| Co-Investigator(Kenkyū-buntansha) |
SAWADA Yasuji TOHOKU UNIVERSITY,RESEARCH INSTITUTE OF ELECTRICAL COMMUNICATION,PROFESSOR, 電気通信研究所, 教授 (80028133)
MUROTA Junichi TOHOKU UNIVERSITY,RESEARCH INSTITUTE OF ELECTRICAL COMMUNICATION,PROFESSOR, 電気通信研究所, 教授 (70182144)
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| Research Abstract |
The purpose of this study is to clarify the basic process of atomic layr etching of Si, ie., self-limited adsorption of reactant atoms on the Si surface and etching reaction of the surface induced by the low energy ion irradiation. In this fiscal year, as the last research year of this 2 year project, research has been extended from self-limited atomic-layr-etching of Si to that of Ge and to application of low energy ECR chlorine plasma to ultrasmall MOS gate fabrication.
Atomic layr etching of Si (100), (111), (110), and(211)has been investigated by alternated chlorine adsorption and low energy Ar^+ ion irradiation using an ultraclean ECR apparatus. It is found that the etch rate per cycle in saturation when chlorine radicals are supplied is twice as high as that when only molecules are supplied. Also it is expressed by a well-regulated fractional number of the atomic layr thickness for each substrate orientation. Moreover, the saturated etch rate is in a simple relation to the surface bond structure and the adsorption site of each substrate orientation. Not only on the molecular chlorine adsorbed surface but also on the chlorine radical adsorbed surface during atomic-layr-etching, XPS measurements showed the absence of Si^<2+> and Si^<3+>and the -1 atomic layr adsorption of chlorine. In these atomic-layr etching of Si, etching depth depends on the amount of the chlorine adsorption. In the case of Ge, etching characteristics showed dependence on the amount of the low energy Ar^+ ion irradiation. This remarkable result demonstrates difference of kinetic constant of adsorption and reaction. Also, highly selective directional gate etching of ultrasmall MOSFET's with a 0.1 micron feature size have been fabricated by low energy ECR chlorine plasmas.
The success of this project supplies a key to understand more deeply the atomic layr etching process and we summarized this project.
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