| 摘要 |
<p>The present invention relates to the field of wet chemical treatment of silicon substrates. The invention particularly relates to a method for the determination of the concentration of nitric acid in aqueous process solutions as being used for the treatment of substrates such as those made from silicon. The method is based on the determination of nitrate by means of UV spectroscopy/photometry with the aid of eliminating agents which effectively remove disturbing absorptions caused by other substances. Therein, the concentration of nitrate corresponds to that of nitric acid. According to the invention, a robust method is proposed by means of which the content of nitric acid in acid mixtures can be determined very precisely, and in fact likewise in fresh as well as in acid mixtures that have been used according to their intended purpose.</p> |
