Additial microstructural analysis on the samples examined in the paper `Are high resolution resistometric methods really useful for the early detection of electromigration damage?'

摘要

In a previous paper (A.Scorzoni, S.Franceschini, R.Balboni, M.Impronta, I. De Munari, and F. Fantini, Are high resolution resistometric methods really useful for the early detection of electromigraton damage? Microelectr. Reliab. 1997;37(10/11):1479-1428), we reported largely different electromigaration lifetimes and different high resoluion early resistance changes measured on two nominally identical lots of 4μm wide lines tested at moderately accelerted stress conditions. A microstructural analysis on unstressed samples was performed in order to detect the reason which induced these differences. The analysis confirmed a major defectivity of the lot with shorter lifetime: we detected the presence of TiAl_3 precipitates at the interface between the Al-Cu and the Ti-based metal barrier. This was not easily detectable by means of simple visual inspection. These additional findings confirm that a quick electricla detection of the metallization quality could be feasible by means of high resolution resistance measurements without the need of time-consuming direct examination of production lots.