than simply decorating the surface. [2][3][4] SIS allows transforming polymers into organic-inorganic hybrid materials: penetration and reaction of gaseous metal precursors into polymer, during SIS, permit to grow inorganic materials into polymeric films [5] in order to tune some of their features as their optical properties or improve their chemical etch resistance. [6][7][8][9] The SIS process is characterized by two factors: diffusion and entrapment of precursor molecules into the polymer matrix. The most direct method to promote their entrapment is the chemical reaction of penetrant molecules with polymer functional groups in combination with a secondary precursor (coreactant). [4] Thus, the number of reactive sites within the polymer film plays an important role in the determination of the amount of inorganic material grown in the film during the process. Moreover, differently from ALD, the self-terminating reactions are not restricted to the surface sites. Precursor molecules must diffuse into the polymeric film to reach the reactive sites that are distributed in the volume of the polymeric matrix. Consequently, diffusion plays a fundamental part in the kinetics of the infiltration process and needs to be monitored in real time. The most used in situ techniques for investigating the infiltration mechanism are in situ quartz crystal microbalance (QCM) measurements and in situ Fourier transform infrared (FTIR) spectroscopy. [10][11][12][13] In situ dynamic spectroscopic ellipsometry (SE) was recently validated as a valuable tool for real time investigation of the infiltration process in poly(methyl methacrylate) (PMMA) and polystyrene (PS) homopolymers. [14] In situ SE is a noninvasive optical technique frequently used in combination with ALD processes [15][16][17] and for studies of polymer films under several conditions. [18][19][20] During SIS process, in situ SE allows continuous acquisition of information about changes of thickness and refractive index (n) of polymer films without interrupting the process itself on a shorter time scale than in situ FTIR spectroscopic analysis and without the need of ad hoc samples as for QCM measurements. When SIS is performed into self-assembled block copolymers (BCP), [21] the selective binding of precursors to one domain only of BCPs offers the possibility to fabricate inorganic functional nanoarchitectures [22] or hard masks for lithography. [23] Removing polymers by O 2 plasma after Sequential infiltration synthesis (SIS) consists in a controlled sequence of metal organic precursors and coreactant vapor exposure cycles of polymer films. Two aspects characterize an SIS process: precursor molecule diffusion within the polymer matrix and precursor molecule entrapment into polymer films via chemical reaction. In this paper, SIS process for the alumina synthesis is investigated using trimethylaluminum (TMA) and H 2 O in thin films of poly(styrene-random-methyl methacrylate) (P(S-r-MMA)) with variable MMA content. The amount of alumina grown in the P(S-r-MMA) films linear...

Polystyrene samples with different molar mass and narrow polydispersity index were prepared by nitroxide-mediated polymerization using N-tert-butyl-N-[1-diethyl­phosphono­(2,2-dimethylpropyl)] nitroxide (SG1) as a radical controller and phosphorus containing moiety, and their doping performances were studied. In contrast to what is observed for conventional “grafting to” reactions, the thickness of the grafted layer is observed to rapidly increase with time, reaching a thickness plateau value that is significantly lower than 2 times the radius of gyration of the corresponding polymer chain. In addition, the plateau thickness initially increases as the molar mass of the grafting polymer increases and then reaches a somewhat limiting thickness. Interestingly, the phosphorus areal dose on the silicon surface is equal to the density of the grafted chains estimated from the thickness of the brush layer. The overall data indicate that during the high-temperature thermal treatment two parallel and competing reactions are operating, namely, the “grafting to” reaction and a degradation of the SG1 moiety that leads to fragments, as confirmed by direct exposure probe analysis. This combination results in a fine-tuning of the phosphorus dose at the substrate surface with a substantial outperforming of the dopant dose control, achieved by using conventional self-assembled monolayers.

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.