Ultrasonic Cavitation Probe for Monitoring and Testing Engineered Surfaces

This Small Busuness Innovation Research (SBIR) project will develop an initial prototype design for a cavitation probe that uses the property of a collapsing cavitation bubble to produce visible photons (sonoluminescence) has been designed and constructed. These light emissions can be easily detected within a small, finite volume and thus this probe provides a direct means of measuring the cavitation density (activity/per unit volume) within a cavitating fluid and the delivery of ultrasonic energy at an engineered surface. As a result, ultrasonic methods treating a surface can be directly monitored and controlled in real-time, leading to the ability to improve and predict the performance of the resulting structure. For example, since cavitation is thought to be the principal mechanism that leads to particle removal from silicon wafers during an ultrasonic/megasonic cleaning operation, it is likely that a strong correlation exists between cavitation probe output and cleaning effectiveness. Thus, this probe provides the potential for constructing a real-time monitor of ultrasonic/megasonic cleaner efficiency and effectiveness. In addition, because the entire three-dimensional cavitation field can be measured with this probe, it can also serve as a useful tool in ultrasonic/megasonic cleaner design. A real-time cavitation-density measuring device would have great utility in the semiconductor cleaning industry and thus this probe provides considerable promise for commercial development.