锗及应变锗MOS器件高场迁移率的提高及相关散射机理研究

随着现代硅集成电路技术进入亚32nm时代，传统的技术发展模式已不能再有效地提高场效应晶体管器件以及电路的整体性能。一些新的技术已被提出，主要包括新沟道材料，应变技术和新器件结构。锗因其同时具有较高的电子和空穴迁移率作为新沟道材料而备受瞩目。然而，到目前为止国际上大部分锗 MOS器件的研究都集中在工艺优化上，尚未对其散射机理进行深入的研究。同时，虽然锗MOS器件的峰值迁移率已经获得较高的数值，但是在高电场下的迁移率仍然偏低。而在实际应用中，真正起作用的是高场下的迁移率。已有的研究表明，减小MOS界面粗糙度并不能很有效地提高Ge器件的高场迁移率，这其中的原因尚不清楚。此外，如何有效运用应变技术和新器件结构（GOI）提高Ge器件性能这一问题在器件物理理解上和实验验证上都尚未很好地被解决。本项目将结合应变技术和GOI新结构的应用对Ge MOS器件中高场载流子迁移率的提高和散射机理进行深入的研究。

With the Si CMOS technology enters into sub-32nm nodes, the conventional device scaling could not enhance the device performance any more. Consequently, some new technology boosters have been proposed, mainly including new channel materials, the strain technology and the new device structure. Ge channel is one of the promising performance boosters for replacing Si for the sub-20nm CMOS technology nodes. Although the origin motivation for studying Ge MOS devices is mainly because of its high hole mobility, recently, there have more and more reports about the high electron mobility in Ge for the possibility of Ge-based CMOS technology(both nMOS and pMOS devices using Ge channel. In addition, most reports about Ge MOS devices so far are about the process optimization, specially the MOS interface properties improvements. There is few study about the detailed physical understanding on scattering mechanisms in the Ge MOS devices. On the other hand, although there have been some works about the high peak mobility of Ge MOS devices, the high-field mobility, which is really important in the real device application, is still with a relatively low value. Also, it has been shown that MOS interface roughness reduction is not an effective way to enhance the high-field mobility for Ge MOS devices. The physical mechanism is still unclear to us. In addition, how to utilize the strain technology and new device structure to enhance Ge MOS device performances is also not well physically understood and experimentally demonstrated. In this study, we will comprehensively study the high field mobility in Ge MOS devices by utilizing the strain technology and new device structure.