Double patterning method of patterning a substrate

Abstract

A method of forming a semiconductor device includes forming, over a hardmask layer and an underlying layer of a substrate, a pattern of first trenches between adjacent template lines, each of the first trenches exposing a portion of the hardmask layer, and each of the template lines including a mandrel and spacers on sidewalls of the mandrel; forming a pattern of first blocks over the pattern of the first trenches and the template lines, the first blocks dividing the first trenches to form a pattern of first stencil trenches; transferring the pattern of first stencil trenches to the hardmask layer to form a pattern of first hardmask trenches, each of the first hardmask trenches exposing a portion of the underlying layer; forming a first fill layer filling the first hardmask trenches and exposing the mandrels; selectively removing the mandrels to form second trenches, each of the second trenches exposing a portion of the hardmask layer; and forming a conformal liner in the second trenches and over a surface of the spacers, a surface of the first blocks, and a surface of the first fill layer to form third trenches.