Patent ID: 8222140

Claim:
A method comprising: depositing a first spacer layer on a first set of spacers to form a first pattern of lines having a lateral dimension of 3 F separated by a 1 F space included on a patterning stack, wherein 1 F is a first final feature size and 3 F is a second size three times the size of 1 F, the patterning stack to further include a hard mask layer, a first etch-stop layer, a second etch-stop layer, and a bulk layer; transferring the first pattern to the hard mask layer; for each of the 1 F spaces separating the lines of the first pattern, performing an etch into the bulk layer of the patterning stack to create a first set of trenches; removing the remaining hard mask layer and filling each of the first set of trenches with a filling material; removing the first etch-stop layer to expose the filled first set of trenches; depositing a second spacer layer on the exposed first set of filled trenches to form a third pattern of lines having a lateral dimension of 3 F separated by a 1 F space; for each of the 1 F spaces separating the lines of the third pattern, performing an etch into the bulk layer of the patterning stack to create a second set of trenches; and filling each of the second set of trenches with the filling material to form a fourth pattern of lines comprising the first and second set of filled trenches, wherein lines of the fourth pattern comprise a lateral dimension of 1 F separated by a 1 F space.