A method for defining patterns for conductive paths in a dielectric layer, the method comprising:
- forming a mask layer on the dielectric layer,
- forming on the mask layer a set of longitudinally and parallel extending mask features, each mask feature including mandrels having a pair of side wall spacers, the mask features being spaced apart such that gaps are formed between the mask features,
- depositing an organic spin-on layer covering the set of mask features and filling the gaps,
- etching a first trench in the organic spin-on layer, the first trench extending across at least a subset of the gaps and exposing the mask layer,
- depositing in a spin-on process a planarization layer covering the organic spin-on layer and filling the first trench,
- reducing a thickness of the planarization layer and the organic spin-on layer by etching until upper surfaces of the mask features are exposed, thereby forming, of remaining material of the planarization layer, a discrete first block mask in each gap of the subset of gaps,
- subsequent to reducing the thickness of the planarization layer and the organic spin-on layer:
- depositing an organic spin-on layer covering the set of mask features and each first block mask,
- etching a second trench in the organic spin-on layer, the second trench extending across and exposing at least a subset of mandrels, and further etching each mandrel of the at least a subset of mandrels in the second trench, selective to the organic spin-on layer, to expose the mask layer,
- depositing in a spin-on process a planarization layer covering the organic spin-on layer and filling the second trench,
- reducing a thickness of the planarization layer and the organic spin-on layer by etching until upper surfaces of the mask features are exposed, thereby forming, of remaining material of the planarization layer, a discrete second block mask along each mandrel of the at least a subset of mandrels,
- removing the subset of mandrels, selectively to each second block mask, thereby exposing the mask layer between each pair of side wall spacers, and
- etching the mask layer between each pair of side wall spacers, wherein each second block mask act as an etch mask, thereby forming a second set of trenches in the mask layer, at least one of the trenches being interrupted in a longitudinal direction, wherein a position of the discrete first block mask and a position of the discrete second block mask define intersections for a conductive material,
- removing remaining organic spin-on material between the mask features, selectively to each first block mask, thereby exposing the mask layer in the gaps between the mask features,
- etching the mask layer in the gaps, thereby forming a first set of trenches in the mask layer, at least one of the trenches being interrupted in a longitudinal direction;
- transferring the trenches in the mask layer into the dielectric layer by etching the dielectric layer;
- and
- filling the trenches in the dielectric layer with the conductive material.