Characterization of defects in self-ion implanted Si using positron annihilation spectroscopy and Rutherford backscattering spectroscopy

Abstract

The behavior of vacancy-type defects and displaced Si atoms in Si(100) caused by self-ion implantation has been investigated by variable-energy positron annihilation spectroscopy and Rutherford backscattering spectroscopy/channeling. It is found that the recovery process of the defects strongly depends on the morphology of the implanted region. The divacancies produced by an implantation of 2×1014Si+⋅cm−2, which is less than the critical value required for amorphization, aggregate into large vacancy clusters by annealing at 300 °C. These vacancy clusters diffuse towards the surface at temperatures above 600 °C and anneal out at around 800 °C. The specimen implanted with 2×1015Si+⋅cm−2, in which a complete amorphization takes place in the damaged region, shows a different annealing characteristic. In the first stage (∼600 °C), the amorphous zone is transformed into crystalline material by solid phase epitaxial growth, although large vacancy clusters still remain. These agglomerate clusters continue to grow in a second annealing stage which takes place at around 700 °C. Annealing at 900 °C is required to eliminate these vacancy-type defects.

Activation Energies for the Formation and Evaporation of Vacancy Clusters in Silicon

“…1. This behavior is consistent with earlier observations on the stability of vacancy clusters up to 500 C and their annealing at higher temperatures [2,5,7].…”

“…However, Makhov and Lewis later suggested that vacancy clustering may well not lead to a clear change in PAS parameters, while the IR response is destroyed [6]. In another study of near-surface implantation-induced V 2 in Cz-Si it was found that if the ion dose is below the critical value for amorphization, vacancy clusters form after annealing at 300 C, which are stable up to 500 C but anneal out at 800 C [7].…”

Proportionality of vacancy concentration to ion implantation fluence

“…The existence of such a layer has been identified previously using PAS for implanted elements not lighter than fluorine, and is postulated to be due to diffusion of defects. 18,19 In addition, a layer with an electric field of Ϫ1 kV/cm was required near the surface ͑up to 1 m͒ to model the effect of the charge in the native oxide at the sample surface. Modeling of such fields has previously been discussed by Simpson et al 20 for Si wafers with various dopant concentrations and types.…”

Characterisation of Ion Implantation-induced Defects in Certain Technologically Important Materials by Positron Annihilation

“…The interested reader may look into review articles on this subject [31][32] and the references therein. A few references are cited at the end [33][34][35][36][37][38][39][40] .…”