Enhancement of semiconductor wafer cleaning by chelating agent addition

To realize environmental and cost benefits it is desirable to reduce the RC A cleaning sequence from its historical SC1 + SC2 combination, in which the particle-removing SCI solution deposits certain metals, necessitating the metal-removing SC2. One approach is to add a chelating agent to the SC1. Ex tensive testing of SCI solutions with addition of the complexing agent 1,2- cyclohexanediaminetetraacetic acid (CDTA) were performed. CDTA was shown to be more stable than other complexing agents in SCI solutions, facilitating significant bath life extension. Further, SCI solutions with CDTA were sho wn to be capable of removing large quantities of metals from contaminated w afers, comparable to SC2, and preventing deposition of metals. An exception is aluminum, which can deposit from SCI even with large amounts of added C DTA, but which can be removed by a subsequent dilute (1000:1) H2O:HCl step. (C) 2001 The Electrochemical Society.