Simulations of the Ultra-Fast Kinetics in Ni-Si-C Ternary Systems under Laser Irradiation

Abstract

We present a method for the simulation of the kinetic evolution in the sub µs timescale for composite materials containing regions occupied by alloys, compounds, and mixtures belonging to the Ni-Si-C ternary system. Pulsed laser irradiation (pulses of the order of 100 ns) promotes this evolution. The simulation approach is formulated in the framework of the phase-field theory and it consists of a system of coupled non-linear partial differential equations (PDEs), which considers as variables the following fields: the laser electro-magnetic field, the temperature, the phase-field and the material (Ni, Si, C, C clusters and Ni-silicides) densities. The model integrates a large set of materials and reaction parameters which could also self-consistently depend on the model variables. A parameter calibration is also proposed, specifically suited for the wavelength of a widely used class of excimer lasers (? = 308 nm). The model is implemented on a proprietary laser annealing technology computer-aided design (TCAD) tool based on the finite element method (FEM). This integration allows, in principle, numerical solutions in systems of any dimension. Here we discuss the complex simulation trend in the one-dimensional case, considering as a starting state, thin films on 4H-SiC substrates, i.e., a configuration reproducing a technologically relevant case study. Simulations as a function of the laser energy density show an articulated scenario, also induced by the variables’ dependency of the materials’ parameters, for the non-melting, partial-melting and full-melting process conditions. The simulation results are validated by post-process experimental analyses of the microstructure and composition of the irradiated samples.

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

“…Ni layers, 100 nm-thick, have been deposited on grinded C-side 4H-SiC surfaces by DC sputtering in Ar ambient at a base pressure of 1 x 10 -3 mbar. Since the silicide reaction is sensitive to impurities at the interface between Ni and substrate [12,30,31], an in-situ sputter [32] has been integrated and calibrated in the LIAB computation tool (see Ref. [33] for the detailed presentation of the approach).…”

“…The evolution framework derived from the simulations can be qualitatively separated in three main regimes: sub-melting, partial-melting, full-melting characterized by different features [32]. Hereby we summarize these features: a) In the sub-melting regime, i.e.…”

“…Hereby we summarize these features: a) In the sub-melting regime, i.e. the low fluence range, the systems remain solid during the whole heating/cooling cycle and the main phenomena (both boosted by the temperature increase) are the intermixing, which starts at the Ni/4H-SiC interface, and the subsequent early and limited silicide formations if the Si density is above solid solubility threshold [32].…”

Microstructural Evolution of Ni-SiC Composites Manufactured by Spark Plasma Sintering

“…[25] Several papers analyzing the Ni-SiC behavior at elevated temperatures can be found in the literature. [26][27][28][29][30] The investigations mainly concern the post-manufacturing thermal treatment of Ni-SiC systems and its effect on the structural evolution and physical properties. There are many sophisticated experimental tools applied to describe the correlation between the material structure, microstructure, and properties vs. temperature.…”

Effects of Excimer Laser Irradiation on the Morphological, Structural, and Electrical Properties of Aluminum-Implanted Silicon Carbide (4H-SiC)

“…In recent years, most of the experimental and theoretical studies dealing with laser annealing treatments in 4H-SiC-technology have been focused to the formation mechanisms of back-side Ohmic contacts, with particular attention to nickel silicide. − However, less work has been reported on the effect of laser annealing directly on ion-implanted SiC layers. The earliest literature on this subject reported on the pulsed ultraviolet (UV) excimer laser annealing effects in 6H-SiC-implanted layers, with the aim of quantifying a possible dopant activation. − As an example, Ahmed et al investigated the possible dopant activation produced by pulsed excimer laser exposure of N- and Al-implanted 6H-SiC, obtaining unrealistic activation levels (more than 100%) by means of point-contact current–voltage (PCIV) measurements, thus indicating the difficulty in the assessment of the dopant activation .…”