Structural characterization of in‐situ silicided contacts textured on p‐type [001] silicon

Badalà, Paolo; Faro, Giuseppe; Marcellino, Cinzia M.; Pellegrino, Giovanna; Santangelo, A.; Alberti, Alessandra

doi:10.1002/pssc.201300132

Cited by 5 publications

(3 citation statements)

References 8 publications

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“…A solution to form backside ohmic contacts after front side device definition is therefore required. Among the alternative processes to RTA proposed for Si [5][6][7][8], laser annealing is the most promising one for ohmic contact formation on 4H-SiC [9][10][11][12][13][14][15]. Excimer UV laser annealing has been widely studied for Ni-based ohmic contacts [16], with particular focus on single pulse process, with the aim to understand the early stages of reaction process [17][18].…”

Section: Introductionmentioning

confidence: 99%

Ni-Silicide Ohmic Contacts on 4H-SiC Formed by Multi Pulse Excimer Laser Annealing

Badalà,

Deretzis,

Sanzaro

et al. 2023

SSP

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The formation of ohmic contacts by laser annealing approach is of great importance for SiC power devices, since it allows their fabrication on thin substrates, that is of crucial significance to reduce power dissipation. Ni silicide reaction under UV laser irradiation has been studied in detail with particular focus on single pulse approach, in order to describe the early stage of reaction process. The use of a multi pulse approach, for the formation of Ni silicide-based ohmic contacts by means of excimer laser annealing, has been investigated in this work. The reaction process has been characterized, as a function of number of pulses, by means of X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) analysis. Laser process simulations, formulated in the framework of phase field theory, have been performed in order to predict the evolution of material during reaction under annealing. Simulations show that reaction moves to Si-reach phases with the increasing on pulses, with a co-existence of Ni2Si and Ni3Si2 phases for the three pulses process. Moreover, simulations show critical differences, in terms of the uniformity of the distribution of the silicide phases along the film, between the single pulse and the multi pulses cases and the increasing of thickness of silicide phases with the pulse sequence. These predictions are in good agreement with the findings of XRD and TEM analyses. The electrical properties of the reacted layer have been evaluated on Schottky Barrier Diodes (SBD) devices, confirming the ohmic behaviour of multi pulse annealed samples.

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Section: Introductionmentioning

confidence: 99%

Ni-Silicide Ohmic Contacts on 4H-SiC Formed by Multi Pulse Excimer Laser Annealing

Badalà,

Deretzis,

Sanzaro

et al. 2023

SSP

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“…For power electronics, wafer thinning is assuming a crucial role in ON-Resistance (RON) reduction, but it is demanding at the same time for a new manufacturing approach able to skip the Rapid Thermal Annealing (RTA) process [3]. Among the alternative processes to RTA already demonstrated for Si [4][5][6][7], laser annealing seems to be the most promising for ohmic contact formation on SiC [8]. In particular, the use of UV excimer laser annealing for Nickel-based ohmic contact formation on SiC has been widely studied and reported in literature [9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Structural and Electrical Characterization of Ni-Based Ohmic Contacts on 4H-SiC Formed by Solid-State Laser Annealing

Badalà

Smecca

Rascunà

et al. 2022

MSF

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Laser annealing process for ohmic contact formation on 4H-SiC has attracted increasing attention in the last years, because it enables the fabrication of SiC power devices on very thin substrates. We have investigated the formation of Nickel-based ohmic contact on 4H-SiC by using a Yb:YAG laser in scanning mode, with a wavelength of 515 nm and a pulse duration of 1200 ns. A 100 nm thick Ni layer has been deposited on SiC and irradiated at different process conditions. The reaction process has been studied, as a function of fluence and scan number of laser annealing, by means of X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) analyses. The electrical properties of the annealed layers have been evaluated on Schottky Barrier Diodes (SBDs) devices, confirming the ohmic behavior of the reacted contact and showing improved performances respect to RTA approach. The compatibility of thermal budget of the process in the front side has been verified by means process simulation. A strong relationship between structural properties of reacted layers and electrical behavior of SBDs devices has been revealed. Solid-state laser annealing process, with wavelength in green light region, can indeed represent a suitable solution for ohmic contact formation of 4H-SiC power devices, fabricated on thin substrates.

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“…Knowledge gained in Si-based technologies has been moved to corresponding SiC-based devices and indeed nickel is widely applied in metallization schemes [7,8]. A valid method to induce the formation of Ni-based ohmic contact on 4H-SiC is laser annealing (LA), a viable alternative to Rapid Thermal Annealing (RTA) that has been already extensively used for consolidated Si-based technologies [9,10,11,12,13,14]. In particular, the pulsed UV-lasers typology, offering a suitable penetration depth and the consequent localized annealing at the Ni-side, are applicable for this scope.…”

Section: Introductionmentioning

confidence: 99%

Inter-diffusion, melting and reaction interplay in Ni/4H-SiC under excimer laser annealing

Sanzaro

Bongiorno

Badalà

et al. 2021

Applied Surface Science

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We investigated the complex interaction between a nickel layer and a 4H-SiC substrate under UVlaser irradiation since the early stages of the atomic inter-diffusion. An exhaustive description is still lacking in the literature. A multimethod approach based on Transmission Electron Microscopy, Energy Dispersive Spectroscopy and Diffraction (electron and X-ray) techniques has been implemented for a cross-correlated description of the final state of the contact after laser irradiation. They detailed the stoichiometry and the lattice structure of each phase formed as well as the Ni/Si alloy profile along the contact for laser fluences in the range 2.4-3.8 J/cm 2. To make a bridge between process conditions and post-process characterizations, time dependent ultra-fast phenomena (laser pulse ≈160ns), such as intermixing driven melting and Ni-silicides reactions, have been simulated by a modified phase fields approach in the proper many-compounds formulation. We disclose that raising laser fluence has multiple effects: 1) the thickness of the silicide layer formed at the interface with 4H-SiC expands; 2) the silicon content into the reacted layer increases; 3) a Ni 2 Si phase is promoted at the highest fluence 3.8 J/cm 2 ; 4) silicon atomic diffusion into a topmost residual nickel layer occurs, with the Ni/Si ratio increasing towards the contact surface.

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Structural characterization of in‐situ silicided contacts textured on p‐type [001] silicon

Cited by 5 publications

References 8 publications

Ni-Silicide Ohmic Contacts on 4H-SiC Formed by Multi Pulse Excimer Laser Annealing

Ni-Silicide Ohmic Contacts on 4H-SiC Formed by Multi Pulse Excimer Laser Annealing

Structural and Electrical Characterization of Ni-Based Ohmic Contacts on 4H-SiC Formed by Solid-State Laser Annealing

Inter-diffusion, melting and reaction interplay in Ni/4H-SiC under excimer laser annealing

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