Directed self-assembly material etch mask for forming vertical nanowires

A method, comprising:

• forming at least one fin on a semiconductor substrate;
• forming an insulating layer surrounding at least a portion of said at least one fin;
• forming a recess in said at least one fin and in said insulating layer;
• forming a nanowire material in said recess;
• forming a hard mask layer in said recess above said nanowire material;
• forming a first directed self-assembly material in said recess above said hard mask layer;
• annealing said first directed self-assembly material to define an etch-resistant component and an etchable component;
• removing said etchable component to expose a portion of said hard mask layer;
• patterning said hard mask layer using said etch-resistant component as an etch mask to expose a portion of said nanowire material;
• and
• etching said nanowire material using said hard mask layer as an etch mask to define a substantially vertical nanowire on a top surface of said at least one fin having a first long axis extending in a direction perpendicular to a second long axis of said at least one fin, wherein at least one dimension of said substantially vertical nanowire is defined by an intrinsic pitch of said first directed self-assembly material.