A method for patterning an underlying layer is described, the method comprising providing a guiding layer on the underlying layer, the guiding layer comprising guiding structures and being substantially planar; providing a block-copolymer layer on the guiding layer; inducing phase separation of the block-copolymer layer in a regular pattern of structures of a first and a second polymer component, whereby one of the components aligns to the guiding structures, by chemo-epitaxy; thereafter, removing a first of the components of the block-copolymer layers completely, leaving a regular pattern of structures of the second component; providing a planarizing layer over the regular pattern of structures of the second component and the guiding layer; removing a portion of the planarizing layer, thereby leaving a regular pattern of structures of the planarizing layer at positions in between the structures of the second component, and exposing the structures of the second component; removing the structures of the second component, selectively with respect to the structures of the planarizing layer; and patterning the underlying layer, thereby using the structures of the planarizing layer as a mask.