A method of manufacturing a semiconductor device includes: generating a design data of the semiconductor device; and generating a design layout according to the design data. The design layout includes: a first power rail; a second power rail; a first cell including a first first-type active region and a first second-type active region, wherein a first cell height of the first cell is defined as a pitch between the first power rail and the second power rail; a second cell having a second first-type active region and a second second-type active region; and a third cell having a first portion and a second portion arranged in the second row and a fourth row, respectively.