This Small Business Innovation Research (SBIR)Phase I project proposes to support the development of a real-time, insitu sensor for the monitoring and control of next-generation semiconductor etch tools. The sensor is based on ultrasensitive diode-laser absorption techniques for measurements of important native etch products (HF, DF, CO). This novel sensor system will measure concentrations of native etch products insitu with high sensitivity, accuracy, speed and specificity, eliminating the need for auxiliary etch stop<br/>layers. These auxiliary etch stop layers, which are currently used for control of the etch process, increase<br/>layer capacitance, and hence reduce operating speed of the devices in production.<br/><br/>This sensor system has direct commercial impact on the next-generation etch tools and their<br/>process capabilities. The real-time control afforded by this sensor system will likely become an industry<br/>standard and become a critical subcomponent of the semiconductor etch tool market. Application to<br/>other plasma-based process tools is a natural extension of this technology, as well as extension to other<br/>application areas including industrial process control, vehicle engine testing, and atmospheric and<br/>environmental monitoring.