Patent ID: 7361435

Claim:
A method of creating a layout of a set of masks, the method comprising: reading layout data of an interconnection line that has a large line width; identifying an area from the read layout data in which an access interconnection line is formed by destructive light interference to have a line width smaller than the large line width; creating a layout of an alternating phase shifting mask (APSM) having first and second phase shifting areas based on the identification, the first and second phase shifting areas having different phases and being disposed adjacent to each other to generate the destructive light interference; and creating a layout of a halftone phase shifting trim mask (HPSTM) that has an opaque pattern to prevent the access interconnection line defined by the APSM from being erased, and a halftone pattern defining a pass interconnection line, which has a line width smaller than the large line width and is connected to the access interconnection line, wherein the line width of the pass interconnection line is no greater than that of the access interconnection line.