Annealing Characteristics of Al-Light-Rare-Earth Alloy Thin Films for Microelectronic Conductor Lines

The addition of La and Pr to Al thin films markedly decreases the grain size of the Al matrix and largely suppresses growth of thermal defects of hillocks and whiskers at high temperatures (350°C - 450°C). A large number of fine metallic compounds of AI11RE3 and/or AI3RE (RE = La and Pr) were segregated in an Al matrix, mostly at grain boundaries, after annealing at 350°C. The resistivities of the films after annealing at the above temperatures show very low values of less than 6 μΩcm, without the salient formation of hillocks or whiskers on the film surfaces.