A Plague-Free Aluminum-Gold System on Silicon Integrated Circuits

A stable and reliable aluminum-gold system for inter-connections, contact pads, and bonded lead wires for silicon integrated circuits has been studied. The system is completely consistent with the fabrication technology, packaging, storage, and operational requirements of standard integrated circuits. It is based on an isolation of the aluminum interconnection metal from the gold contact metal by the bulk substrate material. The interconnections are vapor deposited aluminum, contact pads are gold vapor deposited on a chromium wetting agent, and the bonded lead wires are gold. The interconnections are separated from the contact pads by a barrier domain of bulk silicon substrate material which has been degenerately doped. The system is not subject to degradation due to the intermetallic formation which is common in conventional aluminum-gold systems. The electrical, mechanical, and metallurgical properties of this system are superior to those of the standard expanded contact configuration except for a 1.25 ohmincrease in resistance which arises from the diffused conduction tunnel.