Systematics of Silicide Formation by High Dose Miplantation of Transition Metals into Si
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SYSTEMATICS OF SILICIDE FORMATION BY HIGH DOSE MIPLANTATION OF TRANSITION METALS INTO Si F. Namavar,F. H. Sanchez', J. I. Budnick, A. H. Fasihuddinand H. C. Hayden, Department of Physics, The University of Connecticut, Storrs, CT 06268, U.S.A.
ABSTRACT We have systematically studied the formation of transition-metal thin films by high dose (up to 2 108 ions/cm ) implantation of Ti, V, Cr, Mn, Fe, Co, Ni and Nb at room temperature and 350'C into Si < 100>. For implantation at 350'C, our results, as obtained by Rutherford backscattering, X-ray diffractometry and Read Camera measurements, indicate that one can categorize these metals into two groups: 1.
a chromium group which includes V, Cr, Nb, Ti and Mn. Metals V, Cr and Nb form compounds VSi2 , CrSi2 . NbSi 2) with a hexagonal structure of the CrSi2 type whereas Ti and Mn both form compounds (TisSi 3, MnsSi3) with a hexagonal structure of the MnSSi2 type.
2.
an iron group which includes Fe, Co and Ni. These metals form compounds (FeSi, CoSi, NiSi) with a cubic structure of the FeSi type.
In this paper the experimental results for Cr and Fe implantation at room temperature and 350'C will be discussed.
INTRODUCTION During the past several years there has been growing interest [1,21 in the formation of transition-metal thin films by means of ion beam mixing techniques. Although there has been a renewed interest in the formation of Si compounds by direct high dose implantation, these works have mainly concentrated on the formation of buried SiO2 131and Si 3N4 [4]. Only a few studies 15 - 81have been carried out on the formation of silicides by high dose implantation of transition-metals. During the past few years we have carried out systematic studies of silicide formation by high dose implantation of transition metals such as Ti, V, Cr, Mn, Fe, Ni, Co, etc. The aim of these studies was to understand the mechanism involved in silicide formation by implantation and to determine the phase formation sequence of silici -" thin films and their dependence on thermodynamics and kinetics. We also have investigated buried silicide layers formed by implantation 181.Discussion in the present paper is limited to the results of implantation of Cr and Fe into Si. Detail description of these works as well as effect of annealing from 300 to 1000°C on silicide formed by implantation will be given elsewhere 19].
EXPERIMENTAL PROCEDURE Summary of our experimental procedures and facilities has been given in earlier papers 16,101; however, we should add that during implantation at 350°C the sample holder was surrounded by a LN2 cold trap and warmed up by a heater. The temperature of samples during implantation was monitored and stabilized during implantation. Our samples were free from contamination resulting from impurity gettering 1 I I from the vacuum system.
EXPERIMENTAL RESULTS Cr implanted Si systems. Cr under well-defined conditions was implanted into Si < 100 > at both room and 350°C temperatures. Implantationat Room Temperature. Fig. 1 shows the RBS spectra of Cr implanted
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