Sub‐10 nm Features Obtained from Directed Self‐Assembly of Semicrystalline Polycarbosilane‐Based Block Copolymer Thin Films

Abstract

Highly-ordered arrays with sub-10 nm features are produced with topographical-directed self-assembly of low-molecular-weight poly(1,1-dimethyl silacyclobutane)-block-poly(methyl methacrylate). This system turns out to be of high interest for lithographic applications since the domain orientation is solely controlled through the polymer layer thickness, while the promotion of the microphase separation is obtained by a short thermal annealing process under mild conditions.

Micellar‐Mediated Block Copolymer Ordering Dynamics Revealed by In Situ Grazing Incidence Small‐Angle X‐Ray Scattering during Spin Coating

“…As already mentioned above, the lamellar morphology is not expected at equilibrium since a cylindrical structure is produced from thermally annealed PDMSB ‐b ‐PMMA samples (see Figure A) in accordance with the BCP composition in the dry state ( f PDMSB = 0.72) and previous data . From the thermodynamic point of view, this discrepancy can be explained by considering the selective location of the high boiling PGMEA solvent inside the minor PMMA domains (PDMSB homopolymer chains show a low solubility in PGMEA), thus altering the phase diagram and shifting the structure from cylindrical to lamellar morphology.…”

“…In this work, in situ GISAXS measurements were performed to monitor the structural development of parallel lamellae formed by poly(1,1‐dimethyl silacyclobutane)‐ block ‐poly(methyl methacrylate) (PDMSB‐ b ‐PMMA) thin films spin coated from a BCP solution in a mixture of two solvents, one common for the two blocks and one selective for only one block. Although the directed self‐assembly of these PDMSB‐ b ‐PMMA chains into a thin film cylindrical structure has been demonstrated at equilibrium (i.e., through thermal annealing treatment), the complex thermodynamic interactions between the different blocks and the solvent mixture, consisting of high and low boiling point solvents, yield to the formation of highly ordered in‐plane lamellae after the spin coating process. Controlling and stabilizing with high reproducibility a certain morphology characterized by an excellent long‐range order is of key importance for BCP nanotechnology and, through this study, we sought to better apprehend the mechanisms leading to segregated structures and acting during the spin coating process.…”

Polymer Interfaces: Synthetic Strategies Enabling Functionality, Adaptivity, and Spatial Control

“…Clearly, one limitation is that for microphase separation to occur, certain molecular weights of the underlying block copolymers are required; hence, feature sizes of less than 10 nm usually are challenging and identified (see below) as a key issue. One possibility to circumvent the molecular weight aspect is the use of systems with a strong tendency to segregate (high χ systems) 45 such as polystyrene- 49 In addition, the use of prepatterned substrates can further decrease feature sizes in block copolymer self-assembly, as could be shown by Russell and co-workers for PS-b-PEO features on sapphire (α-Al 2 O 3 ) substrates with size regimes from 13 down to 3 nm ( Figure 2). 50 Whereas many other examples could be listed addressing resolution or morphological variability, interface design additionally requires the development of site-selective chemistry within such materials.…”

Technological strategies for self-assembly of PS-b-PDMS in cylindrical sub-10 nm nanostructures for lithographic applications

“…The size of the nanostructures depends to the molecular weight of the BCPs. Proper design of BCP characteristics allows nanostructured polymeric films with characteristic dimensions below 10 nm to be obtained [18]. In addition, BCP-based lithography can be easily integrated in existing microelectronics production lines [5,19,20].…”