Planarized metallization by the blanket PACVD aluminum for ULSI

A thin layer of copper was deposited on top of the plasma assisted chemical vapor deposited aluminum and the electromigration phenomenon was investigated. It turned out that electromigration resistance of the aluminum film deposited by plasma assisted chemical vapor deposition (PACVD), was better than the sputtered aluminum film. The top copper layer also improved electromigration resistance of PACVD aluminum after the annealing (450 degrees C, 1 hr). According to the microstructural analysis, it has been found that PACVD aluminum shows a large grain size, uniform distribution of grain size and (111) preferred orientation, which are responsible for excellent electsomigration resistance of PACVD aluminum.