arXiv subjects

Fulvio Mazzamuto

Publications and source records attributed to Fulvio Mazzamuto.

8 recordsLinked to original sources

arXiv2025

Impact of impurities on leakage current induced by High-Energy Density Pulsed Laser Annealing in Si diodes

For semiconductor device fabrication, Pulsed Laser Annealing (PLA) offers significant advantages over conventional thermal processes. Notably, it can provide ultrafast (~ns) and high temperature profiles ($>1000^\circ$C). When the maximum temperature exceeds the melting point, a solid-liquid phase transition is observed, immediately followed by rapid recrystallization. This unique annealing mechanism gives raises questions about dopant diffusion and residual defects, in not only in the recrystallized region, but also just below it. As power devices require micrometer-sized junctions, high laser energy densities are needed, which were proved to promote the incorporation of complex impurities from the surface and the creation of defects at the liquid/solid interface. This paper reports on the impact of laser annealing at high energy densities (up to 8.0 J/cm$^2$) on the leakage current, using Schottky and PN diodes, and DLTS measurements. Various laser annealing conditions were used: energy densities between 1.7 and 8.0 J/cm$^2$ with 1 to 10 pulses. Our results suggest that the liquid and solid solubility of vacancies in silicon are fixed by the maximum temperature reached, so to the energy density. Increasing the number of laser pulses allows, not only to reach this maximum vacancy concentration but also to promote their diffusion towards the surface. Concomitantly, the in-diffusion of complex impurities inside the melted region allows the coupling between both defect types to create trap centers, responsible for the degradation of the leakage current.

cond-mat.mtrl-sci↗

arXiv2022

Microsecond non-melt UV laser annealing for future 3D-stacked CMOS

Three-dimensional (3D) CMOS technology encourages the use of UV laser annealing (UV-LA) because the shallow absorption of UV light into materials and the process timescale typically from nanoseconds (ns) to microseconds (us) strongly limit the vertical heat diffusion. In this work, us UV-LA solid phase epitaxial regrowth (SPER) demonstrated an active carrier concentration surpassing 1 x 10^21 at./cm^-3 in an arsenic ion-implanted silicon-on-insulator substrate. After the subsequent ns UV-LA known for improving CMOS interconnect, only a slight (about 5%) sheet resistance increase was observed. The results open a possibility to integrate UV-LA at different stages of 3D-stacked CMOS.

physics.app-ph↗

arXiv2022

Solid Phase Recrystallization in Arsenic Ion-Implanted Silicon-On-Insulator by Microsecond UV Laser Annealing

UV laser annealing (UV-LA) enables surface-localized high-temperature thermal processing to form abrupt junctions in emerging monolithically stacked devices, where the applicable thermal budget is restricted. In this work, UV-LA is performed to regrow a silicon-on-insulator wafer partially amorphized by arsenic ion implantation as well as to activate the dopants. In a microsecond scale ( 10^-6 s to 10^-5 s) UV-LA process, monocrystalline solid phase recrystallization and dopant activation without junction deepening are evidenced, thus opening various applications in low thermal budget integration flows. However, some concerns remain. First, the surface morphology is degraded after the regrowth, possibly because of the non-perfect uniformity of the used laser beam and/or the formation of defects near the surface involving the excess dopants. Second, many of the dopants are inactive and seem to form deep levels in the Si band gap, suggesting a further optimization of the ion implantation condition to manage the initial crystal damage and the heating profile to better accommodate the dopants into the substitutional sites.

physics.app-ph↗

arXiv2022

Failure Mode Analysis in Microsecond UV Laser Annealing of Cu Thin Films

The need of surface-localized thermal processing is strongly increasing especially w.r.t three-dimensionally (3D) integrated electrical devices. UV laser annealing (UV-LA) technology well addresses this challenge. Particularly UV-LA can reduce resistivity by enlarging metallic grains in lines or thin films, irradiating only the interconnects for short timescales. However, the risk of failure in electrical performance must be correctly managed, and that of UV-LA has not been deeply studied yet. In this work microsecond-scale UV-LA is applied on a stack comparable to an interconnect structure (dielectric/Cu/Ta/SiO2/Si) in either melt or sub-melt regime for grain growth. The failure modes such as (i) Cu diffusion into SiO2, (ii) O incorporation into Cu, and (iii) intermixing between Cu and Ta are investigated.

physics.app-ph↗

arXiv2021

Solid Phase Recrystallization and Dopant Activation in Arsenic Ion-Implanted Silicon-On-Insulator by UV Laser Annealing

UV laser annealing (UV-LA) enables surface-localized high-temperature thermal processing to form abrupt junctions in emerging monolithically stacked devices, where applicable thermal budget is restricted. In this work, UV-LA is performed to regrow a SOI layer partially amorphized by arsenic ion implantation and to activate the dopants. In a microsecond scale (~10^-6 s to ~10^-5 s) UV-LA process, monocrystalline solid phase recrystallization and dopant activation without junction deepening is evidenced, thus opening various applications in low thermal budget integration flows.

physics.app-ph↗

arXiv2021

Copper Large-scale Grain Growth by UV Nanosecond Pulsed Laser Annealing

UV nanosecond pulsed laser annealing (UV NLA) enables both surface-localized heating and short timescale high temperature processing, which can be advantageous to reduce metal line resistance by enlarging metal grains in lines or in thin films, while maintaining the integrity and performance of surrounding structures. In this work UV NLA is applied on a typical Cu thin film, demonstrating a mean grain size of over 1 μm and 400 nm in a melt and sub-melt regime, respectively. Along with such grain enlargement, film resistivity is also reduced.

physics.app-ph↗

arXiv2021

Dopant redistribution and activation in Ga ion-implanted high Ge content SiGe by explosive crystallization during UV nanosecond pulsed laser annealing

Explosive crystallization (EC) is often observed when using nanosecond-pulsed melt laser annealing (MLA) in amorphous silicon (Si) and germanium (Ge). The solidification velocity in EC is so fast that a diffusion-less crystallization can be expected. In the contacts of advanced transistors, the active level at the metal/semiconductor Schottky interface must be very high to achieve a sub-10^{-9} ohm.cm2 contact resistivity, which has been already demonstrated by using the dopant surface segregation induced by MLA. However, the beneficial layer of a few nanometers at the surface may be easily consumed during subsequent contact cleaning and metallization. EC helps to address such kind of process integration issues, enabling the optimal positioning of the peak of the dopant chemical profile. However, there is a lack of experimental studies of EC in heavily-doped semiconductor materials. Furthermore, to the best of our knowledge, dopant activation by EC has never been experimentally reported. In this paper, we present dopant redistribution and activation by an EC process induced by UV nanosecond-pulsed MLA in heavily gallium (Ga) ion-implanted high Ge content SiGe. Based on the obtained results, we also highlight potential issues of integrating EC into real device fabrication processes and discuss how to manage them.

cond-mat.mtrl-sci↗

arXiv2012

Resonant tunneling diode based on graphene/h-BN heterostructure

In this letter, we propose the resonant tunneling diode (RTD) based on a double-barrier graphene/boron nitride (BN) heterostructure as device suitable to take advantage of the elaboration of atomic sheets containing different domains of BN and C phases within a hexagonal lattice. The device operation and performance are investigated by means of a self- consistent model within the non-equilibrium Green's function formalism on a tight-binding Hamiltonian. This RTD exhibits a negative differential conductance effect which involves the resonant tunneling through both the electron and hole bound states of the graphene quantum well. It is shown that the peak- to-valley ratio can reach the value of 4 at room temperature for gapless graphene and the value of 13 for a bandgap of 50 meV.

cond-mat.mes-hall↗