Quantification of nanomechanical properties of surfaces by higher harmonic monitoring in amplitude modulated AFM imaging

Altres ajuts: the ICN2 is funded by the CERCA programme/Generalitat de Catalunya.The determination of nanomechanical properties is an intensive topic of study in several fields of nanophysics, from surface and materials science to biology. At the same time, amplitude modulation force microscopy is one of the most established techniques for nanoscale characterization. In this work, we combine these two topics and propose a method able to extract quantitative nanomechanical information from higher harmonic amplitude imaging in atomic force microscopy. With this method it is possible to discriminate between different materials in the stiffness range of 1-3 GPa, in our case thin films of PS-PMMA based block copolymers. We were able to obtain a critical lateral resolution of less than 20 nm and discriminate between materials with less than a 1 GPa difference in modulus. We show that within this stiffness range, reliable values of the Young's moduli can be obtained under usual imaging conditions and with standard dynamic AFM probes

Role of penetrability into a brush-coated surface in directed self-assembly of block copolymers

Altres ajuts: the ICN2 is funded by the CERCA programme/Generalitat de Catalunya.High-density and high-resolution line and space patterns on surfaces are obtained by directed self-assembly of lamella-forming block copolymers (BCPs) using wide-stripe chemical guiding patterns. When the width of the chemical pattern is larger than the half-pitch of the BCP, the interaction energy between each BCP domain and the surface is crucial to obtain the desired segregated film morphology. We investigate how the intermixing between BCPs and polymer brush molecules on the surface influences the optimal surface and interface free energies to obtain a proper BCP alignment. We have found that computational models successfully predict the experimentally obtained guided patterns if the penetrability of the brush layer is taken into account instead of a hard, impenetrable surface. Experiments on directed self-assembly of lamella-forming poly(styrene-block-methyl methacrylate) using chemical guiding patterns corroborate the models used in the simulations, where the values of the surface free energy between the BCP and the guiding and background stripes are accurately determined using an experimental method based on the characterization of contact angles in droplets formed after dewetting of homopolymer blends

Nanomechanical properties of solvent cast polystyrene and poly(methyl methacrylate) polymer blends and self-assembled block copolymers

© 2015 Society of Photo-Optical Instrumentation Engineers (SPIE). The nanomechanical properties of solvent-cast polymer thin films have been investigated using PeakForce™ Quantitative Nanomechanical Mapping. The samples consisted of films of polystyrene (PS) and poly(methyl methacrylate) (PMMA) obtained after the dewetting of toluene solution on a polymeric brush layer. Additionally, we have probed the mechanical properties of poly(styrene-b-methyl methacrylate) block copolymers (BCP) as randomly oriented thin films. The probed films have a critical thickness <50 nm and present features to be resolved <42 nm. The Young's modulus values obtained through several nanoindentation experiments present a good agreement with previous literature, suggesting that the PeakForce™ technique could be crucial for BCP investigations, e.g., as a predictor of the mechanical stability of the different phases.This work was partially funded by the projects SNM (FP7-ICT-2011-8) and FORCE-for-FUTURE (CSD2010-00024).Peer Reviewe

In situ real-time characterization of block copolymer self-assembly processes by GISAXS

E-MRS Spring Meeting and Exhibit will be held in the Convention Centre of Strasbourg (France), from June 18 to 22 (2018). .--https://www.european-mrs.com/block-copolymer-self-assembly-fundamentals-and-applications-emr

Extracting Block Copolymer Dynamics from GISAXS

4th. International symposium on DSA.(2018)4th. International symposium on DSA. 11-13. November, 2F Pearl Room, Sapporo Park Hotel. Japan (2018) .-http://dsasymp.org/program.htm

Identifying the nature of surface chemical modification for directed self-assembly of block copolymers

The license is subject to the Beilstein Journal of Nanotechnology terms and conditions: http://www.beilstein-journals.org/bjnanoIn recent years, block copolymer lithography has emerged as a viable alternative technology for advanced lithography. In chemical-epitaxy-directed self-assembly, the interfacial energy between the substrate and each block copolymer domain plays a key role on the final ordering. Here, we focus on the experimental characterization of the chemical interactions that occur at the interface built between different chemical guiding patterns and the domains of the block copolymers. We have chosen hard X-ray high kinetic energy photoelectron spectroscopy as an exploration technique because it provides information on the electronic structure of buried interfaces. The outcome of the characterization sheds light onto key aspects of directed self-assembly: grafted brush layer, chemical pattern creation and brush/block co-polymer interface

26th Annual Computational Neuroscience Meeting (CNS*2017): Part 3 - Meeting Abstracts - Antwerp, Belgium. 15–20 July 2017

This work was produced as part of the activities of FAPESP Research,\ud Disseminations and Innovation Center for Neuromathematics (grant\ud 2013/07699-0, S. Paulo Research Foundation). NLK is supported by a\ud FAPESP postdoctoral fellowship (grant 2016/03855-5). ACR is partially\ud supported by a CNPq fellowship (grant 306251/2014-0)

Directed self-assembly of block copolymers on chemically nanopatterned surfaces

La tesi doctoral titulada “Auto-assemblatge de copolímers de bloc per modificació química de la superfície”, presenta com a objectiu principal el desenvolupament, implementació i caracterització d’un mètode de guiatge de copolímers de bloc basat en la modificació química de la superfície. El desenvolupament d’aquest mètode de nanofabricació contribueix a la futura generació de dispositius i circuits nanoelectrònics. Primer de tot, es presenten els aspectes generals sobre l’auto-assemblatge dirigit de copolímers de bloc, així com el seu rol dins del futur de la nanoelectrònica comparat amb altres tecnologies emergents. Després, per tal d’entendre i determinar les interaccions que tenen lloc durant el procés d’auto-assemblatge, es dóna una visió general sobre els processos químics i físics que tenen lloc en les pel·lícules primes de copolímers de bloc. La part principal de la tesi es focalitza en l’estudi, desenvolupament i implementació d’un mètode de guiatge químic per tal de dirigir l’auto-assemblatge de copolímers de bloc. A banda d’estudiar el procés experimental, també es caracteritzen els mecanismes que condueixen l’alineament i s’introdueixen a un model per simular el procés d’auto-assemblatge dirigit. A més, també es presenta la transferència del procés a una línia pilot industrial de fabricació de circuits integrats. La implementació del procés de guiatge químic s’ha provat no únicament amb materials comercials, sinó també amb nous sistemes polimèrics que permeten arribar a mides per sota dels 10 nm. Per aquests sistemes, es defineix un nou mètode de guiatge basat en la combinació de modificacions topogràfiques i químiques. Per tal d’entendre millor el procés, s’estudien tècniques específiques de metrologia. En particular, mitjançant tècniques d’alta energia de rajos X, es descriuen les principals diferències entre patrons químics de guiatge. D’altra banda, les propietats nanomecàniques dels diferents dominis del copolímer es determinen mitjançant el mode peak force tapping de la microscòpia de força atòmica. Finalment, es mostra un mètode per transferir els motius del copolímer al substrat. Aquest es basa en la infiltració d’un domini del copolímer. La infiltració canvia les propietats del material i el fa més resistiu al gravat amb oxigen. D’altra banda, i com a aplicació final, es presenta un procés de fabricació de ressonadors nanomecànics, basats en el procés d’auto-assemblatge de copolímers de bloc amb infiltració.The thesis entitled “Directed self-assembly of block copolymers on chemically nano-patterned surfaces”, aboard the challenge of the development, implementation and characterization of a chemical epitaxy process to direct self-assemble block copolymers. The development of this nanofabrication method contributes to the next generation of nanoelectronic devices and circuits. Firstly, the main aspects of directed self-assembly of block copolymers and its role and status in the future of nanoelectronics is presented, and compared with other powerful technologies. Then, a general overview about the physics and chemistry involved in block copolymer thin films is presented, in order to understand and determine the interactions taking place during the DSA process. The main part of the thesis is focused on the study, development and implementation of a chemical epitaxy approach to guide the self-assembly of block copolymers. Apart from the process development, the mechanisms which drive the block copolymer alignment are characterized and simulated into a DSA model. Moreover, the process transfer to a more industrial pilot line is presented. The implementation of the chemical epitaxy process is addressed not only with commercial block copolymers, but also with new polymer systems which allow getting sub- 10 nm resolution. For these systems, a new guiding method is presented based on the combination of a chemical and graphoepitaxy approach. To better understand the DSA process, dedicated metrology methods are also studied. In particular, by using high-energy X-ray techniques it is possible to describe the main characteristics of the chemical guiding patterns. On the other hand, the nanomechanical properties of block copolymer domains are studied by using the peak force tapping mode in atomic force microscopy. A reliable method to pattern transfer the block copolymer features into the substrate is showed. It is based on infiltrating one block copolymer domain and enhancing thus, its resistivity to plasma etching. Finally, as a final application, a novel fabrication process of a nanowire mechanical resonator by means of DSA and infiltration is presented

Directed self-assembly of block copolymers on chemically nano-patterned surfaces /

Premi Extraordinari de Doctorat concedit pels programes de doctorat de la UAB per curs acadèmic 2016-2017La tesi doctoral titulada "Auto-assemblatge de copolímers de bloc per modificació química de la superfície", presenta com a objectiu principal el desenvolupament, implementació i caracterització d'un mètode de guiatge de copolímers de bloc basat en la modificació química de la superfície. El desenvolupament d'aquest mètode de nanofabricació contribueix a la futura generació de dispositius i circuits nanoelectrònics. Primer de tot, es presenten els aspectes generals sobre l'auto-assemblatge dirigit de copolímers de bloc, així com el seu rol dins del futur de la nanoelectrònica comparat amb altres tecnologies emergents. Després, per tal d'entendre i determinar les interaccions que tenen lloc durant el procés d'auto-assemblatge, es dóna una visió general sobre els processos químics i físics que tenen lloc en les pel·lícules primes de copolímers de bloc. La part principal de la tesi es focalitza en l'estudi, desenvolupament i implementació d'un mètode de guiatge químic per tal de dirigir l'auto-assemblatge de copolímers de bloc. A banda d'estudiar el procés experimental, també es caracteritzen els mecanismes que condueixen l'alineament i s'introdueixen a un model per simular el procés d'auto-assemblatge dirigit. A més, també es presenta la transferència del procés a una línia pilot industrial de fabricació de circuits integrats. La implementació del procés de guiatge químic s'ha provat no únicament amb materials comercials, sinó també amb nous sistemes polimèrics que permeten arribar a mides per sota dels 10 nm. Per aquests sistemes, es defineix un nou mètode de guiatge basat en la combinació de modificacions topogràfiques i químiques. Per tal d'entendre millor el procés, s'estudien tècniques específiques de metrologia. En particular, mitjançant tècniques d'alta energia de rajos X, es descriuen les principals diferències entre patrons químics de guiatge. D'altra banda, les propietats nanomecàniques dels diferents dominis del copolímer es determinen mitjançant el mode peak force tapping de la microscòpia de força atòmica. Finalment, es mostra un mètode per transferir els motius del copolímer al substrat. Aquest es basa en la infiltració d'un domini del copolímer. La infiltració canvia les propietats del material i el fa més resistiu al gravat amb oxigen. D'altra banda, i com a aplicació final, es presenta un procés de fabricació de ressonadors nanomecànics, basats en el procés d'auto-assemblatge de copolímers de bloc amb infiltració.The thesis entitled "Directed self-assembly of block copolymers on chemically nano-patterned surfaces", aboard the challenge of the development, implementation and characterization of a chemical epitaxy process to direct self-assemble block copolymers. The development of this nanofabrication method contributes to the next generation of nanoelectronic devices and circuits. Firstly, the main aspects of directed self-assembly of block copolymers and its role and status in the future of nanoelectronics is presented, and compared with other powerful technologies. Then, a general overview about the physics and chemistry involved in block copolymer thin films is presented, in order to understand and determine the interactions taking place during the DSA process. The main part of the thesis is focused on the study, development and implementation of a chemical epitaxy approach to guide the self-assembly of block copolymers. Apart from the process development, the mechanisms which drive the block copolymer alignment are characterized and simulated into a DSA model. Moreover, the process transfer to a more industrial pilot line is presented. The implementation of the chemical epitaxy process is addressed not only with commercial block copolymers, but also with new polymer systems which allow getting sub- 10 nm resolution. For these systems, a new guiding method is presented based on the combination of a chemical and graphoepitaxy approach. To better understand the DSA process, dedicated metrology methods are also studied. In particular, by using high-energy X-ray techniques it is possible to describe the main characteristics of the chemical guiding patterns. On the other hand, the nanomechanical properties of block copolymer domains are studied by using the peak force tapping mode in atomic force microscopy. A reliable method to pattern transfer the block copolymer features into the substrate is showed. It is based on infiltrating one block copolymer domain and enhancing thus, its resistivity to plasma etching. Finally, as a final application, a novel fabrication process of a nanowire mechanical resonator by means of DSA and infiltration is presented

Determination of the interfacial energies in chemical guiding patterns for directed self-assembly of block co-polymers

Trabajo presentado a la 41st International Conference on Micro and Nano Engineering, celebrada en Hague (Netherlands) del 21 al 24 de septiembre de 2015.Directed self-assembly (DSA) of block co-polymers allows the generation of high-resolution patterns at wafer scale level. The characteristic feature size of the final pattern is dictated by the molecular weight of the block co-polymer, while its orientation is prompted by the pre-definition of guiding patterns on the surface. In chemical epitaxy DSA, the guiding patterns are defined as areas of the surface of varied chemical strength (affinity) with the blocks forming the co-polymer. In this communication, we present a method to experimentally determine the interface energies and a quantitative estimation between surface affinity strength and guidance capability of the chemical patterns. We use PS-b-PMMA as block copolymer and PS-OH as brush layer. Chemical guiding patterns are created by selective exposure of the brush layer to oxygen plasma]. The difference of surface free energy of each segment of the copolymer with the confining boundary (γSA - γSB), is the main driving force in chemical epitaxy DSA. It is experimentally estimated from de-wetting experiments using blends of homopolymers, which are performed under the same conditions than the ones used for DSA of as block copolymers. When thermally annealed, the two immiscible homopolymers exhibit phase separation and the contact angle ΦAB between both polymers (A and B) and the substrate (S) can be obtained (see figure 1). Then, the interfacial energy (Δγ) can be estimated by Youngís equation: Δγ = γSA - γSB = γAB.cos(ΦAB) where γSA and γSB are the interface tension between homopolymers A and B with the substrate, and γSA is the interface tension between both polymers, which depends on the annealing temperature. Figure 2 shows the typical morphology for a blend of PS/PMMA polymers on a pristine PSOH surface (a) and on a PS-OH surface chemically modified by oxygen plasma exposure (b). After selective removal of PMMA, the contact angle is estimated from cross-sectional SEM images. The properties of the formed droplet are further investigated by atomic force microscopy employing Peak ForceTM tapping mode. This technique allows the acquisition of multiple force distance curves with improved force resolution (0.1-10 nN), with real time calculation of mechanical properties at each point. Mechanical properties such as adhesion force and surface stiffness of polymer blends are mapped with nanometric resolution as shown in Figure 3. Two examples of the relevance of the interface energy in chemical epitaxy DSA are shown in figure 4 where the guiding stripes are defined by soft or strong oxygen plasma. A pristine PS-OH layer presents preferential affinity to the PS block. When it is exposed to oxygen plasma, it becomes more attractive to PMMA, being the affinity larger when the plasma is stronger (higher power and longer exposure time). As a result. two completely different morphologies of the DSA patterns are obtained: for the soft plasma case, we obtain vertical lamella oriented in the direction of the guiding stripes while for the strong oxygen plasma exposure, the PS-b-PMMA lamella are placed parallel to the substrate above the guiding stripes and turn vertical with perpendicular orientation above the non-guiding stripes. Quantitative results of the interface energy and a more complete investigation of their relation with the guiding pattern efficiency will be presented at the conference.The research leading to these results received funding from the European Unionís Seventh Framework Programme FP7/2007-2013, under project CoLiSA. L. Evangelio acknowledges MECD for the PhD contract FPU13/03746.Peer Reviewe