LIGHTLY NITRIDED GATE OXIDES FOR 0.25 MU-M CMOS

A N2O lightly nitrided gate dielectric technology is developed for 0.25 mum CMOS. Gate dielectric with a thickness of 7.5 nm is grown in a two-step furnace process. The first step is oxidation in diluted dry oxygen at 900-degrees-C, the second step is nitridation in pure N2O at 950-degrees-C.The use of lightly nitrided gate dielectrics improves the gate oxide quality and has no adverse effects on devices. Furthermore boron diffusion through thin gate oxide of BF2+ doped poly gates is suppressed. This makes it possible to use low energy BF2+ implants for shallow drain formation. The physical and electrical characterisation of MOS capacitors and 0.25 mum transistors will be presented.