Compensation of oxygen defects in La-silicate gate dielectrics for improving effective mobility in high-k/metal gate MOSFET using oxygen annealing process
Compensation of oxygen defects in La-silicate gate dielectrics for improving effective mobility in high-k/metal gate MOSFET using oxygen annealing process
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DOI：
10.1016/j.sse.2011.10.006
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发表时间：
2012-02-01
影响因子：
1.7
通讯作者：
Iwai, H.
中科院分区：
文献类型：
--
作者：
Kawanago, T.;Suzuki, T.;Iwai, H.
本文研究了用硅酸镧晶体与硅衬底直接接触的方法来补偿氧缺陷。氧的量通过在氧气氛中退火（氧退火）的温度和栅电极的厚度来控制。氧掺入引起的平带电压正移是硅酸镧晶体缺陷补偿的实验证据。最佳氧退火提供了VFB向正方向移动，而不增加等效氧化层厚度（EOT）。虽然氧退火降低了La-硅酸盐/Si界面的界面性能，但随后的形成气体退火（FGA）可以恢复界面性能。实验结果表明，硅酸镧晶体的VFB正位移即使在随后的FGA之后也是稳定的。硅酸镧中的氧供应预计即使在还原过程之后也能保持。用XPS成功地观察到氧掺入引起的费米能级向Si价带边的移动。此外，通过TEM观察和X射线光电子能谱分析，证实了氧退火后硅酸镧与硅衬底之间没有发生化学反应。实验证明，通过氧退火和FGA的结合，可以在不增加EOT的情况下提高有效空穴迁移率。(C)2011爱思唯尔有限公司版权所有。
Oxygen incorporation for compensation of oxygen defects is investigated with La-silicate dielectrics in directly contacted with the Si substrate. The amount of oxygen is controlled by the temperature of annealing in oxygen atmosphere (oxygen annealing) and the thickness of the gate electrode. The positive shift in flatband voltage (V-FB) by oxygen incorporation is an experimental evidence for defects compensation in La-silicate dielectrics. Optimum oxygen annealing provides the VFB shift toward positive direction without increasing equivalent oxide thickness (EOT). Although the oxygen annealing degrades the interfacial property at La-silicate/Si interface, subsequent forming gas annealing (FGA) can recover the interfacial property. It is experimentally revealed that the positive VFB shift of La-silicate dielectrics is stable even after subsequent FGA. The supplied oxygen in La-silicate is expected to maintain even after reducing process. Movement of Fermi level toward the Si valence band edge caused by oxygen incorporation is successfully observed by XPS. Moreover, no chemical reaction between La-silicate and Si substrate by oxygen annealing are confirmed from TEM observation and analyses of X-ray photoelectron spectra. It is experimentally demonstrated that effective hole mobility can be improved without increase in EOT by combination of oxygen annealing and FGA. (C) 2011 Elsevier Ltd. All rights reserved.