Aluminum-capped copper bond pads for ultrasonic heavy copper wire-bonding on power devices

Thick electroplated Cu bond pads have lately been demonstrated to enable heavy Cu wire-bonding but the Cu oxides necessitate an additional cleaning step after the die-attach. To avoid such cleaning, the use of a thin Al layer is tested for its passivating ability on Cu bond pads and its suitability for the bonding process. Results show a significant improvement of the oxidation resistance and bonding performance.