Influence Of Additives On The Interfacial Width And Line Edge Roughness In Block Copolymer Lithography

The challenges of patterning next-generation integrated circuits have driven the semiconductor industry to look outside of traditional lithographic methods in order to continue cost-effective size scaling. The directed self-assembly (DSA) of block copolymers (BCPs) is a nanofabrication technique used to reduce the periodicity of patterns prepared by traditional optical methods. BCPs with large interaction parameters (chi(eff)) provide access to smaller pitches and reduced interface widths. Larger chi(eff) are also expected to be correlated with reduced line edge roughness (LER), a critical performance parameter in integrated circuits. One approach to increasing chi(eff) is blending the BCP with a phase-selective additive, such as an ionic liquid (IL). The IL does not impact the etching rates of either phase, and this enables a direct interrogation of whether the change in the interface width driven by higher chi(eff) translates into a lower LER. The effect of the IL on the layer thickness and the interface width of a BCP is examined, along with the corresponding changes in LER in a DSA-patterned sample. The results demonstrate that increased chi(eff) through additive blending will not necessarily translate to a lower LER, clarifying an important design criterion for future material systems.