Enabling chemically amplified resists towards tight pitch EUV patterning by directed self-assembly

Combining directed self-assembly (DSA) with chemically amplified resists (CARs) can boost the effectiveness of CARs for tight pitch extreme ultraviolet (EUV) lithography patterning. The objective of this work is to optimize the obtained DSA patterns after etching the block-copolymer (BCP) structures into an appropriate stack. For pitch 24 nm line/space patterns, it is found that a SiCN/amorphous carbon bilayer underneath the DSA film is best suited to minimize the occurrence of line wiggling during pattern transfer. A further reduction of line width roughness is obtained by using a high-chi BCP material. Next, it is shown that thicker BCP films are effective to improve the pattern placement accuracy of a pitchC2C 30 nm PS-b-PMMA hexagonal contact hole pattern. Furthermore, the use of a high-chi BCP material is found to bring substantial improvement to the pattern uniformity and placement accuracy of the contact hole array.