Dissolution Behavior of Metal Impurities and Improvement of Reclaimed Semiconductor Wafer Cleaning by Addition of Chelating Agent

As a wafer cleaning process, RCA (Radio Corporation of America) cleaning is mainly used. However, RCA cleaning has problems such as instability of bath life, re-adsorption of impurities and high-temperature cleaning. Herein, we tried to improve the purity of silicon wafers by using a chelating agent (oxalic acid) to solve these problems. Compounds produced by the reaction between the cleaning solution and each metal powder were identified by referring to the pourbaix diagram. All metals exhibited a particle size distribution of 10 μm or more before reaction, but a particle size distribution of 500 nm or less after reaction. In addition, it was confirmed that the metals before and after the reaction showed different absorbances. As a result of elemental analysis on the surface of the reclaimed silicon wafer cleaned through such a cleaning solution, it was confirmed that no secondary phase was detected other than Si.