Hexafluorosilicate in etching baths

Determination of silicate and hexafluorosilicate (calculated) in an etching bath using anion chromatography with conductivity detection after chemical suppression (see AN S-284) and subsequent UV/VIS detection with post-column reaction. Hexafluorosilicate is hydrolyzed into fluoride and silicate. The measured silicate concentration is used for the calculation of the SiF62- concentration.