Abstract
In semiconductor devices the gold wire bonding to aluminium pads is a widely used bonding practice. The reliability of bond strength exerts a strong influence on that of IC or LSI.
Voids formed in gold-aluminium intermetallic compounds are known to degrade the long-term reliability of gold wire bonds to aluminium pads. In this reliability, the annealing envirenment has great influence on the behavior of this voiding as well as the intermetallic formation.
The influence of annealing condition for gold-aluminium bonds was investigated comparing with the encapsulated condition and decapped condition.
Great differences were found between two conditions. In the case that initial shear strength is high, shear strength was high even after annealling in 200C-1000hr for decapped devices. However, in the case of encapsulated condition shear strength was degraded after annealling in 200C-100hr.
In the case of encapsulated condition, intermetallic compounds was corroded by bromine included in resin. And this corroded compound degraded gold-aluminium bonding. On the other hand, in the case that initial shear strength is low, shear strength became low after annealling in 200C-100hr for both conditions.
In conclusion, shear strength was degraded after annealling in 200C-100hr for encapsulated condition, irrelevant to bonding conditions.
