Method for defining patterns for conductive paths in dielectric layer

A method for defining patterns for conductive paths in a dielectric layer, the method comprising:

• forming a mask layer above the dielectric layer;
• forming above the mask layer a set of mandrels, each mandrel having a pair of side wall spacers;
• etching the mask layer, wherein the set of mandrels and the pairs of side wall spacers act as an etch mask, to form a first set of trenches in the mask layer;
• covering the set of mandrels with a metal oxide planarization layer, the metal oxide planarization layer filling the first set of trenches;
• etching back the metal oxide planarization layer to expose upper surfaces of the set of mandrels;
• removing the set of mandrels by etching, thereby forming trenches in the metal oxide planarization layer, the trenches in the metal oxide planarization layer extending between the pairs of side wall spacers;
• forming a block mask extending across at least a subset of the trenches in the metal oxide planarization layer;
• and
• etching the mask layer, wherein the metal oxide planarization layer and the block mask act as an etch mask during the etching of the mask layer to form a second set of trenches, wherein the block mask counteracts removal of a portion of the mask layer along at least a subset of the second set of trenches.

A method for defining patterns for conductive paths in a dielectric layer, the method comprising:

• forming a mask layer above the dielectric layer;
• forming above the mask layer a set of mandrels, each mandrel having a pair of side wall spacers;
• forming a first block mask extending across at least a subset of the set of mandrels;
• etching the mask layer, wherein the set of mandrels and the pairs of side wall spacers act as an etch mask, to form a first set of trenches in the mask layer, wherein the first block mask counteracts removal of a portion of the mask layer along at least a subset of the first set of trenches;
• covering the set of mandrels with a metal oxide planarization layer, the metal oxide planarization layer filling the first set of trenches;
• etching back the metal oxide planarization layer to expose upper surfaces of the set of mandrels;
• removing the set of mandrels by etching, thereby forming trenches in the metal oxide planarization layer, the trenches in the metal oxide planarization layer extending between the pairs of side wall spacers;
• forming a second block mask extending across at least a subset of the trenches in the metal oxide planarization layer;
• and
• etching the mask layer, wherein the metal oxide planarization layer acts as an etch mask, to form a second set of trenches in the mask layer, wherein the second block mask counteracts removal of a portion of the mask layer along at least a subset of the second set of trenches.