Doped Silicon Oxynitride Gate Dielectric 0.13um Cmos Devices 1 / F Noise Characteristics Of The Study

With the development of CMOS technology in the deep sub-micro region, the traditional silicon dioxide gate dielectric is approaching to its physical limits.To reduce the gate oxide direct tunneling current and improve its ability to prevent boron penetration,it is bound to introduce new material.For 0.15μm to 0.065μm CMOS process,the traditional method is to use nitrogen-doped silicon oxide as gate dielectric.The incorporation of nitrogen will increase the gate dielectric constant,reduce short-channel devices on the gate oxide thinning dependence and gate direct tunneling current,improve gate dielectric anti-boron penetration ability.However,the traditional nitrogen-doped method uses nitrogen gas annealing at high temperature after silicon thermal oxidation,the doped nitrogen locates near the Si-SiO₂ interface.Because it changes the lattice structure near the silicon surface,some of the CMOS devices parameters show degradation. Especially,the nitrogen doping at the interface reduces part of device's reliability,and increases the device 1/f noise,which is especially detrimental to low-frequency analog applications.It is generally believed that CMOS 1/f noise is originated from the channel carrier density fluctuation or mobility fluctuation.The carrier density fluctuation depends on the Si-SiO₂ interface trap density and its energy in the band gap.The mobility fluctuation depends on the carriers scattering by phonon population.This thesis investigates different nitrogen-doped and anneal process gate dielectric impacts on 0.13μm CMOS 1/f noise.The dielectric's character is studied by testing the interface trap density,oxide total charge,oxide mobile charge,nitrogen concentration and its distribution profile.Then nitrogen-doped gate dielectric impact on CMOS 1/f noise is explored.Online monitor data shows that the nitrogen at the Si-SiO₂ interface increases the oxide total charge.In the same annealing condition,if the nitrogen-doped concentration is higher,or its distribution is more close to the interface,the oxide total charge will increase.The 1/f noise test results show that the gate dielectric with nitrogen at the Si-SiO₂ interface has significant impact on 0.13μm CMOS device 1/f noise.Its mechanism could be that the Si-N bond replaces the distorted Si-0 bond at Si-SiO₂ interface,and reduces the structural transition layer's stress,then changes the substrate surface lattice structure,enhances the carriers scattering by phonon population,and results in CMOS devices 1/f noise deterioration.A pre-nitrogen-doped process could change the nitrogen distribution from Si-SiO₂ interface to be near SiO₂ surface,which reduces 0.13μm CMOS device 1/f noise by 14～20dB.In nitrogen-doped gate dielectric process development,an online monitor of oxide total charge method could help on developing and selecting an optimized gate oxide process condition to improve the CMOS device 1/f noise,shortening the process development cycle and cost.