A method including creating a plurality of component groups in a circuit layout coupling multiple components in each component group of the plurality of component groups with a power rail, a ground rail, or a bulk, is provided. The method includes creating internal clusters based on a group cost and including the group cost in an overall cost function, forming a gap between two component groups of the plurality of component groups, and filling the gap with a first gap cell adjacent to a first power rail and to a first ground rail, and a second gap cell adjacent to the first gap cell. A system and a non-transitory, machine readable medium storing instructions to perform the above method are also provided.