Research And Fabrication Of SiGe MOS Devices With High K Gate Dielectrics

Compared with traditional Si substrates,SiGe materials use energy band engineering to reduce semiconductor energy band,so that Si can improve device performance without reducing device size.SiGe materials obtain very high mobility enhancement by introducing Ge elements into Si.At the same time,the stress of SiGe thin films can be adjusted by changing the proportion of Ge elements,and then the mobility and band gap of SiGe materials can be adjusted,which is compatible with the existing silicon technology,so it is favored by the industry.At present,the channel mobility of Si-based devices is declining seriously,so it is imperative to use high mobility channel materials.However,after introducing SiGe high mobility channel materials into Si-based devices,the interface quality drops sharply,and solving the problem of interface quality becomes the primary problem.It is difficult to find an effective passivation method for SiGe interface in traditional interface passivation methods.Among the new passivation methods,NH3 plasma has more advantages.NH3 plasma treatment has attracted much attention because of its excellent performance in Ge-based devices.In this paper,the effects of NH3 plasma on the interface composition and electrical parameters of high K/SiGe MOS are studied by designing experimental of different time,temperature and power.In view of the plasma damage to the interface,the ozone annealing experimental was compared with the NH3 plasma experiment to study the effects of three different passivation methods on interface components and electrical parameters.Three groups of ozone experimental were designed in different oxidation sequence,in which the deposition of high K dielectric layer was twice,and the thickness of Al2O3 in the first and second layers was changed at 300? for different time.The results show that the ozone experiment is the best when the thickness of the first layer of Al2O3 is 0.3nm and the annealing time is 30min,the density interface state is 4×1012eV-1cm-2,the hysteresis of the C-V curve was 13mV,and the EOT was 2.27nm,the device structure began to adopt non-planar process of three-dimensional gate structure.In contrast,ozone annealing is isotropic,can be applied to non-planar devices.