| Research Abstract |
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.
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