Al₂O₃ Dot and Antidot Array Synthesis in Hexagonally Packed Poly(styrene-block-methyl methacrylate) Nanometer-Thick Films for Nanostructure Fabrication

Abstract

Nanostructured organic templates originating from self-assembled block copolymers (BCPs) can be converted into inorganic nanostructures by sequential infiltration synthesis (SIS). This capability is particularly relevant within the framework of advanced lithographic applications because of the exploitation of the BCP-based nanostructures as hard masks. In this work, Al 2 O 3 dot and antidot arrays were synthesized by sequential infiltration of trimethylaluminum and water precursors into perpendicularly oriented cylinder-forming poly(styrene- block -methyl methacrylate) (PS- b -PMMA) BCP thin films. The mechanism governing the effective incorporation of Al 2 O 3 into the PMMA component of the BCP thin films was investigated evaluating the evolution of the lateral and vertical dimensions of Al 2 O 3 dot and antidot arrays as a function of the SIS cycle number. The not-reactive PS component and the PS/PMMA interface in self-assembled PS- b -PMMA thin films result in additional paths for diffusion and supplementary surfaces for sorption of precursor molecules, respectively. Thus, the mass uptake of Al 2 O 3 into the PMMA block of self-assembled PS- b -PMMA thin films is higher than that in pure PMMA thin films.

Sequential Infiltration Synthesis of Al2O3 in Biodegradable Polybutylene Succinate: Characterization of the Infiltration Mechanism

“…For polymer having the reactive group on the main polymeric chain, incorporation of the inorganic phase implies a progressive degradation of the mechanical properties of the final hybrid organic–inorganic material. From another point of view, present results suggest that PBS could represent an effective polymer matrix for the incorporation of alumina and the formation of Al 2 O 3 nanostructures when used as a block in a self-assembled di- or ter-block copolymer template like in the case of a more conventional PS- b -PMMA system . Incorporation of alternative metal oxides could be explored as an alternative solution to further improve the UV shielding properties of the PBS films.…”

“…From another point of view, present results suggest that PBS could represent an effective polymer matrix for the incorporation of alumina and the formation of Al 2 O 3 nanostructures when used as a block in a self-assembled di- or ter-block copolymer template like in the case of a more conventional PS- b -PMMA system. 55 Incorporation of alternative metal oxides could be explored as an alternative solution to further improve the UV shielding properties of the PBS films. Proper selection of the titanium precursor could guarantee the possibility to infiltrate into the PBS matrix operating at low temperature; nevertheless the effective capability to improve the optical properties of this polymer is questionable, because the amount of TiO 2 incorporated into the PBS has to be limited in order to avoid significant degradation of its thermal and mechanical properties.…”

Al2O3 growth in PMMA thin films by sequential infiltration synthesis: in situ thickness evolution and mass uptake investigation

“…Depending on the specific morphology of the block copolymer template different inorganic nanostructures can be obtained, providing a simple and cost-effective tool to generate periodic inorganic nanostructures over large areas. [15][16][17][18] A theoretical framework for the description of this process has been outlined in a couple of seminal papers by Leng and Losego, 7,19 providing a first indication of the different phenomena taking place during a SIS process. However, several fundamental aspects of the SIS process are not fully understood yet.…”

Periodic Arrays of Dopants in Silicon by Ultralow Energy Implantation of Phosphorus Ions through a Block Copolymer Thin Film

“…Surprisingly, to the best of our knowledge, the possibility to use those nanostructured polymeric films as a soft mask to promote local modification of the substrate by conventional ion implantation has not been investigated in detail. In this respect, the poor resistance of polymers to ion bombardment and the limited thickness of these polymer films represent severe limitations and usually relegates those polymer templates to the role of patterning tool for the preparation of hard masks − that are subsequently used during the ion implantation process. Alternatively, ultralow energy ( E < 5 keV) ion implantation represents a viable solution to overcome those limitations.…”