Development of an Electrochemical Deposition Solver

Electrochemical deposition is a common method used in the field of microelectronics to grow metallic coatings on an electrode. The deposition process occurs in an electrolyte bath where dissolved ions of the depositing material are suspended in an acid while a current is applied to the electrodes. An oxidation reaction occurs at the anode and a corresponding reduction reaction occurs at the cathode, where a metallic layer grows. An applied current drives the process and creates an electric potential field within the electrolyte that is coupled to changes in concentration of the ions in the electrolyte bath and any fluid motion that occurs to replenish the concentration at the cathode. During the PISO loop for the incompressible flow solver we include a second predictor-corrector loop to enforce convergence of an interface voltage between the electrolyte and the cathode. This is achieved in part to the finite area method that is used to calculate an electric potential on the cathode surface. Finite area fields are also used to keep track of the deposited metal on the cathode, the interface current density, and the converging interface voltage. This approach does not require the use of a level-set method or a deforming mesh. The growth of the metallic layer is small enough that it is not expected to impact the fluid motion. As the metallic layer grows the resistance on the wafer is increased, which results in a lower current density and a decreased rate of deposition. In this talk we will define how we implemented the finite area method in our solver and how we modified the equations for electric potential and concentration to be more strongly coupled.