Scott A. Harrison

Structure, stability, and diffusion of arsenic-silicon interstitial pairs

Recent experimental studies [A. Ural, P. B. Griffin, and J. D. Plummer, J. Appl. Phys. 85, 6440 (1999); R. Kim, T. Hirose, T. Shano, H. Tsuji, and K. Taniguchi, Jpn. J. Appl. Phys. 41, 227 (2002); S. Solmi, M. Ferri, M. Bersani, D. Giubertoni, and V. Soncini, J. Appl. Phys. 94, 4950 (2003)] have suggested the importance of Si interstitials in As transient enhanced diffusion during pn junction formation in silicon. Using density functional theory calculations within the generalized gradient approximation, we have examined the structure, stability and diffusion of As–Sii pairs. For the negatively charged As–Sii pair, we find a minimum energy structure in which the As atom bridges two approximate lattice Si atoms, while for the neutral and positively charged As–Sii we find the lowest energy structure is comprised of an As and Sii pair that is aligned in the [110] direction while sharing a lattice site. Our results suggest that in n-type extrinsic regions the diffusion of −1 charged As–Sii pairs will be preva...

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 (As m I n , m ≤ 6 and n ≤ 3), with comparison to the energetics of arsenic-vacancy complexes (As m V n , m ≤ 6 and n ≤ 2). Based on these results, we discuss the relative role of interstitials and vacancies in arsenic deactivation during ultrashallow junction formation.

Origin of vacancy and interstitial stabilization at the amorphous-crystalline Si interface

Using plane-wave pseudopotential density functional theory calculations, we have investigated the behaviors of neutral interstitials and vacancies at the amorphous-crystalline (a–c)Si interface. A continuous random network model is employed in the construction of defect-free a-c interface structure. We find that both vacancies and interstitials prefer to reside on the amorphous side of the interface. In both cases, the most stable defects occur 3–4A from the a-c interface. Vacancy stabilization is found to be due to strain relief provided to the substrate lattice while interstitial stabilization is due largely to bond rearrangement arising from interstitial integration into the substrate lattice. We also discuss the effect of the “spongelike” behavior of the amorphous phase toward native defects on ultrashallow junction formation in the fabrication of ever-shrinking electronic devices.

Prediction of B–Sii–F complex formation and its role in B transient enhanced diffusion suppression and deactivation

Gradient corrected density functional calculations are used to examine the interaction of boron and fluorine in crystalline silicon. We have determined the formation of a stable boron-silicon-fluorine (Bs–Sii–Fi) complex in which the B and F atoms are indirectly connected through a Si interstitial, while the direct B–F bonding interaction is likely to be insignificant. Depending on dissociation reactions, the binding energy of the Bs–Sii–Fi complex is predicted to be 1.82–1.91eV relative to the corresponding products in the neutral state. We also show the atomic structure and bonding mechanism of Bs–Sii–Fi and discuss the potential role of Bs–Sii–Fi formation in B transient enhanced diffusion suppression and deactivation.