer slit and a second outer slit, the second outer slit spaced apart in a first direction from the first outer slit by a predetermined distance;
• a word line disposed, between the first and second outer slits, including a center region having a first end and a second end, and an edge region located at the first end and the second end of the center region;
• a second slit disposed at the center region that isolates areas of the word line in the center region on either side of the second slit;
• a plurality of drain selection lines disposed between the first and second outer slits, and disposed to be spaced apart from each other by a predetermined distance with respect to the first direction;
• and
• a first isolation pattern that isolates each of a first drain selection line and a second drain selection line from among the plurality of drain selection lines,
• wherein the word line is continuous in the edge regions.