Michele Perego - Academia.edu (original) (raw)
Papers by Michele Perego
Polymer International, Jan 13, 2022
Materials Science in Semiconductor Processing, Oct 1, 2023
Nanotechnology, Sep 25, 2015
Binary homopolymer blends of two hydroxyl-terminated polystyrene (PS-OH) and polymethylmethacryla... more Binary homopolymer blends of two hydroxyl-terminated polystyrene (PS-OH) and polymethylmethacrylate (PMMA-OH) homopolymers (Mn ∼ 16000 g mol(-1)) were grafted on SiO2 substrates by high-temperature (T > 150 °C), short-time (t < 600 s) thermal treatments. The resulting brush layer was tested to screen preferential interactions of the SiO2 substrate with the different symmetric and asymmetric PS-b-PMMA block copolymers deposited on top of the grafted molecules. By properly adjusting the blend composition and the processing parameters, an efficient surface neutralization path was identified, enabling the formation, in the block copolymer film, of homogeneous textures of lamellae or cylinders perpendicularly oriented with respect to the substrate. A critical interplay between the phase segregation of the homopolymer blends and their grafting process on the SiO2 was observed. In fact, the polar SiO2 is preferential for the PMMA-rich phase that forms a homogeneous layer on the substrate, while the PS-rich phase is located at the polymer-air interface. During the thermal treatment, phase segregation and grafting proceed simultaneously. Complete wetting of the PS rich phase on the PMMA rich phase leads to the formation of a PS/PMMA bilayer. In this case, the progressive diffusion of PS chains toward the polymer-SiO2 interface during the thermal treatment allows tuning of the brush layer composition.
Surface and Interface Analysis, Jun 12, 2014
Nanotechnology, Oct 20, 2020
IEEE International Reliability Physics Symposium proceedings, Apr 1, 2009
A systematic study of mobility performances and Bias Temperature Instability (BTI) reliability wa... more A systematic study of mobility performances and Bias Temperature Instability (BTI) reliability was done on a large variety of advanced dielectric stacks. We clearly demonstrate that mobility performances and NBTI reliability are strongly correlated and that they are affected by the diffusion of nitrogen species N at the Si interface. Reducing the metal gate thickness favors the reduction of mobility degradations and NBTI, but, also strongly enhances PBTI, due to a complex set of reactions in the gate oxide. An optimum gate thickness must be found to obtain an acceptable trade off between device performance and reliability requirements.
HAL (Le Centre pour la Communication Scientifique Directe), Oct 1, 2016
ACS Applied Materials & Interfaces, Jun 14, 2023
Physica Status Solidi A-applications and Materials Science, Mar 1, 2018
Springer eBooks, Nov 7, 2006
The critical role of gate oxide in ultra-scaled devices is being investigated in terms of the pro... more The critical role of gate oxide in ultra-scaled devices is being investigated in terms of the properties of rare earth oxides as high dielectric constant (high-κ) materials to replace SiO2. In particular, the combination of rare earth oxides with high-mobility substrates, like Ge and GaAs, could offer the possibility to improve the interface properties. Among the different properties under investigation,
Nucleation and Atmospheric Aerosols, 2018
A fully calibrated and validated TGA-GC–MS is proposed for the quantitative analysis of diethylph... more A fully calibrated and validated TGA-GC–MS is proposed for the quantitative analysis of diethylphosphate- end capped polymers. It allows the determination of the amount of phosphorous in polymeric samples and also thedetermination of the number of repeating units per chain end. Since no sample pretreatments are required polymeric films supported on inert substrates can be directly analyzed even in ultrathinfilms with thickness of few tens of nanometers. Finally, the chromatographic profile of the species evolving during the thermal degradation depend on the polymeric film thickness allowing that information concerning the polymer stability anddegradation mechanism at different size scale can be obtained. Considering the widespread interest for thin and ultrathin films of polymers containing phosphorous groupsfor brush-based technologies, the proposed method can be helpful in various areas, including flame retardantmaterial, healthcare and medicine, microelectronic, for facile and precise characterization ...
Nucleation and Atmospheric Aerosols, 2018
Boron-terminated polystyrene with molecular weight ranging from 1800 to 18000 g/mol were synthesi... more Boron-terminated polystyrene with molecular weight ranging from 1800 to 18000 g/mol were synthesized for p-type doping of silicon substrates through spin-on technique. Several polymers were prepared using the ARGET-ATRP method using tert-butyl 2-bromoisobutyrate as initiator, changing monomer to initiator ratio and the reaction time. After polymerization, polystyrene samples were functionalized in order to end-cap the chains with a boron-containing molecule. Various polymers were characterized by SEC, to estimate Mn, Mw and PDI, by NMR (1H and 13C) in order to investigate the correct structure of the molecules and by TGA-GC-MS for knowing the thermal behavior and the amount of boron into the polymers.
Polymer Chemistry, 2022
A preferential grafting of short chains occurs during the “grafting to” reaction of hydroxy termi... more A preferential grafting of short chains occurs during the “grafting to” reaction of hydroxy terminated P(S-st-MMA) blends consisting of short and long chains. The enrichment is enhanced when the chain length difference increases.
Journal of Applied Physics, Feb 14, 2022
Nanotechnology, Jan 20, 2016
Achieving the required control of dopant distribution and selectivity for nanostructured semicond... more Achieving the required control of dopant distribution and selectivity for nanostructured semiconducting building block is a key issue for a large variety of applications. A promising strategy is monolayer doping (MLD), which consists in the creation of a well-ordered monolayer of dopant-containing molecules bonded to the surface of the substrate. In this work, we synthesize a P δ-layer embedded in a SiO2 matrix by MLD. Using a multi-technique approach based on time of flight secondary ion mass spectrometry (ToF-SIMS) and Rutherford backscattering spectrometry (RBS) analyses, we characterize the tuning of P dose as a function of the processing time and temperature. We found the proper conditions for a full grafting of the molecules, reaching a maximal dose of 8.3 × 10(14) atoms/cm(2). Moreover, using 1D rate equation model, we model P diffusion in SiO2 after annealing and we extract a P diffusivity in SiO2 of 1.5 × 10(17) cm(2) s(-1).
Defect and Diffusion Forum, Oct 1, 2006
Macromolecules, Dec 14, 2020
Nanotechnology, May 7, 2015
Block copolymer-based templates can be exploited for the fabrication of ordered arrays of metal n... more Block copolymer-based templates can be exploited for the fabrication of ordered arrays of metal nanoparticles (NPs) with a diameter down to a few nanometers. In order to develop this technique on metal oxide substrates, we studied the self-assembly of polymeric templates directly on the HfO₂ surface. Using a random copolymer neutralization layer, we obtained an effective HfO₂ surface neutralization, while the effects of surface cleaning and annealing temperature were carefully examined. Varying the block copolymer molecular weight, we produced regular nanoporous templates with feature size variable between 10 and 30 nm and a density up to 1.5 × 10¹¹ cm⁻². With the adoption of a pattern transfer process, we produced ordered arrays of Pt and Pt/Ti NPs with diameters of 12, 21 and 29 nm and a constant size dispersion (σ) of 2.5 nm. For the smallest template adopted, the NP diameter is significantly lower than the original template dimension. In this specific configuration, the granularity of the deposited film probably influences the pattern transfer process and very small NPs of 12 nm were achieved without a significant broadening of the size distribution.
Polymer International, Jan 13, 2022
Materials Science in Semiconductor Processing, Oct 1, 2023
Nanotechnology, Sep 25, 2015
Binary homopolymer blends of two hydroxyl-terminated polystyrene (PS-OH) and polymethylmethacryla... more Binary homopolymer blends of two hydroxyl-terminated polystyrene (PS-OH) and polymethylmethacrylate (PMMA-OH) homopolymers (Mn ∼ 16000 g mol(-1)) were grafted on SiO2 substrates by high-temperature (T > 150 °C), short-time (t < 600 s) thermal treatments. The resulting brush layer was tested to screen preferential interactions of the SiO2 substrate with the different symmetric and asymmetric PS-b-PMMA block copolymers deposited on top of the grafted molecules. By properly adjusting the blend composition and the processing parameters, an efficient surface neutralization path was identified, enabling the formation, in the block copolymer film, of homogeneous textures of lamellae or cylinders perpendicularly oriented with respect to the substrate. A critical interplay between the phase segregation of the homopolymer blends and their grafting process on the SiO2 was observed. In fact, the polar SiO2 is preferential for the PMMA-rich phase that forms a homogeneous layer on the substrate, while the PS-rich phase is located at the polymer-air interface. During the thermal treatment, phase segregation and grafting proceed simultaneously. Complete wetting of the PS rich phase on the PMMA rich phase leads to the formation of a PS/PMMA bilayer. In this case, the progressive diffusion of PS chains toward the polymer-SiO2 interface during the thermal treatment allows tuning of the brush layer composition.
Surface and Interface Analysis, Jun 12, 2014
Nanotechnology, Oct 20, 2020
IEEE International Reliability Physics Symposium proceedings, Apr 1, 2009
A systematic study of mobility performances and Bias Temperature Instability (BTI) reliability wa... more A systematic study of mobility performances and Bias Temperature Instability (BTI) reliability was done on a large variety of advanced dielectric stacks. We clearly demonstrate that mobility performances and NBTI reliability are strongly correlated and that they are affected by the diffusion of nitrogen species N at the Si interface. Reducing the metal gate thickness favors the reduction of mobility degradations and NBTI, but, also strongly enhances PBTI, due to a complex set of reactions in the gate oxide. An optimum gate thickness must be found to obtain an acceptable trade off between device performance and reliability requirements.
HAL (Le Centre pour la Communication Scientifique Directe), Oct 1, 2016
ACS Applied Materials & Interfaces, Jun 14, 2023
Physica Status Solidi A-applications and Materials Science, Mar 1, 2018
Springer eBooks, Nov 7, 2006
The critical role of gate oxide in ultra-scaled devices is being investigated in terms of the pro... more The critical role of gate oxide in ultra-scaled devices is being investigated in terms of the properties of rare earth oxides as high dielectric constant (high-κ) materials to replace SiO2. In particular, the combination of rare earth oxides with high-mobility substrates, like Ge and GaAs, could offer the possibility to improve the interface properties. Among the different properties under investigation,
Nucleation and Atmospheric Aerosols, 2018
A fully calibrated and validated TGA-GC–MS is proposed for the quantitative analysis of diethylph... more A fully calibrated and validated TGA-GC–MS is proposed for the quantitative analysis of diethylphosphate- end capped polymers. It allows the determination of the amount of phosphorous in polymeric samples and also thedetermination of the number of repeating units per chain end. Since no sample pretreatments are required polymeric films supported on inert substrates can be directly analyzed even in ultrathinfilms with thickness of few tens of nanometers. Finally, the chromatographic profile of the species evolving during the thermal degradation depend on the polymeric film thickness allowing that information concerning the polymer stability anddegradation mechanism at different size scale can be obtained. Considering the widespread interest for thin and ultrathin films of polymers containing phosphorous groupsfor brush-based technologies, the proposed method can be helpful in various areas, including flame retardantmaterial, healthcare and medicine, microelectronic, for facile and precise characterization ...
Nucleation and Atmospheric Aerosols, 2018
Boron-terminated polystyrene with molecular weight ranging from 1800 to 18000 g/mol were synthesi... more Boron-terminated polystyrene with molecular weight ranging from 1800 to 18000 g/mol were synthesized for p-type doping of silicon substrates through spin-on technique. Several polymers were prepared using the ARGET-ATRP method using tert-butyl 2-bromoisobutyrate as initiator, changing monomer to initiator ratio and the reaction time. After polymerization, polystyrene samples were functionalized in order to end-cap the chains with a boron-containing molecule. Various polymers were characterized by SEC, to estimate Mn, Mw and PDI, by NMR (1H and 13C) in order to investigate the correct structure of the molecules and by TGA-GC-MS for knowing the thermal behavior and the amount of boron into the polymers.
Polymer Chemistry, 2022
A preferential grafting of short chains occurs during the “grafting to” reaction of hydroxy termi... more A preferential grafting of short chains occurs during the “grafting to” reaction of hydroxy terminated P(S-st-MMA) blends consisting of short and long chains. The enrichment is enhanced when the chain length difference increases.
Journal of Applied Physics, Feb 14, 2022
Nanotechnology, Jan 20, 2016
Achieving the required control of dopant distribution and selectivity for nanostructured semicond... more Achieving the required control of dopant distribution and selectivity for nanostructured semiconducting building block is a key issue for a large variety of applications. A promising strategy is monolayer doping (MLD), which consists in the creation of a well-ordered monolayer of dopant-containing molecules bonded to the surface of the substrate. In this work, we synthesize a P δ-layer embedded in a SiO2 matrix by MLD. Using a multi-technique approach based on time of flight secondary ion mass spectrometry (ToF-SIMS) and Rutherford backscattering spectrometry (RBS) analyses, we characterize the tuning of P dose as a function of the processing time and temperature. We found the proper conditions for a full grafting of the molecules, reaching a maximal dose of 8.3 × 10(14) atoms/cm(2). Moreover, using 1D rate equation model, we model P diffusion in SiO2 after annealing and we extract a P diffusivity in SiO2 of 1.5 × 10(17) cm(2) s(-1).
Defect and Diffusion Forum, Oct 1, 2006
Macromolecules, Dec 14, 2020
Nanotechnology, May 7, 2015
Block copolymer-based templates can be exploited for the fabrication of ordered arrays of metal n... more Block copolymer-based templates can be exploited for the fabrication of ordered arrays of metal nanoparticles (NPs) with a diameter down to a few nanometers. In order to develop this technique on metal oxide substrates, we studied the self-assembly of polymeric templates directly on the HfO₂ surface. Using a random copolymer neutralization layer, we obtained an effective HfO₂ surface neutralization, while the effects of surface cleaning and annealing temperature were carefully examined. Varying the block copolymer molecular weight, we produced regular nanoporous templates with feature size variable between 10 and 30 nm and a density up to 1.5 × 10¹¹ cm⁻². With the adoption of a pattern transfer process, we produced ordered arrays of Pt and Pt/Ti NPs with diameters of 12, 21 and 29 nm and a constant size dispersion (σ) of 2.5 nm. For the smallest template adopted, the NP diameter is significantly lower than the original template dimension. In this specific configuration, the granularity of the deposited film probably influences the pattern transfer process and very small NPs of 12 nm were achieved without a significant broadening of the size distribution.