Papers by Author: Giuseppe Abbondanza

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Authors: Giuseppe D'Arrigo, Andrea Severino, G. Milazzo, Corrado Bongiorno, Nicolò Piluso, Giuseppe Abbondanza, Marco Mauceri, Giuseppe Condorelli, Francesco La Via
Abstract: 3C-SiC devices are hampered by the defect density in heteroepitaxial films. Acting on the substrate, it is possible to achieve a better compliance between Si and 3C-SiC. We present here an approach to favorite defect geometrical reduction in both [ ] and [ ] directions by creating Inverted Silicon Pyramids (ISP). A study of 3C-SiC growth on ISP is reported showing benefits in the film quality and a reduction in the linear density of stacking faults. Growth on ISP leads also to a decrease in the 3C-SiC residual stress as well as in the bow of the Si/SiC system.
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Authors: Ruggero Anzalone, Andrea Severino, Giuseppe D'Arrigo, Corrado Bongiorno, Patrick Fiorenza, Gaetano Foti, Giuseppe Condorelli, Marco Mauceri, Giuseppe Abbondanza, Francesco La Via
Abstract: The aim of this work is to improve the heteroepitaxial growth process of 3C-SiC on Si substrates using Trichlorosilane (SiHCl3) as the silicon growth precursor. With this precursor it has been shown that it is possible to simultaneously increase the growth rate of the process and avoid the nucleation of silicon droplets in the gas phase. Growth experiments were conducted on three (3) Si substrate orientations in order to assess the impact of the Si substrate on the resulting 3C-SiC film. X-ray Diffraction (XRD), Atomic Force Microscopy (AFM) and Transmission Electron Microscopy (TEM) analysis show the important role of the substrate orientation for the growth process. The different orientation of the substrate modifies the morphology of the 3C-SiC crystalline structure, mostly by changing the density of micro-twins and stacking faults inside the film.
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Authors: Andrea Severino, Massimo Camarda, Nicolò Piluso, M. Italia, Giuseppe Condorelli, Marco Mauceri, Giuseppe Abbondanza, Francesco La Via
Abstract: Growth of 3C-SiC films on an off-axis (111) Si substrate, with a miscut of 4° towards the <110> direction, is here reported. An extensive material characterization has been conducted by means of Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD) and Raman spectroscopy, indicating a very promising film quality with extremely flat surface and interface. Notwithstanding the excellent film quality, the wafer bow is still limiting its full employment in device realization.
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Authors: Andrea Severino, Corrado Bongiorno, Stefano Leone, Marco Mauceri, Giuseppe Pistone, Giuseppe Condorelli, Giuseppe Abbondanza, F. Portuese, Gaetano Foti, Francesco La Via
Abstract: 3C-SiC/Si heteroepitaxy is hampered by large mismatches in lattice parameters (19.7%) and thermal expansion coefficient (8%) leading to 3C-SiC films containing high defects density. To reduce the presence of defects, a multi-step growth process in a CVD reactor is used. The aim of the work is to study the effect of carbonization on differently oriented Si surfaces, experiencing a 200°C-wide temperature range in a CVD reactor, to improve the crystalline quality. TEM analysis are carried out to evaluate thickness, crystal orientations and defects of carbonized layers with respect to the time-dependence of the process and to the different orientations of the Si substrate. It will be shown that process-related defects are strictly correlated to the substrate orientation either for size, density, occupied area, shape or thickness. Uniform, flat and crystalline thin SiC films are obtained with a low defect density.
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Authors: Francesco La Via, Fabrizio Roccaforte, Salvatore Di Franco, Alfonso Ruggiero, L. Neri, Ricardo Reitano, Lucia Calcagno, Gaetano Foti, Marco Mauceri, Stefano Leone, Giuseppe Pistone, Giuseppe Abbondanza, Gian Luca Valente, Danilo Crippa
Abstract: The effects of the Si/H2 ratio on the growth of the epitaxial layer and on the epitaxial defects was studied in detail. A large increase of the growth rate has been observed with the increase of the silicon flux in the CVD reactor. Close to a Si/H2 ratio of 0.05 % silicon nucleation in the gas phase occurs producing a great amount of silicon particles that precipitate on the wafers. The epitaxial layers grown with a Si/H2 ratio of 0.03% show a low defect density and a low leakage current of the Schottky diodes realized on these wafers. For these diodes the DLTS spectra show thepresence of several peaks at 0.14, 0.75, 1.36 and 1.43 eV. For epitaxial layers grown with higher values of the Si/H2 ratio and then with an higher growth rate, the leakage current of the Schottky diodes increases considerably.
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Authors: Alessandro Veneroni, Fabrizio Omarini, Maurizio Masi, Stefano Leone, Marco Mauceri, Giuseppe Pistone, Giuseppe Abbondanza
Abstract: The present production processes for epitaxial SiC do not allow the matching of productivity with the material quality requested by the microelectronics market. Here, to respond to such a demand, a combined experimental and multi-scale – multi-hierarchy modeling approach was adopted. Models allow to verify a priori the role of process operative parameters on the performance ones for both the final product and of the process itself, like growth rate uniformity, film stoichiometry and dopants incorporation, homogeneous nucleation of particulate, microdefects and film morphology. Specifically, in this work the developing of a lumped deposition mechanism is addressed
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Authors: Francesco La Via, G. Galvagno, A. Firrincieli, Fabrizio Roccaforte, Salvatore Di Franco, Alfonso Ruggiero, Milo Barbera, Ricardo Reitano, Paolo Musumeci, Lucia Calcagno, Gaetano Foti, Marco Mauceri, Stefano Leone, Giuseppe Pistone, F. Portuese, Giuseppe Abbondanza, Giovanni Abagnale, Gian Luca Valente, Danilo Crippa
Abstract: The growth rate of 4H-SiC epi layers has been increased by a factor 3 (up to 18μm/h) with respect to the standard process with the introduction of HCl in the deposition chamber. The epitaxial layers grown with the addition of HCl have been characterized by electrical, optical and structural characterization methods. An optimized process without the addition of HCl is reported for comparison. The Schottky diodes, manufactured on the epitaxial layer grown with the addition of HCl at 1600 °C, have electrical characteristics comparable with the standard epitaxial process with the advantage of an epitaxial growth rate three times higher.
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Authors: Maurizio Masi, Alessandro Veneroni, A. Fiorucci, Francesco La Via, Gaetano Foti, Marco Mauceri, Stefano Leone, Giuseppe Pistone, Giuseppe Condorelli, Giuseppe Abbondanza, Gian Luca Valente, Danilo Crippa
Abstract: A simplified deposition model, involving both the description of the deposition and of the film morphology was adopted to quantitatively understand the experimental trends encountered in the epitaxial silicon carbide deposition in an industrial hot wall reactor. The attention was focused on the system involving chlorinated species because its really superior performances with respect the traditional silane/hydrocarbons process. The evolution of the crystalline structure (i.e., from poly to single) and of the surface roughness can be understood by simply comparing two characteristic times, like those inherent the surface diffusion and the matter supply to the surface.
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Authors: Fabrizio Roccaforte, Ferdinando Iucolano, Filippo Giannazzo, Giuseppe Moschetti, Corrado Bongiorno, Salvatore Di Franco, Valeria Puglisi, Giuseppe Abbondanza, Vito Raineri
Abstract: Gallium nitride (GaN) and related alloys (AlxGa1-xN) are promising semiconductors for high-frequency and high-power devices applications. In particular, the growth of AlGaN/GaN heterostructures on SiC substrates, due to the high thermal conductivity of SiC, can lead to significant improvement in the device performances. An important issue in the fabrication of AlGaN/GaN devices is the influence of the required thermal budget (700-900°C) on the properties of Ohmic contacts and device isolation. In this work, the influence of thermal annealing on the fabrication of AlGaN/GaN devices was studied. Ti/Al/Ni/Au multilayers led to an Ohmic behavior with a specific resistance c in the 10-5 cm2 range upon annealing between 750°C and 850°C. The electrical behavior of Ohmic contacts was correlated with the evolution of the formed phases and with the temperature behavior of c. The stability of the inter-device isolation obtained by nitrogen-implantation during annealing at these temperatures was also monitored.
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Authors: Danilo Crippa, Gian Luca Valente, Alfonso Ruggiero, L. Neri, Ricardo Reitano, Lucia Calcagno, Gaetano Foti, Marco Mauceri, Stefano Leone, Giuseppe Pistone, Giuseppe Abbondanza, G. Abbagnale, Alessandro Veneroni, Fabrizio Omarini, L. Zamolo, Maurizio Masi, Fabrizio Roccaforte, G. Giannazzo, Salvatore Di Franco, Francesco La Via
Abstract: The results of a new epitaxial process using an industrial 6x2” wafer reactor with the introduction of HCl during the growth have been reported. A complete reduction of silicon nucleation in the gas phase has been observed even for high silicon dilution parameters (Si/H2>0.05) and an increase of the growth rate until about 20 µm/h has been measured. No difference has been observed in terms of defects, doping uniformity (average maximum variation 8%) and thickness uniformity (average maximum variation 1.2 %) with respect to the standard process without HCl.
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