We propose a new parameter predicating transconductance (G
m) of the gate dielectric of nitrided SiO2 with the physical thickness below 1.1 nm for high-performance transistors. The 6 different type of nitrided SiO2 are formed using the plasma nitridation or nitric oxide (NO) gas annealing in conditions to adjust a optical thickness ranging 0.96 to 1.19 nm. The material property of nitrided SiO2 are analyzed by secondary ions mass spectroscopy (SIMS) and x-ray photoelectron spectroscopy (XPS). The MOSFET are fabricated using these gate dielectric and 90 nm generation CMOS technology. Then we find a good correlation between the maximum of G
m and the percentage of amount of N(SiN3)3 substructure at the total amount of NSi3 structure measured by XPS, rather than the total dose of nitrogen measured by SIMS.