硅基绝缘层上高迁移率锗与锗锡沟道CMOS器件及可靠性研究

This project, aiming to the fabrication of high mobility Ge and GeSn channel CMOS devices on insulator, focuses on the fundamental problems, including the mechanism of interface states generation, cause of increasing of equivalent oxide thickness (EOT), and mechanism of carrier mobility enhancement. The research on material preparation, exploration of key process modules, and design and fabrication of devices will be developed. Ge and GeSn channel materials on insulator suitable for the realization of fully-depleted CMOS devices will be achieved by epitaxial growth and wafer bonding techniques. We will examine in depth the surface passivation methods to reduce the density of interface states (Dit); demonstrate the proper high-κ gate dielectric materials and structures by combining gate dielectric growth process, and defect characterization techniques; and optimize the channel structures based on the investigation of the impacts of strain, surface orientation, Sn composition, and channel doping on the carrier mobility. Ge and GeSn MOS structures with low Dit, ultrathin EOT, and high carrier mobility will be realized. By exploring the methods for reducing the short channel effects and studying the typical reliability issues of high mobility transistors with narrow band gap, high performance fully-depleted Ge and GeSn CMOS devices on insulator will be demonstrated. By the study of this project, tons of theory and technology achievements will be obtained, which contribute greatly to the development of high mobility channel CMOS devices in China.

本项目以探索并实现硅基绝缘层上高迁移率锗与锗锡沟道CMOS器件为目标，围绕界面态产生机制、等效氧化层增厚机理及迁移率增强机制等关键科学问题，开展材料生长、关键工艺探索、器件的设计与实现及性能表征等方面的研究。探索SOI上直接外延生长和键合转移方法，实现绝缘层上锗与锗锡CMOS器件沟道材料。深入探索新的器件表面钝化方法，进一步降低界面态密度；探索先进的高κ栅介质生长技术和缺陷表征方法，实现高质量的高κ栅介质；进一步探索应变、晶面取向、锡组分及沟道掺杂对载流子迁移率的增强作用，实现最优沟道结构；最终获得低界面态密度、超薄等效氧化层、高载流子迁移率的锗与锗锡MOSFET。进一步探索抑制短沟道效应的有效方法，重点解决基于窄禁带、高迁移率材料CMOS器件可靠性难题，最终实现硅基绝缘层上高性能、全耗尽型锗与锗锡CMOS器件。通过本课题的研究，为我国高迁移率沟道CMOS器件的发展提供理论指导和技术支撑。

本项目深入研究硅绝缘层上高迁移率沟道MOSFET器件制备工艺、电学特性和可靠性问题，并开展了超低功耗锗负电容晶体管（NCFET）和新型类铁电非易失晶体管（NVFET）研究。.1）利用Si2H6低温钝化工艺实现了硅衬底上应变GeSn沟道pMOSFET，空穴迁移率峰值达到500 cm2/V·s。.2）实现超高κ ZrO2栅介质Ge pMOSFET，获得小于1纳米的等效电容层厚度和最高的高场迁空穴有效迁移率，反型电荷密度1013 cm−2时，空穴迁移率达到190 cm2/V•s。.3）实现了ZrO2栅介质Ge nMOSFET，反型电荷密度5×1012 cm−2时，电子迁移率比Si器件提升 50%。.4）在SOI上外延生长超薄的单晶Ge沟道，并制备pMOSFET。和弛豫Si器件相比，带有单轴应变Ge pMOSFET空穴迁移率峰值提升了18倍，达到897 cm2/V•s。.5）研究不同退火温度和不同栅介质厚度下Ge pMOSFET和nMOSFET的NBTI特性和PBTI特性，理论上分析了器件退化机制。.6）GeOI衬底上制备了氧化锆栅介质的Ge pFinFET器件，在反型层电荷密度为5×1012 cm-2时，空穴迁移率比硅器件提高了60%，并进一步发现[110]沟道方向的器件具有比[100]沟道方向的器件更高的载流子迁移率和电流密度。并在理论上确定晶面曲线和沟道方向获得最大迁移率的最优值，同时研究沟道厚度对迁移率的影响。.7）实验研究探索NCFET典型电学特性，观测到了负电容模型预测的栅电容尖峰效应；在器件输出特性曲线中观测到了负微分电阻效应，该工作成为后续大量理论和实验研究NCFET器件和电路应用的基础。.8）实验发现了非晶类铁电栅介质，并实现了非易失场效应晶体管（NVFET）存储器件和神经突出器件，阐明了产生类铁电特性的物理机制。非晶Al2O3 NVFET实现小于2 V的操作电压，远低于多晶掺杂HfO2铁电器件。该结构有利于实现FinFET或者Nanosheet FET等先进器件结构的嵌入式存储器或者负电容器件。.本项目的研究结果，为高迁移率Ge沟道MOSFET在CMOS应用提供的技术参考和支持！