LOCALIZATION OF NITROGEN ATOMS IN Si–SiO2 STRUCTURES

Abstract

Studies have been carried out by time-of-flight mass spectroscopy of secondary ions of subcutaneous silicon oxides, nitridation by ion implantation (II) or nitrided by high-temperature annealing in an atmosphere of N2. Nitrogen AI was produced with an energy of 40 keV, implantation doses of 2,5×1014 and 1×1015 cm-2. High-temperature annealing was carried out at a temperature of 1200 C for 2 hours or at 1100 C for 30 minutes. It is established that at the Si–SiO2 interface, after nitriding by II or high-temperature annealing, a maximum with a high concentration of nitrogen atoms is observed. It is shown that after conducting nitrogen AI with a dose of 2,5 ×1014 cm-2 through a protective SiO2 with a thickness of 23 nm and RTA at 1000 C for 15 seconds, the main maximum of nitrogen distribution (1×1019 cm-3) is observed at the Si–SiO2 interface, which indicates the presence of a saturation concentration of the Si–SiO2 interface. A charge-based one-dimensional Fermi model is proposed to describe the accelerated diffusion of nitrogen atoms. The main mechanism is the diffusion of interstitial atoms, which can occur with the preliminary displacement of nodal nitrogen atoms by their own embedding atoms. It is shown that nitrogen atoms can act as annihilation centers of point defects in the silicon crystal lattice.