Gap fill process stability monitoring of an electroplating process using a potential-controlled exit step

摘要

Various embodiments herein relate to methods and apparatus for electroplating metal on a substrate. In many cases, an electroplating process may be monitored to ensure that it is operating within a pre-defined processing window. This monitoring may involve application of a controlled potential between the substrate and a reference electrode after the electroplating process is substantially complete (e.g., after recessed features on the substrate are substantially filled). The current delivered to the substrate during application of the controlled potential is monitored, and a peak current is determined. This peak current, often referred to herein as the potential-controlled exit peak current, can be compared against an expected range to determine whether the electroplating process is operating as desired.