Effects of plasma/RTA Pretreatment on Cu Electroplating

摘要

In ULSI fabrication community, copper is now widely accepted as a new interconnect material to replace aluminum and its alloys due to its lower resistivity and higher electromigration resistance. In this study Cu seed layers deposited by magnetron sputtering onto a tantalum nitride barrier layer were given plasma H_2 and rapid thermal annealing (RTA) treatment for Cu nucleation enhancement prior to Cu electroplating. The combined effects of plasma H_2 pretreatment and rapid thermal annealing pretreatment of the Cu seed layer have been investigated on the resistivity, grain size and surface roughness of the electroplated copper films. The optimum pretreatment conditions for the Cu seed layer to obtain desirable surface roughness, grain size and resistivity of electroplated copper films were found to be the rf-power of 100 W and the exposure time of 10 min followed by rapid thermal annealing at 350 deg C. the mechanism through which Cu nucleation in electroplating is enhanced by plasma H_2/RTA has also been discussed.