Quantification of Silicon Wafer Cleaning Using Secondary Ion Mass Spectroscopy

The basic surface cleanliness requirements for Si-based semiconductor technology have become an increasingly more difficult analytical problem as the density of active elements on integrated circuits has increased. No longer is a relative “sea” of Si present to soak up and disperse contaminants left from one processing step so they will not affect subsequent steps. The basic sensitivity of Auger electron spectroscopy (AES) and electron spectroscopy for chemical analysis (ESCA) has been stretched to the limit for a number of elements [1] and therefore a study of the application of SIMS to this problem was undertaken. This study concentrates on the analysis of the s contaminants in the native oxide left on Si wafers after most cleaning processes and the quantitation of the impurity elements found in this layer.