Characterization of interfacial reactions between ionized metal plasma deposited Al-0.5 wt.% Cu and Ti on SiO₂

It was reported that the reaction between Al and Ti takes place and Al₃Ti compound is formed during the annealing at 500 °C. Annealing at higher temperatures, such as 550 and 600 °C, the Al₃Ti compound transforms to Al₅Ti₂. It is believed that the Al₅Ti₂ is thermodynamically stable comparing with Al₃Ti. In the present research, the interfacial reactions in Al-0.5 wt.% Cu/Ti/SiO₂/Si structure have been investigated in the samples prepared by ionized metal plasma (IMP) and then annealed at various temperatures from 200 to 600 °C for 30 min in Argon ambient. The results obtained by Rutherford backscattering spectroscopy and transmission electron microscopy show that there is a Ti layer (52 nm in thickness) between Al₅Ti₂ and SiO₂ and there is no formation of the ternary compound - Al_xTi_ySi_z, which is detrimental in the contact metallization layer. It indicates that the Ti layer deposited by IMP technique acts as a barrier to retard the reaction between Al₅Ti₂ and SiO₂ and consequentially protect the contact metallization layer.