反应溅射的TaN金属栅的材料性质和有效功函数研究

本文研究了反应溅射的TaN金属栅的电阻,晶体结构和有效功函数(EWF). 原始生长的TaN薄膜具有fcc 结构。经过900 oC后金属退火（PMA）,反应溅射时的氮气流量大于6.5 sccm的TaN仍保持fcc 结构,而反应溅射时的氮气流量小于6.25 sccm的TaN显示了微结构的变化。接着测量了用TaN作为电极的SiO2 和HfO2 栅平带电压随TaN反应溅射时氮气流量的变化。结果显示在介电质和TaN的界面会形成一个电偶矩,它对EWF的贡献会随TaN中的Ta/N比、介质层的性质和 PMA条件不同而变化。     

Comparison between N_2 and O_2 anneals on the integrity of an Al_2O_3/Si_3N_4/SiO_2/Si memory gate stack

In this paper the endurance characteristics and trap generation are investigated to study the effects of different postdeposition anneals(PDAs) on the integrity of an Al2O3/Si3N4/SiO2/Si memory gate stack. The flat-band voltage(Vfb)turnarounds are observed in both the programmed and erased states of the N2-PDA device. In contrast, this turnaround is observed only in the erased state of the O2-PDA device. The Vfbin the programmed state of the O2-PDA device keeps increasing with increasing program/erase(P/E) cycles. Through the analyses of endurance characteristics and the low voltage round-trip current transients, it is concluded that in both kinds of device there are an unknown type of pre-existing characteristic deep traps and P/E stress-induced positive oxide charges. In the O2-PDA device two extra types of trap are also found: the pre-existing border traps and the P/E stress-induced negative traps. Based on these four types of defects we can explain the endurance characteristics of two kinds of device. The switching property of pre-existing characteristic deep traps is also discussed.