Empirical modell of low ohmic Ni contact formation on n-type 4H-SiC by laser annealing
Internally funded project
Start date : 01.03.2017
Project details
Short description
In this work, nickel-based ohmic
contacts were fabricated on the C-side of n-doped 4HSiC substrates using
a short-time pulse laser, electrically characterized and analytically
investigated to understand the underlying formation mechanisms compared
to classical RTP. To obtain conclusions about the prevailing
temperatures from the laser fluence used during alloying, a thermal
simulation was created in COMSOL. This makes it possible to describe the
silicidation mechanisms during laser processing in a
temperature-dependent and thus system-independent manner.
For the fabrication of the ohmic contacts, the focus of the work was on the use of nickel layers, since these represent the most common metallization for low-resistance contacts on n-doped 4H-SiC. In order to evaluate the influence of different laser parameters on the contact formation mechanisms and the electrical properties of ohmic contacts, several sets of samples were prepared. The variation of the laser fluence was in the focus of the work, but also investigations on different surface pre-treatments, laser pulse durations, pulse overlaps and metallization compositions were performed.
Scientific Abstract
Im Rahmen dieser Arbeit wurden nickelbasierte ohmsche Kontakte auf der C-Seite von n-dotierten 4H-SiC-Substraten unter Verwendung eines Kurzzeitpulslasers hergestellt, elektrisch charakterisiert und analytisch untersucht, um die zugrundeliegenden Bildungsmechanismen im Vergleich zum klassischen RTP zu verstehen. Um von der beim Einlegieren verwendeten Energiedichte Rückschlüsse auf die vorherrschenden Temperaturen zu erhalten, wurde eine thermische Simulation in COMSOL erstellt. Damit ist es möglich die Silizidierungsmechanismen während der Laserbearbeitung temperaturabhängig und damit anlagenunabhängig zu beschreiben.
