Method of forming a mask structure and method of forming a minute pattern using the same

A method of forming a minute pattern on a substrate, comprising:

• forming an insulating interlayer on a substrate;
• forming a first mask on the insulating interlayer, the first mask including a first mask pattern having a plurality of mask pattern portions having openings therebetween and a second mask pattern having a corner portion with a curved inner side wall;
• forming a sacrificial layer on the first mask;
• forming a hard mask layer on the sacrificial layer;
• partially removing the hard mask layer until a side wall of the sacrificial layer adjacent to the corner portion is exposed;
• removing the sacrificial layer to form a second mask from the hard mask layer remaining in the opening;
• and
• partially etching the insulating interlayer using the first and the second masks as etching masks to form an insulating interlayer pattern on the substrate.