Enhanced ‘‘tail’’ diffusion of phosphorus and boron in silicon: Self-interstitial phenomena

Abstract

It is well known that high surface concentration phosphorus diffusion leads to deeply penetrating ‘‘tails’’ in its concentration profile. At 700 °C the tail diffusivity exceeds that of low concentration phosphorus by a factor of 1000. Less spectacular, but very significant tailing also affects boron, making the conventional models contained in commonly available process simulation programs quite inaccurate for high concentrations of boron. We show that the observed tailing can be accounted for by a model whose central assumption is the local equality of dopant and oppositely directed defect fluxes.

Pair diffusion and kick‐out: Contributions to diffusion of boron in silicon

“…29,30,34 Evidence for this view came mainly from surface oxidation experiments in which Si interstitials that were injected into the bulk enhanced boron diffusion. 13 Si interstitials are well known to mediate boron motion, and formation of a complex is consistent with this fact.…”

Set of equations for stress-mediated evolution of the nonequilibrium dopant-defect system in semiconductor crystals

“…For example, one can simulate the formation of the immobile peak in high concentration region and "broadening" of boron concentration profiles in low concentration regions during annealing of the ion-implanted layers. However, as distinct from equations used in [1][2][3][4][5][6][7][8], the effect of elastic stress can be taken into account. For simulation of stress-mediated coupled diffusion of dopant atoms and point defects, the expressions describing spatial distributions of effective drift velocity of mobile species in the stress field should be added to the Eqs.…”

“…Together with diffusion of "dopant atom-vacancy" pairs, the diffusion of the pairs "dopant atom-self-interstitial" is considered in [3][4][5][6][7][8]. For example, in [3] diffusion of the pairs "dopant atom-vacancy" and "dopant atom-self-interstitial" is described along with the diffusion of vacancies and self-interstitials in different charge states.…”

“…To describe evolution of a dopant-defect system during thermal processing, a number of models of coupled diffusion have been developed in the last few years (see, for example, [1][2][3][4][5][6][7][8]). Together with diffusion of "dopant atom-vacancy" pairs, the diffusion of the pairs "dopant atom-self-interstitial" is considered in [3][4][5][6][7][8].…”

Gettering Processes and the Role of Extended Defects

“…For P diffusion it is established that self-interstitials are injected due to dissociation of PI pairs -one of the mobile species mediating P diffusion -in the kink region of typical phosphorus concentration profiles [92][93][94]. Assuming quasi-stationary conditions for the interstitial metal species, Spiecker et al [63] have calculated the PDG efficiency G surf as the ratio of total metal concentrations at the Si/PSG interface and in the bulk as…”