This Small Business Innovation Research (SBIR) Phase II project will test a novel sensor for real-time detection of trace impurities important in micoelectronics manufacturing. Gas feedstock quality is an important measurement for any process control strategy because contamination at the part-per-billion (ppb) level may limit product yield. This project's technique, called wavelength modulated photo-acoustic spectroscopy, has the potential to achieve these detection levels at a significantly lower cost than is possible with current technology. This technology is compatible with both corrosive and non-corrosive gases. The Phase II will construct and field test a prototype trace moisture sensor that is expected to achieve 10-ppb detection limits in corrosive gases such as hydrogen chloride and ammonia.<br/><br/>Potential commercial applications are expected in on-line removal of trace impurities important in micoelectronics manufacturing.