Methods of forming non-volatile memory device

A method of forming a non-volatile memory device, the method comprising:

• forming first mask patterns on an etching target layer that is on a substrate, the first mask patterns including a source mask line, a string select mask line, and a plurality of first cell mask lines disposed between the source mask line and the string select mask line;
• forming a distance regulating layer that conformally covers the first mask patterns and defines grooves thereon that are between and extend parallel to adjacent pairs of the first mask patterns;
• forming second mask patterns in the grooves between the first mask patterns, the second mask patterns including a ground select mask line in a groove adjacent to the source mask line and a plurality of second cell mask lines each in one of another grooves adjacent to the first cell mask lines;
• anisotropically etching the distance regulating layer on both sides of the ground select mask line, the string select mask line, the first cell mask lines, and the second cell mask lines to expose portions of the etching target layer;
• and
• patterning the etching target layer using the ground select mask line, the string select mask line, the first cell mask lines, and the second cell mask lines as etch masks to form a ground select gate line, a string select gate line, and a plurality of cell gate lines, respectively.