| 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 |
In this study, we have aimed at establishing the atomic layr etching technology of Si with a self-limited adsorption and reaction mechanism, and extended the research onto the Ge atomic layr etching as well as application of the low energy ECR chlorine plasma to the gate pattern fabrication in ultrasmall MOS devices.
In self-limited atomic-layr-etching of Si, the etch rate per cycle in saturation for each crystal orientation has been found to agree well with the well-regulated fractional number of the atomic layr thickness, and the number when chlorine radicals are supplied is twice as high as that when only molecules are supplied. Moreover, the each rate in saturation is expressed by a simple relation consisting of the surface bond structure and the adsorption site of each orientation. In such the results, the Si etching amount depends on the amount of the chlorine adsorption. On the contrary, in the case of Ge, under the condition of saturated chlorine adsorption, it has been found that the etch rate per cycle at the low Ar^+ ion irradiation is 1/4 atomic layr thickness, and increases with the Ar^+ ion irradiation and saturates to the single atomic layr thickness. Furthermore, at the high Ar^+ ion irradiation, the etching characteristics have been expressed by an exponentially approaching equation which is based on a simple equi-probability Ar^+ ion induced reaction. From the measured energy dependence of the incident Ar^+ ion flux, atomic layr etching of Ge has been found to be dominated by Ar^+ ions with energy higher than -13eV.Also, highly selective directional gate etching for ultrasmall MOSFET's with a sub-0.1 micron feature size have been achieved by low energy ECR chlorine plasmas.
Atomic layr etching can be considered as a final-selective-process, which is sensitive to the presence or the absence of adsorbed atoms. The success of this project supplies a key to the basic technology for ultrasmall device fabrication on group IV semiconductors.
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