Influence of surface tension on cavitation noise spectra and particle removal efficiency in high frequency ultrasound fields

Abstract

Influence of surface tension on cavitation noise spectra and particle removal efficiency in high frequency ultrasound fields, Journal of Applied Physics, 112(11). Archived versionFinal publisher's version / pdf Influence of surface tension on cavitation noise spectra and particle removal efficiency in high frequency ultrasound fields Physical cleaning methods are applied in the semiconductor industry and have become increasingly challenging due to the continued scaling of semiconductors device elements. Cavitation and acoustic phenomena are known to play a fundamental role in megasonic cleaning. Hence, a better understanding of cavitation phenomena in multi-bubble systems is crucial. Here, a study on the effects of lower bulk surface tension and different O 2 concentrations on the bubble activity in the megahertz range is presented. A lower bulk surface tension (45 mN/m) with respect to ultra pure water (72 mN/m) is obtained by adding a non-ionic surface-active agent (Triton X-100). After a thorough surfactant characterization, a Triton X-100-containing cleaning solution is investigated under pulsed and continuous acoustic fields, for different acoustic amplitudes and gas concentrations. It is demonstrated that cavitation activity, measured by means of ultraharmonic cavitation noise, is enhanced in presence of a lower surface tension, under continuous acoustic fields. In addition, cavitation measurements performed under pulsed fields reveal the existence of optimal pulse-off times, for which a maximum of activity is observed. These optimal pulse-off time values are linked to the bubble dissolution theoretical times and experimentally verified. To end, cavitation noise measurements are correlated to cleaning performance in megasonic fields by means of particle removal and damage tests on patterned wafers. A clear increase in particle removal efficiency of 78 nm SiO 2 particles is obtained when Triton X-100 is employed, at the optimized process conditions. In addition, the number of defects due to cavitation bubbles is significantly reduced for lower surface tension, at particle removal efficiencies <60%. The results here reported constitute a different approach towards more efficient megasonic cleaning processes.

Detergent Dissolution Intensification via Energy-Efficient Hydrodynamic Cavitation Reactors

“…These results suggest that increasing the initial concentration of detergent leads to a decrease in the inception pressure, the reason for which can be the change in the water tensile strength after mixing with detergent. The obtained results are consistent with previous findings, which show that surfactants (the primary component in detergents) facilitate bubble growth and in consequence inception by influencing surface tension, interfacial resistance to mass transfer, and surface rheological properties. , Thus, it can be inferred that the increase in the liquid detergent-to-water ratio leads to cavitation inception in smaller upstream pressures.…”

Enzymatic protection and biocompatibility screening of enzyme-loaded polymeric nanoparticles for neurotherapeutic applications

“…To best gain insight into potential mechanisms of DCM-dependent toxicity, we compared the characteristics of DCM, EtAc, and TCM. Solvents with higher vapor pressure and lower surface tension undergo vapor bubble formation and subsequent cavitation at less extreme pressures [41,42]. Because DCM has the highest vapor pressure of the three solvents as calculated from the Antoine equation (DCM: 353 mmHg, TCM 158 mmHg, EtAc 74 mmHg at 20°C) [43], we speculate that under the nanoparticle formulation parameters used in our experiments, the sonication energy input was mild enough that cavitation only occurred with DCM as the organic solvent.…”

Influence of Surface Tension on Dynamic Characteristics of Single Bubble in Free-Field Exposed to Ultrasound

“…Camerotto et al [ 17 ] conducted a study on the effects of lower bulk surface tension on bubble activity and surface cleaning performance. It was demonstrated that cavitation activity, measured by means of ultra-harmonic cavitation noise, is enhanced in the presence of lower surface tension.…”

“…The results showed that the liquid surface tension not only affected the bubble’s stability in the ultrasonic field but also obviously influenced the characteristics of the bubble’s typical motions near a rigid wall, such as moving, collapse, and rebound. In addition, more researchers were more willing to analyze the influence of liquid surface tension with various numerical methods [ 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 ]. Among these methods, the R–P equation (Rayleigh–Plesset equation) is regarded as the most classic one [ 28 ].…”