Impact of impurities on leakage current induced by High-Energy Density Pulsed Laser Annealing in Si diodes
Résumé
Pulsed Laser Annealing (PLA) offers significant advantages over conventional thermal processes for semiconductor device fabrication. Notably, it can provide ultrafast (~ns) and high-temperature (>1000°C) profiles. When the maximum temperature exceeds the melting point, a solid-liquid phase transition occurs, followed immediately by rapid recrystallization. This unique annealing mechanism raises questions about dopant diffusion and residual defects not only in the recrystallized region but also just below it. Since power devices require micrometer-sized junctions, high laser energy densities (ED) are necessary. These ED have been shown to promote the incorporation of complex impurities from the surface and the creation of defects at the liquid/solid interface. This paper reports on the impact of laser annealing at high energy densities (up to 8.0 J/cm²) on leakage current using Schottky and PN diodes and DLTS measurements. Various laser annealing conditions were used, including energy densities ranging from 1.7 to 8.0 J/cm² and 1 to 10 pulses. Our results suggest that the solubility of vacancies in silicon is fixed by the maximum temperature reached and the energy density. Increasing the number of laser pulses enables one to reach the maximum vacancy concentration and promote diffusion towards the surface. Concurrently, the diffusion of complex impurities into the melted region enables coupling between the two defect types, creating trap centers responsible for degrading the leakage current.
| Origine | Fichiers produits par l'(les) auteur(s) |
|---|---|
| Licence |