4H-SiC MOSFET Source and Body Laser Annealing Process

Abstract

This work describes the development of a new post-implant crystal recovery technique in 4H-SiC using XeCl (l=308 nm) multiple laser pulses in the ns regime. Characterization was carried out through micro-Raman spectroscopy, Photoluminescence (PL), Transmission Electron Microscopy (TEM) and outcomes were than compared with 1h thermally annealed at 1650-1770-1750 °C P implanted samples (source implant) and P and Al implanted samples for 30 minutes at 1650 °C (source and body implants). Experimental results demonstrate that laser annealing enables crystal recovery in the energy density range between 0.50 and 0.60 J/cm2. Unlike the results obtained with thermal annealing where stress up to 172 Mpa and high carbon vacancies (Vc) concentration is recorded, laser annealing provides almost stress free samples and much less defective crystal avoiding intra-bandgap carrier recombination. Implant was almost preserved except for step-bouncing and surface oxidation phenomena leading to surface roughening. However, the results of this work gives way to laser annealing process practicability for lattice damage recovery and dopant activation.

Silicon and Silicon Carbide Recrystallization by Laser Annealing: A Review

“…Moreover, this process can also be useful for the ohmic contact formation process in SiC Schottky diodes, causing a negligible impact on the device's front side [15,16]. The laser annealing process has also been used to activate doping ions in the source and drain region of MOSFET to avoid damage to the channel region induced by global device heating processes such as rapid thermal annealing (RTA) [17][18][19]. A scheme of laser annealing processes in semiconductor devices is reported in Figure 1.…”