High chi block copolymer (bcp) pattern on latent extreme ultraviolet (euv) images

A method for patterning an exposed polarity switching layer that is over a substrate, wherein the exposed polarity switching layer comprises an exposed region and an unexposed region, the method comprising:

• applying a first block copolymer over the polarity switching layer, wherein the first block copolymer comprises a first polar region and a first non-polar region with a first pitch, and wherein a chemical difference between the exposed region of the polarity switching layer and the unexposed region of the polarity switching layer allows for directed self-assembly of the first non-polar region and the first polar region at the first pitch;
• selectively removing either the first polar region or the first non-polar region to form a first patterned mask over the polarity switching layer;
• patterning the polarity switching layer with an etching process using the first patterned mask;
• applying a polymer brush in an opening through the polarity switching layer and the first patterned mask;
• applying a second block copolymer over the first block copolymer and the polymer brush, wherein the second block copolymer is annealed to drive directed self-assembly of a second polar region and a second non-polar region with a second pitch that is smaller than the first pitch;
• and
• removing the second polar region or the second non-polar region to form a second patterned mask over the polarity switching layer.

A method, comprising:

• exposing a polarity switching layer with extreme ultraviolet (EUV) radiation to form an exposed region and an unexposed region, wherein the polarity switching layer has a thickness that is less than 25 nm;
• applying a block copolymer over the polarity switching layer;
• annealing a portion of the block copolymer with a laser to allow for a directed self-assembly process of the portion of the block copolymer to segregate a polar region of the block copolymer from a non-polar region of the block copolymer, wherein the exposed region and the unexposed region have chemical differences that provide a template to enable the directed self-assembly process;
• removing the polar region or the non-polar region to form a patterned mask over the polarity switching layer;
• and
• etching the polarity switching layer to form a patterned polarity switching layer using the patterned mask.