Method to improve the reliability of gold to aluminum wire bonds with small pad openings

摘要

In method for manufacturing an integrated circuit improves the reliability of thermosonic bonds formed to attach a gold bond wire to an aluminum interconnect pad, where a pad opening in the integrated circuit is on the order of 60 microns. In the method, a reactive ion etch (RIE) passivation etch is used which does not include a, more corrosive sulfur hexa-fluoride to remove the SiO₂ passivation layer above the pad. Instead, the RIE uses argon as the carrier gas, carbon tetrafluoride (CF₄) and trifluoromethane (CHF₃) as active etchants, and oxygen (O₂) to reduce the residual halide contaminant in the aluminum pad. Further, a thin titanium layer is deposited beneath the aluminum pad layer to improve adhesion of the aluminum pad to underlying layers of the semiconductor integrated circuit. The aluminum pad layer is made very thin, or less than approximately 8000 , to limit Kirkendall voiding.