Interstitial-mediated arsenic clustering in ultrashallow junction formation

We propose a viable route for interstitial-mediated formation of arsenic-vacancy clusters that are primarily responsible for arsenic deactivation in the fabrication of ultrashallow junctions in Si, based on first-principles density functional calculations for the stability of arsenic-defect clusters. We present the atomic structures and binding energies of newly identified neutral arsenic-interstitial complexes (Asm In, m6 and n3), with comparison to the energetics of arsenic-vacancy complexes (Asm Vn, m6 and n2). Based on these results, we discuss the relative role of interstitials and vacancies in arsenic deactivation during ultrashallow junction formation.