Superficial-Enhanced Thermal Nitridation of SiO2 Thin Films

Superficial nitridation of thin (~13 nm) SiO2 films can be enhanced using annealing cycles of short duration at high temperatures (900°C-1200°C) in low pure anmmonia pressures (¿ 10^¿ mbar). The nitrided surface region is 3 to 4 nm wide with a rapidly decreasing nitrogen concentration versus depth. The experimental data suggest that amine NHx (0 ≪ × ≪ 3) species are essential in the nitridation process of SiO2 using NH3 gas. Al-gate/nitrided SiO2/Si(100)p capacitors have been prepared in situ or not. Electrical measurernents show that a low interface-state density (10¹⁰ to 10¹¹ eV ^¿1 cr^¿2), a good stability during electron injection due to a balance between trapping and detrapping in the nitrided region of SiO2 and a destructive breakdown field as high as 10 MV cm^¿1 can be achieved by optimizing nitridation conditions.