Reactions and orientation effects of the Fe/Pd/Cu/Si, Fe/Ag/Pd/Cu/Si, Fe/Au/Pd/Cu/Si, and Fe/Pt/Pd/Cu/Si structures using (100) and (111) Si

Abstract

(100)- and (110)-oriented Fe films, grown on Pd/Cu/Si, Ag/Pd/Cu/Si, Au/Pd/Cu/Si, and Pt/Pd/Cu/Si using (100) and (111) Si, respectively, have been heated to 600°C, and the reactions studied. The (100) Fe films remain little changed both structurally and magnetically, after an anneal of 30 min between 300 and 400°C in an ambient of N2-H2 (9:1). The saturation magnetization shows little change at 400°C, while the coercivity increases at this temperature. Above 400°C, the Fe films degrade depending on the structures grown. For the Fe/Pd/Cu/Si and Fe/Pt/Pd/Cu/Si structures, both the magnetic and structural characteristics of Fe remain partially intact at 600°C. In both cases, the Pt and Pd layers have been consumed for the silicide formation above 400°C. For the Fe/Ag/Pd/Cu/Si structure, Fe rapidly degrades at 500°C, with Ag being little changed till 600°C. For the Fe/Au/Pd/Cu/Si structure, the formation of the bulk Au-Si eutectic melt at 363°C completely destroys the Fe layer above 400°C. In comparison, a lower thermal stability is observed for the (110) Fe layers grown on (111) metal seeds using (111) Si, with reduced saturation magnetizations at 400°C. A larger diffusion of Pd, Ag, Au, and Pt into the (110) Fe layers is also observed than those deposited on (100) Si. The mechanisms involved are discussed and are related to the different thermal stabilities observed.