Reliability characterization of organic ultra low k film using ramp voltage breakdown

Abstract

This paper deals with the leakage and dielectric breakdown of an organic nanoporous ultra low k (ULK) film when it is exposed to different plasma conditions. The ULK film was exposed to different plasma conditions before depositing hardmask for further integration. This was to simulate sidewall damage caused by plasma etch processes. Blanket ULK wafers were also subjected to same plasma treatments and MS type capacitors were fabricated. Voltage ramp results of integrated and MIS structures on blanket films were compared. Subjecting ULK to different oxidizing and reducing plasma conditions resulted in high leakage and low dielectric breakdown strength indicating that the dielectric reliability is significantly decided by weakest ULK/hardmask interface. Use of hardmask during integration prevents ULK surface plasma damage, but the damage to trench sidewalls cannot be prevented. However, sidewall damage did not contribute to dielectric leakage as is exemplified by the promising results from untreated wafers that show low leakage until breakdown.