Dopant profile engineering using ArF excimer laser, flash lamp and spike annealing for junction formation

Abstract

The aim of this study is to evaluate the feasibility to integrate excimer laser annealing (ELA) into the process flow to achieve higher doped and ideally box shaped profiles. The recrystallization, dopant distribution, and activation of boron or arsenic shallow implantations in germanium pre-amorphized silicon are investigated by comparing argon fluoride ELA, flash lamp annealing, and spike annealing. As a result the complete amorphous Silicon layer melts with ELA above 400 mJ/cm2 and subsequently recrystallizes taking the silicon substrate as crystal seed (ELA Liquid Phase Epitaxial Regrowth). The implanted dopants are uniformly distributed in the melted region. We achieved four to ten times sharper boron profiles and a dopant activation of up to 4×1020 cm-3 An active arsenic concentration of 1.6×1020 cm-3 was demonstrated.