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

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. [Display omitted] •The paper reports a scalable application of ellipsometry for evaluation of critical properties of double thin diffusion films.•Present evaluation (TEM, TOF SIMS etc) is complicated, expensive and destructive.•Ellipsometry can provide basic important information about the barrier properties by non-destructive way very fast.•It makes this approach very efficient during the screening of new barrier materials and deposition conditions.