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CMOSデバイスに向けたゲルマニウム基板上高誘電率絶縁膜ゲートスタック技術

CMOS器件用锗衬底高介电常数绝缘膜栅叠层技术

基本信息

批准号：
12J09309
负责人：
張睿
金额：
$ 1.28万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for JSPS Fellows
财政年份：
2012
资助国家：
日本
起止时间：
2012 至 2013
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12J09309/
关键词：
Ge MOSFETs High field mobility Carrier scattering ゲルマニウムゲートスターク MOS界面 MOSFET

项目摘要

Ge channel is one of the most promising solution for CMOS devices in post-Si age. Mobility enhancement is the most critical issue limiting the application of Ge MOSFETS. Recently, although many progresses have been achieved for high mobility Ge MOSFETs, mobility degradation in high normal field region is still severe which strongly reduces the ON state current in Ge MOSFETs. The mechanism of this phenomenon is not clear yet, in spite of importance. Therefore, in our research the physical origins causing high normal field mobility degradation were systematically investigated. Through the evaluation of Hall mobility in Ge MOSFETs, it is found that large amount of surface states exist inside valence and conduction band of Ge, which results in significant decrease of mobile carrier concentration in the channel and rapid reduction of effective mobility of Ge MOSFETs.Additionally, it is confirmed that the surface states inside conduction band of Ge can be passivated by annealing the Ge nMOSFETs in atomic deuterium ambient. Besides of surface states, it is also confirmed that the surface state roughness scattering dominates the mobility in high normal field for Ge MOSFETs, similar with the situation in Si MOSFETs. With decreasing the post oxidation temperature, the surface roughness at GeOx/Ge interfaces can be sufficiently reduced without losing the superior electrical passivation much. As a result, around 20% and 25% mobility enhancement can be realized for Ge pMOSFETs and nMOSFETs, respectively, in a high normal field region of N_s=10^<13> cm^<-2> by reducing the post oxidation temperature from 300℃ down to room temperature.

Ge沟道是后硅时代最有前途的解决方案之一。迁移率的提高是限制Ge MOSFET应用的最关键问题。近年来，尽管高迁移率Ge MOSFET已经取得了许多进展，但高法向场区的迁移率退化仍然很严重，这大大降低了Ge MOSFET的导通态电流。尽管这一现象很重要，但其机制尚不清楚。因此，在我们的研究中，系统地研究了导致高法向场迁移率退化的物理根源。通过对Ge MOSFET的霍尔迁移率的研究，发现在Ge的价带和导带内存在大量的表面态，导致沟道中的载流子浓度显著降低，Ge MOSFET的有效迁移率迅速降低。此外，还证实了Ge导带内的表面态可以通过在氢原子环境中的退火来钝化。除表面态外，Ge MOSFET的高正场迁移率主要受表面态粗糙度散射的影响，这与Si MOSFET的情况类似。随着后氧化温度的降低，GeOx/Ge界面的表面粗糙度可以得到充分的降低，而不会失去更好的电钝化效果。结果表明，通过将后氧化温度从30 0℃降低到室温，在N_S=10^&lt；13&gt；-2&gt；的高场下，Ge pMOSFET和nMOSFET的迁移率分别提高了约20%和25%。