Langmuir Adsorption and Reaction Control in Process for Fabrication of Ultrasmall Group IV Semiconductor Devices

本课题以建立超小型IV型半导体器件的制备工艺技术为目标，开展了包括原子层生长、刻蚀等朗缪尔型吸附/反应工艺的基本原理和应用的深入研究。在原子控制工艺方面，利用低温超净反应气氛、氙灯闪光加热和ECR等离子体低能离子辐照，实现了Si、Ge的原子层生长、400ﾟC下NH_3的原子层氮化、500~600ﾟC下CH_4的原子层碳化、SiH_3CH_3在Si和Ge上的原子层吸附、P在Si和Ge上的原子层掺杂、SiGe系统的部分原子层刻蚀、氮化硅的原子层角色共享刻蚀、通过交替供给WF6和SiH4，研究了低温选择性沉积W的吸附和反应过程。这些原子有序过程均用朗缪尔型简单吸附和反应方程式描述，为高精度控制过程奠定了基础。在器件制作工艺方面，我们利用源/漏区的超自对准超低结形成技术制作了超小型MOSFET，并以SiGe外延层为沟道制作了MOSFET。此外，我们还开发了每一种工艺，如选择性外延SiGe和原位重掺杂P和B，高选择性各向异性腐蚀重掺杂多晶硅，通过选择性生长W来降低源漏电阻，以及通过这些单独工艺的组合来实现整个超小型器件工艺。这些研究成果为IV族半导体超小型器件制造技术的研究提供了基础。

In this scientific research, to establish fabrication process technology of ultrasmall group IVsemiconductor devices, extended researches have been carried out including fundamentals and applications of Langmuir-type adsorption/reaction process such as atomic-layer growth and etching. As to atomically controlled processing, by utilizing a low-temperature ultraclean reaction atmosphere, flash heating by Xe lamps, and low-energy ion irradiation by an ECR plasma, we have achieved atomic layer-by-layer growth of Si and Ge, atomic-layer nitridation of Si by NH_3 at 400ﾟC, atomic-layer carbonization of Si(100) by CH_4 at 500-600ﾟC, atomic-layer adsorption of SiH3CH3 on Si and Ge, atomic-layer doping of P on Si and Ge, fractional atomic-layer etching of a SiGe system, atomic-layer role-share etching of silicon nitride, etc. Adsorption and reaction process in low temperature selective deposition of W has been also investigated by alternate supply of WF6 and SiH_4. Each of these atomic-order processes has been described by Langmuir-type simple adsorption and reaction formalism, which contributes to establish a base of a high precision control of the process. As to device fabrication process, we have fabricated ultrasmall MOSFETs utilizing super-self-aligned ultrashallow junction formation in the source/drain region, and MOSFETs with a SiGe epitaxial layer as a channel. Also, we have developed each process such as selective epitaxy of SiGe and in-situ heavy doping with P and B, highly selective anisotropic etching of heavily doped polysilicon, reduction of source/drain resistance by selective growth of W, as well as a total ultrasmall device process by combination of these individual processes. These research results supply a fundamental key to ultrasmall device fabrication technology with group IVsemiconductors.