Copyright 2011 Elsevier Inc. All rights reserved. Chapter 2 R. Nagarajan, S. Awad and K.R. Gopi.

Copyright 2011 Elsevier Inc. All rights reserved.

Chapter 2

R. Nagarajan, S. Awad and K.R. Gopi


FIGURE 2.1 Finite element simulation of propagation of megasonic waves in a tank [12]


FIGURE 2.2 Micro-streaming in a megasonic field [15]


FIGURE 2.3 Cross-sectional diagrams of (a) ultrasonic and (b) megasonic cleaners [18]


FIGURE 2.4 Ultrasonic cavitations and cleaning


FIGURE 2.5 Growth and collapse (implosion) of a cavitation bubble


FIGURE 2.6 Cavitation strength as a function of frequency


FIGURE 2.7 Cavitation abundance varies with frequency


FIGURE 2.8 Change in boundary layer thickness (relative to contaminant size) from ultrasonic to megasonic regime


FIGURE 2.9 The relationship between frequency and boundary layer thickness for room temperature water (theoretical simulation)


FIGURE 2.10 Effect of acoustic field parameters on streaming velocity [23]


FIGURE 2.11 Moment ratio model for particle removal from a surface. MR is the removal moment; MA is the adhesion resisting moment; Fdrag is the drag force; FAdhesion is the adhesion force; Felec double layer is the electric double layer

force; R is the particle radius; a is the contact radius between the deformed particle and the surface [23]


FIGURE 2.12 Experimental and theoretical particle removal efficiencies. Si-cap refers to a 4 nm silicon capping layer on the wafer [23]


FIGURE 2.13 Fluid motion generated by a sound field [24]


FIGURE 2.14 Removal and adhesion forces on a spherical particle [25]


FIGURE 2.15 Variation of streaming velocity with frequency


FIGURE 2.16 Optical principle of the liquid particle counter


FIGURE 2.17 Schematic diagram of a nephelometer


FIGURE 2.18 Cavitation meter


FIGURE 2.19 Cavitation intensity as a function of frequency and position within the cleaning tank


FIGURE 2.20 Mean cavitation intensity as a function of frequency (192-960 kHz)


FIGURE 2.21 Influence of dissolved oxygen on the particle removal efficiency (PRE) of 34-nm SiO2 particles [30]


FIGURE 2.22 Particle removal efficiency for 78- and 34-nm SiO2 particles in aerated deionized (DI) water and ammonia/peroxide mixture (APM) solutions (a) with megasonic agitation and (b) without megasonic agitation [37]


FIGURE 2.23 Traditional non-sweeping megasonic power distribution in a cleaning vessel


FIGURE 2.24 Sweep megasonic power distribution in a cleaning vessel


FIGURE 2.25 470 kHz tank with sweeping (courtesy of Crest Ultrasonics Corporation, USA)


FIGURE 2.26 Cavitation intensities in center and corners of sweeping megasonics (470 kHz from MSI, Inc., USA) and traditional megasonics (430 kHz)


FIGURE 2.27 Erodibility comparison at center of tank (based on turbidity measurement on extract solution)


FIGURE 2.28 Cleanability comparison at the center of the tank based on turbidity measurement of the extract solution


FIGURE 2.29 Mean size of surface residual particles after multiple cleaning stages


FIGURE 2.30 Comparison of cleaning efficiency of swept (470 kHz) and traditional (430 kHz) megasonic cleaning


FIGURE 2.31 Defect number after various cleaning processes [36]


FIGURE 2.32 Particle residue by type after various cleaning processes [36]

Copyright 2011 Elsevier Inc. All rights reserved. Chapter 2 R. Nagarajan, S. Awad and K.R. Gopi.

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Transcript of Copyright 2011 Elsevier Inc. All rights reserved. Chapter 2 R. Nagarajan, S. Awad and K.R. Gopi.