separate however it will be appreciated that for other bcps or other resists this ratio may be different the self assemblable a b block copolymer may have hydrophilic a block unhatched and hydrophobic b block hatched the hydrophobic b block has a high affinity for the sidewall of the recess whereas the hydrophilic a block has a high affinity for other a block therefore during the annealing process the ordered layer of bcp has formed with cylindrical domains of hydrophilic a block surrounded by domains of b block which are in contact with the recess sidewall in subsequent processing steps not shown domains of a block 16 can be selectively removed by any technique such selective removal of a block domains 16 exposes the substrate 10 below the a block domains 16 however b block domains 17 will not be removed by the process which removed the a block domains 16 due to the selectivity of the etching process further the bcp material in the dummy recesses 13 which has not formed discrete a and b block domains will not be removed by the type a selective etch process in this way it is possible to remove only regions of type a polymer with all other areas of the substrate 10 being covered by either b.