Spatial position of deep levels near the Si—SiO2interface of ion implanted MOS structures

Measurements of the threshold voltage shift of MOS transistors in dependence on the implantation energy are correlated with calculations of the number of ions implanted in a small Si-layer beneath the gate oxide. The thickness of this layer and the number of deep levels per implanted ion is determined. The energy level ETof the implanted³⁵Cl⁺in the silicon is approximately 0.85 eV below the conduction band.