Metrology for High Selective Silicon Nitride Etch

This paper demonstrates a variety of metrology methods for high selective silicon nitride etch in different process baths. Capability of measuring full matrix components is also presented. For the measurement of H3PO4 and H2O, both NIR spectroscopy and conductivity methods work well. Si measurement in the etchant that contains an organo-silicon compound requires a new reagent development in comparison with the original reagent method developed for regular process contains inorganic Si only.