2010 Fiscal Year Final Research Report
Understanding of mechanisms dominating inversion-layer mobility in strained-Si MOSFETs and establishment of guideline for the mobility enhancement
| Project/Area Number |
20246055
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Electronic materials/Electric materials
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| Research Institution | The University of Tokyo |
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Principal Investigator |
TAKAGI Shinichi The University of Tokyo, 大学院・工学系研究科, 教授 (30372402)
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| Co-Investigator(Renkei-kenkyūsha) |
MITSURU Takenaka 東京大学, 大学院・工学系研究科, 准教授 (20451792)
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| Project Period (FY) |
2008 – 2010
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| Keywords | MOSFET / ひずみSi / 移動度 / 表面ラフネス / クーロン散乱 / 界面準位 / 酸化膜信頼性 |
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| Research Abstract |
We have evaluated surface-roughness-limited mobility of strained-Si MOSFETs and amount of surface roughness at the MOS interfaces. As a result, it has been found that bi-axial tensile strain increases the electron mobility, while it slightly decreases the hole mobility. Also, we have proposed a novel method to accurately evaluate the shape of the SiO2/Si interface roughness and the auto-correlation function by using high resolution Transmission Electron Microscope (TEM). It has been found that the mobility determined by the extracted auto-correlation is in good agreement with the experimental mobility for both electrons and holes. In addition, we have experimentally observed that the strained-Si MOS interfaces smaller densities of interface states generated by Fowler-Nordheim stress, attributed to the reduction in roughness of strained-Si MOS interfaces.
Furthermore, the increase in the bi-axial tensile strain strained-Si p-MOSFETs leads to the increase in Coulomb-scattering-limited hole mobility due to MOS interface charges, while it leads to the decrease in Coulomb-scattering-limited mobility due to substrate impurities. This dependence is opposite to that of the electron mobility in strained-Si n-MOSFETs. These strain dependencies of the Coulomb scattering mobilities can be systematically understood from the viewpoint of the subband structure modulation of electron and hole inversion layers due to tensile strain.
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[Book] Devices Structures and Carrier Transport Properties of Advanced CMOS using High Mobility Channels, Electronic Device Architectures for the Nano-CMOS Era-From Ultimate CMOS Scaling to Beyond CMOS Devices, chapter 32008
Author(s)
S.Takagi, T.Tezuka, T.Irisawa, S.Nakaharai, T.Numata, K.Usuda, N.Sugiyama, M.Shichijo, R.Nakane, S.Sugahara
Total Pages
81-103
Publisher
Pan Stanford Publishing
