Cobalt Electrofill for Future Generations of Contacts and Interconnects

In traditional copper damascene interconnect electroplating baths, three organic additives (accelerator, suppressor, leveler) are used to produce void-free superconformal fill. Here, a different mechanism for electroplating void-free cobalt interconnects is described. Superconformal void-free cobalt fill is generated using a sacrificial oxidant (H⁺) and the addition of a single suppressor-type additive. A differential plating rate on the field and feature bottom can be obtained through process tuning involving waveform, mass transport conditions, pH, and suppressor concentration.