N2O nitrided gate dielectric technology for 0.25 mu m CMOS

A technology for thin N₂O nitrided gate oxide was developed for 0.25 mu m CMOS. A gate dielectric of 7.5 nm thickness was grown using 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 improved the gate oxide quality and did not degrade the MOS device properties. Furthermore, boron diffusion through the thin dielectric of BF₂ doped poly gates was suppressed by N₂O nitridation.