A method of forming a gate layout includes providing a gate layout design diagram comprising at least one gate pattern, disposing at least one insulating plug pattern in the gate pattern for producing a modified gate layout in a case where any one of a length and a width of the gate pattern is greater than or equal to a predetermined size, and outputting and manufacturing the modified gate layout onto a photomask. The predetermined size is determined by a process ability limit, and the process ability limit is a smallest gate size causing gate dishing when a chemical mechanical polishing process is performed to a gate.