Single spacer processes for multiplying pitch by a factor greater than two
are provided. In one embodiment, n, where n.gtoreq.2, tiers of stacked
mandrels are formed over a substrate, each of the n tiers comprising a
plurality of mandrels substantially parallel to one another. Mandrels at
tier n are over and parallel to mandrels at tier n-1, and the distance
between adjoining mandrels at tier n is greater than the distance between
adjoining mandrels at tier n-1. Spacers are simultaneously formed on
sidewalls of the mandrels. Exposed portions of the mandrels are etched
away and a pattern of lines defined by the spacers is transferred to the
substrate.