Influence of sidewall affinity on the directed self-assembly for contact hole multiplication

Directed self-assembly of block copolymer (BCP) has been extensively explored in application of contact hole multiplication at the sub-7 nm technology node. The aim of this study is to investigate the effect of surface affinity on the directed self-assembly of BCP, polystyrene-b-poly (methyl methacrylate) (PS-b-PMMA) for contact hole multiplication. The sidewall affinity of the guiding templates for PS and PMMA blocks is manipulated by controlling the grafting process or the PS mole fraction (fPS) of the brushes, which is favorable for tuning the Center-to-Center Distance (CCD) of the twin-hole pattern. The result demonstrates that the CCD increases with increasing the sidewall affinity for PS block of BCP, which is promising to fabricate high-density hole patterns at the sub-7 nm technology node.