Control of sonoluminescence signal in deionized water using carbon dioxide

Megasonic cleaning is routinely employed in semiconductor industry for cleaning of wafers. However, the method also results in damage to wafer features and such damage has been proposed to arise from transient, imploding cavities formed during megasonic processing. Transient cavitation is associated with the release of light, a phenomenon called sonoluminescence (SL) and the extent of damage has been shown to correlate with the intensity of SL. Control of sonoluminescence may therefore allow control of damage during megasonic processing of wafers. In this study, the ability of carbon dioxide to quench sonoluminescence generation in deionized water exposed to megasonic field of varying power density and duty cycle has been systematically investigated. It has been found that CO"2 is not only incapable but also a potent inhibitor of sonoluminescence, providing a potential means for selective alleviation of the violent effects of transient cavitation in process fluids. A novel chemical method has been established for in situ release of CO"2 from NH"4HCO"3 through a pH induced shift in the carbonic acid equilibria in deionized water. Using this method, a precisely controlled, progressive decrease in SL of air saturated deionized water through addition of NH"4HCO"3 has been demonstrated. It has been determined that 130ppm of released CO"2 is sufficient for complete inhibition of sonoluminescence generated in air saturated deionized water.

[1]  N. Dezhkunov.  Multibubble sonoluminescence intensity dependence on liquid temperature at different ultrasound intensities. , 2002, Ultrasonics sonochemistry.

[2]  H. S. Fogler,et al.  Second-order sonochemical phenomena--extensions of previous work and applications in industrial processing , 1974 .

[3]  D. Smailus,et al.  Cavitation science: Is there a simple theory of sonoluminescence? , 2001, Nature.

[4]  W. M. Haynes.  CRC Handbook of Chemistry and Physics , 1990 .

[5]  Seth Putterman,et al.  Defining the unknowns of sonoluminescence , 1997 .

[6]  T. Leighton.  The Acoustic Bubble , 1994 .

[7]  M. Ashokkumar,et al.  Single bubble sonoluminescence--a chemist's overview. , 2004, Chemphyschem : a European journal of chemical physics and physical chemistry.

[8]  Abdelkrim Khelif,et al.  Streaming and removal forces due to second-order sound field during megasonic cleaning of silicon wafers , 2000 .

[9]  P. Deymier,et al.  Megasonic cleaning of wafers in electrolyte solutions: Possible role of electro-acoustic and cavitation effects , 2009 .

[10]  Guy Vereecke,et al.  Evaluation of Megasonic Cleaning for Sub-90nm Technologies , 2005 .

[11]  Ahmed Busnaina,et al.  An Experimental Study of Megasonic Cleaning of Silicon Wafers , 1995 .

[12]  E. N. Harvey.  Sonoluminescence and Sonic Chemiluminescence , 1939 .

[13]  A. Busnaina,et al.  ROLES OF CAVITATION AND ACOUSTIC STREAMING IN MEGASONIC CLEANING , 1999 .

[14]  J. Vasseur,et al.  Second-order sound field during megasonic cleaning of patterned silicon wafers: Application to ridges and trenches , 2001 .

[15]  K. Negishi,et al.  Experimental Studies on Sonoluminescence and Ultrasonic Cavitation , 1961 .

[16]  A. Busnaina,et al.  REMOVAL OF SILICA PARTICLES FROM SILICON SUBSTRATES USING MEGASONIC CLEANING , 1997 .

[17]  F. R. Young.  Sonoluminescence from water containing dissolved gases , 1976 .

[18]  B. Djafari-Rouhani,et al.  Theoretical calculation of the acoustic force on a patterned silicon wafer during megasonic cleaning , 2000 .

[19]  K. Suslick,et al.  Temperature of Multibubble Sonoluminescence in Water , 1999 .

[20]  P. Deymier,et al.  Megasonic Metrology for Enhanced Process Development , 2009 .

[21]  S. Daniels,et al.  Sonoluminescence in water and agar gels during irradiation with 0.75 MHz continuous-wave ultrasound. , 1991, Ultrasound in medicine & biology.

[22]  S. Putterman,et al.  Effect of Noble Gas Doping in Single-Bubble Sonoluminescence , 1994, Science.

[23]  T G Leighton,et al.  Acoustic emission and sonoluminescence due to cavitation at the beam focus of an electrohydraulic shock wave lithotripter. , 1992, Ultrasound in medicine & biology.