高k栅介质/金属栅锑化镓MOS器件中的关键物理问题研究

With the continued scaling of feature size in devices, the use of advanced high k gate dielectric /metal gate stack to replace the traditional SiO2/ polysilicon gate stack has become the inevitable development of microelectronics technology. However, the introduction of high k dielectric and metal gate leads to the production of key physical problems, such as the degradation of carrier mobility and the effective work function shift induced by Fermi level pinning. This project intends to use ALD with in-situ passivation and self-cleaning effect to obtain quasi coherent GaSb interface, reduce the degree of disorder of interface, reduce the interface state density; Stabilizing the cubic phase of Hf-based gate dielectrics by doping of rare earth elements (Dy, Gd), improving the dielectric permittivity and dielectric shielding effect for Hf-based gate dielectrics, and inhibiting the ionized impurity scattering induced degradation of carrier mobility; preventing surface phonon scattering caused by surface roughness and interfacial defects by N doping; Reducing the high k/ metal gate interface state density by introducing metal nitride with thermal stability, realizing in adjusting the meatl gate work function, and inhibiting effective work function shift induced by Fermi level pinning effects . This research project is expected to obtain a thermodynamically stable, non Fermi level pinning high k material and the metal gate structure, provide experimental and theoretical basis for further research on the physical mechanism of carrier and device interface state density and scattering induced degradation in mobility, which has important scientific significance and practical value.

随着CMOS器件特征尺寸不断缩短, 利用高k栅介质/金属栅来取代SiO2/多晶硅栅结构成为微电子技术发展的必然。然而高k介质和金属栅引入导致了载流子迁移率退化及费米能级钉扎诱导的有效功函数偏移的关键物理问题。本项目拟采用原子层沉积技术的原位钝化和自清洁效应来获取准共格GaSb界面，减少界面无序度，降低界面态密度；通过稀土 (Dy, Gd）掺杂稳定铪基介质的立方相，提高铪基介质的介电常数和介电屏蔽效应，抑制由于电离杂质散射诱导的迁移率退化；通过N掺杂抑制由表面粗糙及界面缺陷所引起的表面声子散射；通过引入热稳定的金属氮化物栅，降低高k/金属栅界面态密度，实现金属栅功函数的调制，抑制由于费米能级钉扎效应诱导的有效功函数偏移。本项目的研究可望获得热力学稳定、无费米钉扎的高k栅介质与金属栅结构，并为深入研究界面态密度及散射诱导迁移率退化的物理机制提供实验基础和理论依据，有重要的科学意义和实用价值。

本项目以高k/金属栅结构构筑GaSb-MOSFET器件为导向，解决由于高k和金属栅的引入导致的载流子迁移率退化及费米能级钉扎诱导的有效功函数偏移的关键物理问题。项目采用原子层沉积技术沉积具有自清洁效应的AlON/Al2O3界面钝化层来获取准共格GaSb界面，减少界面无序度，降低界面态密度；通过稀土元素(Dy, Gd）掺杂稳定铪基栅介质的立方晶相，提高了铪基栅介质的介电常数和介电屏蔽作用，抑制了由于电离杂质散射诱导的迁移率退化；通过N掺杂抑制由表面粗糙及界面缺陷所引起的表面声子散射；通过引入金属氮化物栅，在高k/金属栅的界面引入介质覆盖层，通过界面偶极子调控栅结构的能带对准提高有效功函数，抑制由于费米能级钉扎效应诱导的有效功函数偏移。最终实现热力学稳定、无费米能级钉扎的高k材料与金属栅结构，构筑GaSb-MOSFET原型器件。围绕基金研究计划目标，在过去四年中，项目组成员系统开展了不同稀土元素掺杂铪基高k栅介质的制备、物性表征、界面的调控及MOS器件的性能优化；通过沉积自清洁效应的钝化层获取了准共格的MOS界面，发展了高载流子迁移率沟道基体上稀土元素掺杂的Hf基薄膜制备技成术，找出了满足未来栅介质材料要求的叠层材料；通过引入界面钝化技术，成功实现了热力学稳定，无费米能级钉扎的新型高k材料与叠层栅结构，构筑了高迁移率沟道衬底上叠层结构原型器件，解决了由于费米能级钉扎诱导的有效功函数的偏移问题。在本项目的资助下，共发表37篇国际期刊论文，其中通讯作者论文37篇。本课题的突破, 将为为高性能、快速新型MOSFET应用探索提供理论和实验依据，有重要的科学意义和实用价值。