Photomask including line pattern monitoring mark and method of manufacturing integrated circuit device using the same

A method of manufacturing an integrated circuit device, the method comprising:

• forming a plurality of monitoring line patterns on a substrate by performing an exposure process using a photomask that includes at least one line pattern monitoring mark having a plurality of unit blocks that comprise a plurality of design line patterns, the plurality of design line patterns being arranged at a constant pitch along a first horizontal direction;
• determining a position of a design cut line extending through at least two design line patterns from the plurality of design line patterns in the first horizontal direction;
• and
• determining a line end profile error in a plurality of monitoring line patterns based on a cross-sectional structure of the plurality of monitoring line patterns taken along a cut line extending through at least a portion of the plurality of monitoring line patterns in the first horizontal direction,
• wherein a position of the cut line corresponds to the position of the design cut line,
• wherein each of the plurality of unit blocks comprises three design line patterns from the plurality of design line patterns, and adjacent ones of the plurality of unit blocks are offset from each other in a second horizontal direction perpendicular to the first horizontal direction, and
• wherein the plurality of unit blocks comprise a first unit block and a second unit block adjacent to the first unit block in the first horizontal direction, the second unit block being offset from the first unit block by a rounding length in the second horizontal direction, and the second unit block being spaced apart from the first unit block in the first horizontal direction.