A plurality of elongated, substantially parallel mandrels are formed on a first work surface, the mandrels being spaced apart a distance in the range between the resolution limit and twice the resolution limit. Spacers are formed on the work surface extending from sidewalls of the mandrels. First portions of the work surface are exposed through gaps in the spacers near the midpoint between a majority of adjacent mandrels; but at least one pair of adjacent mandrels is close enough together that the spacers extend continuously between the adjacent mandrels. The mandrels are then removed, thereby exposing second portions of the work surface. The exposed first and second portions are etched down to a second work surface; and the exposed portions of the second work surface are etched to form trenches in that surface. A wire routing is formed by filling the trenches with a metal such as copper.