高迁移率Ge沟道器件研究进展

Research progress of high mobility germanium based metal oxide semiconductor devices

高迁移率Ge沟道器件由于其较高而且更对称的载流子迁移率,成为未来互补型金属-氧化物-半导体(CMOS)器件极有潜力的候选材料.然而,对于Ge基MOS器件,其栅、源漏方面面临的挑战严重影响了Ge基MOS器件性能的提升,尤其是Ge NMOS器件.本文重点分析了Ge基器件在栅、源漏方面面临的问题,综述了国内外研究者们提出的不同解决方案,在此基础上提出了新的技术方案.研究结果为Ge基MOS器件性能的进一步提升奠定了基础.

Germanium based metal oxide semiconductor（MOS） device has been a research hotspot and considered as a potential candidate for future complementary MOS（CMOS） technology due to its high and symmetric carrier mobility.However,the poor quality of gate dielectric/channel interface significantly restricts the performance of germanium based MOS devices.Besides,the solid-solubility and activation concentration of dopants in Ge are both quite low,and the dopants diffuse fast in Ge,which makes it difficult to achieve ultra-shallow junction with high dopant concentration,especially for Ge NMOS devices.To solve these problems,different techniques are proposed and overviewed.The proposed nitrogen-plasmapassivation method can effectively suppress the regrowth of germanium sub-oxide and reduce the interface state density.Thus the performance of the fabricated Ge NMOS device is significantly improved.To enhance the n-type dopant activation in Ge,the multiple implantation technique and the multiple annealing technique are proposed.High electrical activation over 1 × 10^（20） cm^（-3） is achieved,and the corresponding contact resistivity is reduced to 3.8 × 10^（-7） Ω·cm^2.Besides,the implantation after germanide（IAG） technique is first proposed to modulate the Schottky barrier height（SBH）.The record-low electron SBH of 0.10 eV is obtained by IAG technique,and the optimized process window is given.In addition,the poor thermal stability of NiGe restricts the further improvement of performance of Ge MOS device.P and Sb co-implantation technique and novel ammonium fluoride pretreatment method are proposed to improve the thermal stability of NiGe.The electrical characteristic of NiGe/Ge diode is also improved simultaneously.The results provide the guidelines for further enhancing the performances of germanium-based MOS devices.