According to some embodiments, the height S1 of the third portion 310c may be greater than the height S. The height S1 may be a total of n*S and m*T, wherein n is an integer not less than 2, and m is an integer not less than 1. For example, the height S1 may be a total of 2*S and 1*T. In this example, the height S1 is substantially equal to a total of the heights S of two standard cell structure 304 and the height of one standard cell structure 306.