Patterning a target layer

A method for patterning a target layer, the method comprising:

• forming above the target layer a line mask and a mandrel mask and a buffer layer, wherein forming the line mask comprises forming parallel material lines extending in a longitudinal direction, wherein forming the mandrel mask comprises forming the mandrel mask above the buffer layer, the mandrel mask having sidewalls comprising at least a first sidewall extending transverse to a plurality of the parallel material lines;
• forming, on the sidewalls of the mandrel mask, a sidewall spacer comprising a first sidewall spacer portion extending along the first sidewall;
• removing the mandrel mask;
• transferring a pattern defined by the sidewall spacer into the buffer layer, thereby forming a patterned buffer layer;
• partially removing the patterned buffer layer such that a remainder of the patterned buffer layer comprises at least one part that extends transverse to the plurality of the parallel material lines;
• and
• transferring into the target layer a pattern defined by the line mask and the at least one transversely extending part.