A New Potentiometric Sensor for the Detection of Trace Metallic Contaminants in Hydrofluoric Acid

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Detection of ultratrace levels of metallic ion impurities in hydrofluoric acid solutions was demonstrated using a silicon‐based sensing electrode. The sensor's operation principle is based on direct measurements of the silicon open‐circuit potential shift generated by the charge‐transfer reaction between metallic ions and the silicon‐based sensing surface. For instance, the silicon‐based sensor is capable of detecting parts per‐trillion to parts‐per billion level of ions in HF solutions with a detection sensitivity of ca. +150 mV shift per decade change of . The new sensor can have practical applications in the on‐line monitoring of microelectronic chemical processing.