A method of avoiding substrate noise in an integrated circuit includes steps of receiving as input an integrated circuit design that includes at least a portion of a block for placement and routing on a substrate and an outer boundary of the block. An end cell is selected from a set of end cells for terminating the block in an outer area that extends from the outer boundary to an end cell boundary outside the block. The selected end cell is placed in the outer area to isolate the block electrically from the substrate.