Modeling high-concentration phosphorus diffusion in crystalline silicon

Abstract

Phosphorus diffusion in crystalline silicon in doping from a surface source at a temperature of 840 o C and a duration of 10 min has been modeled. Good agreement with experimental data has been obtained, which confi rms the adequacy of the employed model of high-concentration phosphorus diffusion. This model takes account of the drift of self-interstitials in the fi eld of internal elastic stresses.

A comprehensive model of high-concentration phosphorus diffusion in silicon

“…The drift of the nonequilibrium silicon self-interstitials in the field of elastic stresses leads to the supersaturation of the bulk of a semiconductor with self-interstitials and, consequently, to the enhanced diffusion of impurity atoms in the buried layers. The phosphorus concentration profiles calculated in [9,13] on the basis of these assumptions agree well with experimental data, including the formation of the "kink" and "tail" regions. The phenomena of oversaturation of the bulk of a semiconductor with self-interstitials [15] and enhanced impurity redistribution in the buried layers were also explained.…”

“…A detailed analysis of the basic models of the high-concentration diffusion of phosphorus is presented in [6,7,8,9]. It is assumed in the latest models that the diffusion of phosphorus atoms in the "tail" region occurs through the formation of the "phosphorus atom-silicon self-interstitial" pairs [7,9,10,11,12].…”

“…A detailed analysis of the basic models of the high-concentration diffusion of phosphorus is presented in [6,7,8,9]. It is assumed in the latest models that the diffusion of phosphorus atoms in the "tail" region occurs through the formation of the "phosphorus atom-silicon self-interstitial" pairs [7,9,10,11,12]. Unlike the diffusion mechanisms considered earlier, the mechanism of the formation of mobile "phosphorus atom-silicon self-interstitial" pairs makes it possible to explain many of the laws governing the processes of high-concentration phosphorus diffusion.…”

“…For example, it was supposed in [8,9,13] that internal elastic stresses are generated in the vicinity of the surface due to the lattice deformation. If the drift velocity of silicon self-interstitials in the field of elastic stresses is directed to the bulk of a semiconductor, the near-surface region is depleted of point defects, and a strong nonuniform distribution of self-interstitials can be formed without regard for the large migration length of these defects.…”

“…The phenomena of oversaturation of the bulk of a semiconductor with self-interstitials [15] and enhanced impurity redistribution in the buried layers were also explained. Unfortunately, in [13], the cluster formation was not taken into account, whereas in [9], the model of the formation of neutral phosphorus clusters was used. Therefore, only the initial stage of high-concentration phosphorus diffusion was simulated where cluster formation is negligible.…”