A semiconductor device and a method of manufacturing a semiconductor device pertain to a semiconductor device having a channel pillar extending in a first direction and a first conductive pattern surrounding the channel pillar. The semiconductor device also has second conductive patterns surrounding the channel pillar above the first conductive pattern, wherein the second conductive patterns are stacked in the first direction and spaced apart from each other. The semiconductor device further has an etch stop pattern disposed above the first conductive pattern and below the second conductive patterns.