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Directed self-assembly (DSA) of block copolymers (BCP) is one of the most promising patterning solutions for sub-10 nm nodes. While significant achievements are demonstrated in pattern fidelity for various applications (contact shrink, line patterning), some challenges are still needed to be overcome especially regarding the defect density reduction, in order to ensure DSA insertion in high-volume manufacturing. In particular, in the case of the graphoepitaxy approach, a remaining challenge is to solve the pattern-densities-related defect issue due to BCP film thickness variation inside the guiding template. In order to address this issue, a new DSA process flow called 'DSA planarization' is employed for contact-hole patterning, and consists in overfilling the guiding pattern cavities with a thick BCP film, followed by a plasma etch-back step. This new approach ensures a uniform control of the final thickness of the BCP inside guiding cavities of different densities, as demonstrated herein by AFM measurement. Thus, defect-free isolated and dense patterns for both contact shrink and multiplication are simultaneously resolved. Furthermore, the simulation results of BCP self-assembly overfilling the templates demonstrate that BCP domains are well-directed in vertical cylinders ordering inside guiding cavities, which confirms the experimental results and the viability of this approach. [ABSTRACT FROM AUTHOR]

Theself-assembly of polystyrene-block-poly(methylmethacrylate) (PS-b-PMMA) copolymer (BCP) films,leading to hexagonal arrays of perpendicular PMMA cylinders in a PSmatrix, and its ordering kinetics were investigated using ex situand in situ grazing incidence small-angle X-ray scattering (GISAXS).The ex situ measurements have provided accurate information aboutthe structural changes in self-assembled BCP films with multiple processingparameters (PMMA removal process, film thickness, annealing treatment).Such structural information proves essential since BCP films are envisionedas template materials for density multiplication in nanolithography.Moreover, the temperature-dependent GISAXS measurements indicate thatphase-separation starts around 140 °C and annealing up to 240°C is required to form homogeneous self-assembled films withinthe short baking times required by industry. Furthermore, the guidingeffect of an hydrogen silsesquioxane (HSQ) line grating commensurablewith the polymer period on self-assembly (the so-called graphoepitaxyapproach) was studied on silicon wafers presenting jointly patternedand unpatterned areas. When the line grating is aligned with the directionof the incident X-ray beam, the GISAXS pattern of the graphoepitaxialBCP film reveals the formation of a single domain extended over largeareas. In contrast, the pattern of the BCP film self-assembled onthe neighbor unpatterned area, comes from randomly oriented domains.Besides, the line grating does not only guide the BCP self-assembly,but as shown, also increases its ordering kinetics, demonstratingthe high potentialities of graphoepitaxy. [ABSTRACT FROM AUTHOR]