Development of copper wire bonding application technology

Continuous forming of oxidation-free, stable, fully spherical copper balls has been realized by blowing reduction gas onto the copper wire during copper-ball formation (sparking). Chip damage resulting from hard copper wire, including underpad crack and silicon cratering, have been major technical hurdles to copper wire bonding. These problems have been overcome by introducing the double-load wire-bonding technology. Unlike conventional wire-bonding the double-load technology can minimize chip damage from wire-bonding stress because the bonding load is reduced during ultrasonic power oscillation. The double-load technology has made copper wire bonding applicable to MOS LSI devices