Copper drift in low dielectric constant insulator films caused by O2+ primary ion beam

Copper depth profiling in low-k material methylsilsesquioxane (MSQ) was investigated. Cu was implanted into MSQ or thermally grown SiO2 and depth profiling was carried out with O2+ primary ions, and charge neutralization with electron flooding using a quadrupole SIMS. The obtained profile was deeper and broader than the theoretically predicted ones and Cu drifting during the depth profiling was implied. Though the primary ion energy was lowered to 1 keV, it was not enough to suppress the redistribution. Though MSQ showed shrinking by electron irradiation, this did not seem to be the major origin of the Cu redistribution.