Modeling of the transient interstitial diffusion of implanted atoms during low-temperature annealing of silicon substrates

Abstract

It has been shown that many of the phenomena related to the formation of "tails" in the lowconcentration region of ion-implanted impurity distribution are due to the anomalous diffusion of nonequilibrium impurity interstitials. These phenomena include boron implantation in preamorphized silicon, a "hot" implantation of indium ions, annealing of ion-implanted layers et cetera. In particular, to verify this microscopic mechanism, a simulation of boron redistribution during low-temperature annealing of ion-implanted layers has been carried out under different conditions of transient enhanced diffusion suppression. Due to the good agreement with the experimental data, the values of the average migration length of nonequilibrium impurity interstitials have been obtained. It has been shown that for boron implanted into a silicon layer preamorphized by germanium ions the average migration length of impurity interstitials at the annealing temperature of 800 • C can be reduced from 11 nm to approximately 6 nm due to additional implantation of nitrogen. The further shortening of the average migration length is observed if the processing temperature is reduced to 750 • C. It is also found that for implantation of BF2 ions into silicon crystal, the value of the average migration length of boron interstitials is equal to 7.2 nm for thermal treatment at a temperature of 800 • C.

On concentration dependence of arsenic diffusivity in silicon

“…Indeed, in this case, a good agreement with experiment is observed in the whole region of high impurity concentration and only a small difference takes place in the region of low arsenic concentration which is less important for subsequent calculations of electrophysical parameters. Taking into account the results of [16], one can suppose that this difference appears due to the overlooked possibility of direct migration of arsenic interstitial atoms.…”

Simulation of boron diffusion during low-temperature annealing of implanted silicon

“…It was shown in [11,12,13] that the majority of the cases of "tail" formation in the low-concentration region of ion-implanted impurity distribution, including boron implantation in preamorphized silicon, is related to the phenomenon of a long-range migration of nonequilibrium impurity interstitials, and we can neglect channeling of a fraction of implanted atoms if ion implantation of In, P, and Ga is performed in a random direction or B is implanted in a preamorphized layer. In [14,15], a similar theoretical investigation and simulation of impurity redistribution were carried out for boron implantation in a random direction in the crystalline silicon.…”

Modeling of Ion Implantation and Rapid Thermal Treatments during the Formation of Active Regions of Submicron and Nanometer Silicon IС

“…Как было показано в работе [22], длиннопробеж-ная миграция неравновесных межузельных приме-сей, в частности бора и индия, является основным фактором в формировании «хвостов» распределений в области малой концентрации примеси как в случае ионной имплантации в кристаллический кремний, так и в случае внедрения примесей в предваритель-но аморфизованные слои кремния. В соответствии с этим, приведенная выше модель была усовершен-ствована: введен дополнительный поток диффузии неактивной межузельной примеси.…”