A system and method for reducing density mismatch is disclosed. An embodiment comprises determining a conductor density and an active area density in a high density area and a low density area of a semiconductor device. Dummy material may be added to the low density area in order to raise the conductor density and the active area density, thereby reducing the internal density mismatches between the high density area and the low density area. Additionally, a similar process may be used to reduce external mismatches between different regions on the semiconductor substrate. Once these mismatches have been reduced, empty regions surrounding the different regions may additionally be filled in order to reduce the conductor density mismatch and the active area density mismatches.