Dose–time relation in BF3 plasma immersion ion implantation

Semiconductor devices with shallow junctions can be fabricated using plasma immersion ion implantation. In this technique BF3 gas has been used as the boron dopant source due to its low toxicity. Not only are ions implanted but, because of the fluorine ions, there is etching and deposition at the wafer surface. Therefore, the relationship between total dose and processing time is not straightforward. The etching rate of silicon and SiO2 during plasma immersion ion implantation ~PIII! has been studied by Jones et al. using a simple mathematical model for the implant profile. However, no comparison of experimental results was made with this model. In this article the etching rate of silicon and SiO2 is measured under well-controlled conditions and a new dose-time relation is also derived. The result obtained by this relation is in very good agreement with the measured data.