A method of forming a semiconductor structure includes forming a dielectric layer, forming a plurality of mandrel lines over the dielectric layer, and forming a plurality of non-mandrel lines over the dielectric layer between adjacent ones of the mandrel lines utilizing self-aligned double patterning. The method also includes forming at least one spacer-merge region extending from a first portion of a first one of the mandrel lines to a second portion of a second one of the mandrel lines in a first direction and covering at least a portion of one or more of the non-mandrel lines between the first mandrel and the second mandrel in a second direction orthogonal to the first direction. The method further includes forming a plurality of trenches in the dielectric layer by transferring a pattern of (i) the mandrel lines and (ii) portions of the non-mandrel lines outside the at least one spacer-merge region.