A method that provides patterning of an underlying layer to form a first set of trenches and a second set of trenches in the underlying layer is based on a combination of two litho-etch (LE) patterning processes supplemented with a spacer-assisted (SA) technique. The method uses one or more first upper blocks formed by a tone-inversion approach, an upper memorization layer allowing first memorizing upper trenches, and then second upper blocks, and a lower memorization layer allowing first memorizing first lower trenches and one or more first lower blocks, and then second lower trenches and one or more second lower blocks.