A non-destructive, fast evaluation of PVD diffusion barriers deposited on porous low-k dielectrics

Abstract Non-destructive and fast evaluation of thin diffusion barriers deposited on top of porous low-k dielectrics by spectroscopic ellipsometry is demonstrated. Studying Physical Vapor Deposited (PVD) CoTa and CoW alloys has shown that 3 nm and 5 nm thick barriers still have holes sufficient for penetration of neutral molecules. This study also detected damage to OSG low-k films which occurs during barrier deposition. VUV light emitted by Ar plasma which is used for metal target sputtering is likely to have caused this damage. For this reason, low-k films were placed under the barriers in order to adsorb moisture during air storage. W atoms also penetrated pores of low-k film during the deposition phase.