(417i) Evaluation of Three-Dimensional Line-Edge Roughness of Pre-and Post-Dry Etched Line and Space Patterns of Block-Copolymer Lithography
In this talk, we will focus on the comparative study of the experimental LER / LWR calculations with our coarse-grained molecular dynamics (CGMD) simulation results. In our recent work, we have outlined our CGMD framework and subsequent etching methodology used to form thin-film line and space patterns created by symmetric polystyrene-block-polymethyl methacrylate (PS-b-PMMA) with periods of about 28 nm, on a patterned Liu-Nealey (LiNe) flow substrate. The defect free lamellae patterns in this study were etched using a wet etching schematic which have been experimentally observed to favor patterns collapse especially at lower BCP film thicknesses. In an effort to closely match the experimental conditions, we have developed a novel dry-etching simulation methodology to study the selective removal of PMMA with O2/Ar etch chemistry. Subsequently, we perform a three-dimensional edge detection on the resist domains (PS) to evaluate the LER and LWR and compare it with the pre-etched BCP interfacial fluctuations. In addition to the default etching, we also evaluate roughness contribution of only the etching process by kinetically freezing the BCP beads, thereby nullifying the post-etch polymer relaxation. The roughness evaluation is done both in the space as well as Fourier domains for a more accurate understanding of the low and high frequency contributions of the deviations. Strategies in the form of short-chained polymeric additives, that are resistive to O2/Ar etch chemistry and thermodynamically prefer to self-assemble at the BCP interface are assessed. The efficacy of these additive to protect the BCP interface from the etch-ions is studied by examining their edge roughness. Lastly, we compare our simulation results to experimental SEM images of equivalent line and space patterns using an in-house image processing code.