Methods and structures for enhancing the homogeneity in a ratio of perimeter to surface area among heterogeneous features in different substrate regions. At least one shape on the substrate includes an added edge effective to reduce a difference in the perimeter-to-surface area ratio between the features in a first substrate region and features in a second substrate region. The improved homogeneity in the perimeter-to-surface area ratio reduces variations in a thickness of a conformal layer deposited across the features in the first and second substrate regions.