Effects of Various Passivation Dielectrics and Via Reservoir Lengths on Stress and Electromigration Reliability of Metal Interconnects

Abstract

ABSTRACTReservoir length dependencies of electromigration lifetime in multilevel interconnect were compared for two passivation dielectrics, that is, FOX (Flowable Oxide) and HDP FSG (High Density Plasma Fluorinated Silicate Glass). The higher electromigration resistance of interconnects passivated by FOX can be best explained by their lower stress and vacancy concentration levels than the case for FSG. It was also proposed that lower levels of stress and vacancy concentration in the longer reservoir could partially contribute to the better electromigration reliability of interconnect with the longer reservoir.