2CO.16.6: OPTICAL SPECTROSCOPY OF CHELATED TRACE METALS FOR WET CLEANING PROCESS CONTROL AND OPTIMIZATION

摘要

UV-visible spectroscopy is a technique that readily allows one to determine chemical concentrations ofa wide variety of substances over a wide range of conditions. Iron, cobalt, nickel, titanium and copper are importantmetals that when present on a silicon wafer surface adversely influence the efficiency of resulting PV devices.However, many of these surface ions can be effectively removed during wafer cleaning by the addition of acomplexing or chelating agent (such as SX-E?). Since many of the ion-chelate molecular complexes exhibit opticalabsorption and/or fluorescence in the easily-accessible UV-visible spectroscopy range, they are suitable for chemicalanalysis by spectroscopic techniques. In this paper, we explore the spectroscopy of several of these metal ioncomplexes, as well as their potential for chemical analysis and process control, e.g. for endpoint detection,measurement of cleaning bath lifetimes, and as a tool to optimize cleaning sequences.