US Patent 7993936 System and method for controlling an electrochemical etch process

By evaluating a status signal on the basis of a fault detection classification mechanism in an electrochemical etch tool, a corresponding failure status of the tool may be obtained for each single substrate, thereby significantly reducing the risk of significant yield loss compared to conventional strategies. The fault detection and classification mechanism may be advantageously applied to the electrochemical removal of underbump metallization layers during the formation of solder bump structures.