Methods of reducing defects in directed self-assembled structures

A method of reducing the number of defects in a directed self-assembled structure formed on a guiding pre-pattern on a substrate, the method comprising:

• applying a first layer comprising a first self-assembly material onto the guiding pre-pattern, the first self-assembly material forming domains whose alignment and orientation are directed by the guiding pre-pattern, thereby creating a first self-assembled structure;
• washing away the first self-assembled structure;
• and
• after said washing, applying a second layer comprising a second self-assembly material over the substrate, wherein the second layer occupies space previously occupied by the first layer, the second self-assembly material forming a second self-assembled structure having fewer defects than the first self-assembled structure.