Diffusivity and Solubility of Si in the Al Metallization of Integrated Circuits

Si was diffused along the evaporated Al layer of an integrated-circuit structure at temperatures between 360 and 560 °C, and the resulting concentration profile analyzed by electron microprobe. The Si solubility was found to agree with literature values for Si in wrought Al. The Si diffusivity was found to be substantially enhanced, however, probably due to a high density of imperfections in the evaporated Al film. Our measured diffusivities indicate an activation energy EA ≃ 0. 8 eV, about 40% less than the value for Si in wrought Al.