Stacked memory device, optical proximity correction (opc) verifying method, method of designing layout of stacked memory device, and method of manufacturing stacked memory device

A method of manufacturing a stacked memory device, the method comprising:

• designing a layout of the stacked memory device;
• calculating a shift value of a first pattern according to a first location of the first pattern in the layout;
• obtaining a difference value between the first location and a second location of a second pattern formed through a first OPC with respect to the first pattern;
• determining whether a second OPC is to be performed, based on the shift value and the difference value;
• forming a mask, based on the second pattern or a third pattern formed through the second OPC;
• and
• forming the stacked memory device through a lithographic process using the mask.