Electrochemical deposition system including optical probes

An electrochemical deposition system comprising:

• an electrochemical deposition chamber including an electrolyte for electrochemical deposition;
• a substrate holder configured to hold a substrate and including a first cathode that is electrically connected to the substrate;
• a first actuator configured to adjust a vertical position of the substrate holder within the electrochemical deposition chamber;
• an anode that is submerged in the electrolyte;
• a second cathode that is arranged between the first cathode and the anode;
• a first optical probe configured to measure a first reflectivity of the substrate at a first distance from a center of the substrate while the substrate is submerged within the electrolyte during the electrochemical deposition;
• a second actuator configured to, while the substrate is submerged within the electrolyte, move the first optical probe from the first distance from the center of the substrate to a second distance from the center of the substrate that is different than the first distance;
• and
• a controller is configured to, during the electrochemical deposition, based on a first value of the first reflectivity measured when the first optical probe is the first distance from the center of the substrate and a second value of the first reflectivity measured when the first optical probe is the second distance from the center of the substrate, selectively adjust the at least one of (i) the power applied to the first cathode, (ii) the power applied to the second cathode, (iii) the power applied to the anode, and (iv) the vertical position of the substrate holder.