Determination of Metal Contaminants Using Automated In-Situ Metrology in Semiconductor Cleaning Process

This paper reports development of an in-situ metrology tool for monitoring metal contaminants existing in the semiconductor wafer cleaning process. Simultaneous detection of aluminum and transition metals at different wavelengths without significant interferences was made possible spectroscopically, using a mixture of 4-2- (pyridylazo) resorcinol and eriochrome cyanine red chelating reagents. This novel technology and apparatus designed for the fully automated in-situ metrology system enabled quantitative analysis of metal contaminants, even at sub-ppb concentrations. The metal monitoring technology is expected to be highly useful not only in semiconductor fabrication but also in several other industrial and academic fields.