Damascene process induced charging damage phenomenon

Performance degradation of MOSFETs due to plasma charging damage in a damascene interconnect process was evaluated in contrast to the conventional interconnect process which utilizes reactive ion etching (RIE) for metal patterning. Greater MOSFET performance degradation was observed in the damascene interconnect process than that in the metal RIE based interconnect process, notwithstanding the process where devices were directly exposed to plasma was reduced. It is considered that the degradation is due to the discharge current of charges which are charged up in the interconnect trench during the trench RIE process. A two step etching process using an etch stopper on metal was confirmed to reduce the charging damage