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Effects of Dwell Time and Current Density on Ion-Induced Deposition of Tungsten

Published online by Cambridge University Press:  25 February 2011

Khanh Q. Tran ,
Yuuichi Madokoro ,
Tohru Ishitani  and
Cary Y. Yang
Khanh Q. Tran
Affiliation:
Microelectronics Laboratory, Santa Clara University, Santa Clara, CA 95053
Yuuichi Madokoro
Affiliation:
Central Research Laboratory, Hitachi, Ltd., Kokubunji Tokyo 185, Japan
Tohru Ishitani
Affiliation:
Central Research Laboratory, Hitachi, Ltd., Kokubunji Tokyo 185, Japan
Cary Y. Yang
Affiliation:
Microelectronics Laboratory, Santa Clara University, Santa Clara, CA 95053
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Abstract

30-keV focused Ga+ ion beam was used for induced deposition of small-area tungsten thin films from W(CO)6 on Si and SiO2. Deposition yield, calculated assuming pure tungsten depositions, depends on dwell time (beam diameter/scan speed) and beam current density. High current density and/or long dwell time are known to cause low deposition yield because of the depletion of adsorbed gas molecules during ion beam irradiation. Based on a model taking this effect into account, numerical fitting was carried out. The reaction cross-section was estimated to be 1.4 × 10−14 cm2. For doses below 1017 ions/cm2, film resistivity decreases with increasing dose. This was confirmed for several dwell times. However, for doses above 1017 ions/cm2, film resistivity remains independent of dose. In this “high”-dose range, variation of beam current density has little effect on film resistivity. AES analyses revealed a consistency between film composition and resistivity. For a “high”-dose film with a resistivity of 190 μΩ-cm, the approximate tungsten content was 50 at%.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 181: Symposium B – Advanced Metallizations in Microelectronics , 1990 , 585
Copyright
Copyright © Materials Research Society 1990

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References

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