Investigation of ion beam mixing effects in Ta/Pd bilayers deposited on Si

Abstract

This paper presents a study of the effects of As+ ion irradiation and vacuum thermal treatments on Ta/Pd bilayers on silicon. The layers were deposited by DC sputtering to the thickness of 60 nm (Pd) and 45 nm (Ta) on (111)Si wafers. The Ta/Pd/Si structures were then implanted with 300, 400 and 500 keV As+ ions at room temperature (RT), to the doses from 0.5-1.10(16) ions cm(-2). Thermal treatments of samples were performed in vacuum at 900 degrees C, for 10 min. Characterizations were performed by Rutherford backscattering spectroscopy and X-ray diffraction. It was found that intermixing of the components at Ta/Pd and Pd/Si interfaces depends on the value of damage energy F-D deposited by the incident ions at the interfaces. Ion bombardment at room temperature induces the formation of Pd2Si phase with polycrystalline structure. Post-implantation annealing at 900 degrees C made possible the growth of PdSi silicide. Then, the reaction of Ta with Si is enhanced by rapid silicon diffusion through already formed PdSi phase. Consequently, the formation of TaSi2 and Ta3Si silicides at the Ta/PdSi interface occurred. (C) 1998 Elsevier Science S.A.