title: Toward Lateral Length Standards at the Nanoscale Based on Diblock Copolymers.
abstract: The self-assembly (SA) of diblock copolymers (DBCs) based on phase separation into different morphologies of small and high-density features is widely investigated as a patterning and nanofabrication technique. The integration of conventional top-down approaches with the bottom-up SA of DBCs enables the possibility to address the gap in nanostructured lateral length standards for nanometrology, consequently supporting miniaturization processes in device fabrication. On this topic, we studied the pattern characteristic dimensions (i.e., center-to-center distance L0and diameter D) of a cylinder-forming polystyrene-b-poly( methyl methacrylate) PS-b-PMMA (54 kg mol-1, styrene fraction 70%) DBC when confined within periodic SiO2trenches of different widths (W, ranging between 75 and 600 nm) and fixed length (l, 5.7 μm). The characteristic dimensions of the PMMA cylinder structure in the confined configurations were compared with those obtained on a flat surface (L0= 27.8 ± 0.5 nm, D = 13.0 ± 1.0 nm). The analysis of D as a function of W evolution indicates that the eccentricity of the PMMA cylinders decreases as a result of the deformation of the cylinder in the direction perpendicular to the trenches. The center-to-center distance in the direction parallel to the long side of the trenches (L0l) is equal to L0measured on the flat surface, whereas the one along the short side (L0w) is subjected to an appreciable variation (ΔL0w= 5 nm) depending on W. The possibility of finely tuning L0wmaintaining constant L0lpaves the way to the realization of a DBC-based transfer standard for lateral length calibration with periods in the critical range between 20 and 50 nm wherein no commercial transfer standards are available. A prototype transfer standard with cylindrical holes was used to calibrate the linear correction factor c(Δx')xx'of an atomic force microscope for a scan length of Δx' = 1 μm. The relative standard uncertainty of the correction factor was only 1.3%, and the second-order nonlinear correction was found to be significant.
authors.affiliation: Nanofacility Piemonte, Istituto Nazionale di Ricerca Metrologica , Strada delle Cacce 91, Torino 10135, Italy.|Dipartimento di Scienze e Innovazione Tecnologica (DIST), Università del Piemonte Orientale "A. Avogadro", INSTM , Viale T. Michel 11, Alessandria 15121, Italy.
authors.forename: Giulia
authors.identifier: http://orcid.org/0000-0001-5926-5140
authors.initials: G
authors.lastname: Aprile
authors.affiliation: Nanofacility Piemonte, Istituto Nazionale di Ricerca Metrologica , Strada delle Cacce 91, Torino 10135, Italy.|Laboratorio MDM, IMM-CNR , Via C. Olivetti 2, Agrate Brianza, MB 20846, Italy.
authors.forename: Federico
authors.identifier: http://orcid.org/0000-0002-1055-8839
authors.initials: F
authors.lastname: Ferrarese Lupi
authors.affiliation: Nanofacility Piemonte, Istituto Nazionale di Ricerca Metrologica , Strada delle Cacce 91, Torino 10135, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Fretto
authors.affiliation: Nanofacility Piemonte, Istituto Nazionale di Ricerca Metrologica , Strada delle Cacce 91, Torino 10135, Italy.
authors.forename: Emanuele
authors.initials: E
authors.lastname: Enrico
authors.affiliation: Nanofacility Piemonte, Istituto Nazionale di Ricerca Metrologica , Strada delle Cacce 91, Torino 10135, Italy.
authors.forename: Natascia
authors.initials: N
authors.lastname: De Leo
authors.affiliation: Nanofacility Piemonte, Istituto Nazionale di Ricerca Metrologica , Strada delle Cacce 91, Torino 10135, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Boarino
authors.affiliation: Laboratorio MDM, IMM-CNR , Via C. Olivetti 2, Agrate Brianza, MB 20846, Italy.
authors.forename: Flavio Giovanni
authors.initials: FG
authors.lastname: Volpe
authors.affiliation: Laboratorio MDM, IMM-CNR , Via C. Olivetti 2, Agrate Brianza, MB 20846, Italy.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Seguini
authors.affiliation: Dipartimento di Scienze e Innovazione Tecnologica (DIST), Università del Piemonte Orientale "A. Avogadro", INSTM , Viale T. Michel 11, Alessandria 15121, Italy.
authors.forename: Katia
authors.initials: K
authors.lastname: Sparnacci
authors.affiliation: Dipartimento di Scienze e Innovazione Tecnologica (DIST), Università del Piemonte Orientale "A. Avogadro", INSTM , Viale T. Michel 11, Alessandria 15121, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Gianotti
authors.affiliation: Dipartimento di Scienze e Innovazione Tecnologica (DIST), Università del Piemonte Orientale "A. Avogadro", INSTM , Viale T. Michel 11, Alessandria 15121, Italy.
authors.forename: Michele
authors.initials: M
authors.lastname: Laus
authors.affiliation: Danish Institute of Fundamental Metrology (DFM) , Matematiktorvet 307, 1. Sal, Kongens Lyngby 2800, Denmark.
authors.forename: Jørgen
authors.initials: J
authors.lastname: Garnæs
authors.affiliation: Laboratorio MDM, IMM-CNR , Via C. Olivetti 2, Agrate Brianza, MB 20846, Italy.
authors.forename: Michele
authors.identifier: http://orcid.org/0000-0001-7431-1969
authors.initials: M
authors.lastname: Perego
keywords: Block copolymer; PS-b-PMMA; directed self-assembly; graphoepitaxy; metrology; thermal annealing; thin film; trench