A method for defining routing tracks to be formed in a target layer above a standard cell semiconductor device, the method comprising: forming a first mandrel , a second mandrel and a third mandrel above the target layer , the second mandrel being arranged between the first mandrel and the third mandrel ; providing a first spacer material on at least part of the sidewalls of said mandrels , thereby forming a first set of spacers including at least a first spacer on a sidewall of the first mandrel , said sidewall facing the second mandrel , a second and a third spacer on the second mandrel , and at least a fourth spacer on a sidewall of the third mandrel , said sidewall facing the second mandrel ; removing said mandrels ; transferring said first set of spacers into a dummy layer arranged between the target layer and the first set of spacers, thereby forming a set of dummy features including a first, second, third and fourth dummy feature corresponding to said first, second, third and fourth spacer , wherein said set of dummy features defines positions of off-centre routing tracks (T1, T2, T3, T4); providing a second spacer material on at least part of the sidewalls of said set of dummy features, thereby forming a second set of spacers , wherein spacers of said second set of spacers fill a gap between said first and second dummy feature and a gap between said third and fourth dummy feature , and leave a gap between said second and third dummy feature , said gap defining a position of a central routing track (T5); providing a filler material in said gap ; removing said second set of spacers; patterning said filler material and said set of dummy features; and patterning the target layer using said patterned filler material and said set of dummy features as a mask. forming a first mandrel , a second mandrel and a third mandrel above the target layer , the second mandrel being arranged between the first mandrel and the third mandrel ; providing a first spacer material on at least part of the sidewalls of said mandrels , thereby forming a first set of spacers including at least a first spacer on a sidewall of the first mandrel , said sidewall facing the second mandrel , a second and a third spacer on the second mandrel , and at least a fourth spacer on a sidewall of the third mandrel , said sidewall facing the second mandrel ; removing said mandrels ; transferring said first set of spacers into a dummy layer arranged between the target layer and the first set of spacers, thereby forming a set of dummy features including a first, second, third and fourth dummy feature corresponding to said first, second, third and fourth spacer , wherein said set of dummy features defines positions of off-centre routing tracks (T1, T2, T3, T4); providing a second spacer material on at least part of the sidewalls of said set of dummy features, thereby forming a second set of spacers , wherein spacers of said second set of spacers fill a gap between said first and second dummy feature and a gap between said third and fourth dummy feature , and leave a gap between said second and third dummy feature , said gap defining a position of a central routing track (T5); providing a filler material in said gap ; removing said second set of spacers; patterning said filler material and said set of dummy features; and patterning the target layer using said patterned filler material and said set of dummy features as a mask. <EOS>