Removal of Organic Films from Rotating Disks Using Aqueous Solutions of Nonionic Surfactants:  Film Morphology and Cleaning Mechanisms

Abstract

In this work, we consider the cleaning of an organic liquid film, consisting initially of a concentrated solution of abietic acid in isopropyl alcohol, from the surface of a rotating disk by using aqueous solutions of a nonionic surfactant, pentaethylene glycol mono-n-dodecyl ether. The results show that the removal process takes place in three consecutive stages. The first stage is controlled by the solubilization of the abietic acid by surfactant penetration and subsequent mass transfer from the interface to the bulk of the aqueous solution. During the first stage, the film absorbs water from the aqueous solution and breaks up into drops that leave portions of the surface exposed. The absorption of surfactant and water reduces the organic-phase viscosity, until the drops start to move on the disk surface under the action of shear forces. These drops aggregate into spiral-shaped continuous rivulets through which the organic phase flows until it comes off the disk edge. Such behavior occurs during the second stage of cleaning, which has a rate of removal appreciably faster than the first stage. The rivulets are shown to be tangent to the stress exerted by the aqueous solution on the surface of the organic phase. The rivulets eventually break, leading to a third stage with lower removal rates, in which the removal mechanism is apparently the roll up of organic-phase drops under the action of shear forces. In this work, we present experimental evidence that supports the described mechanism, based on photographs showing the morphology of the film structure in the different cleaning stages. A model is derived that relates the empirical observations of cleaning rates to physical parameters describing the solubilizing film hydrodynamics.

Removal of Organic Films From Rotating Disks Using Aqueous Solutions of Nonionic Surfactants: Effect of Surfactant Molecular Structure

“…In the rotating disk system, Beaudoin et al (9) and Kabin et al (11) observed that the cleaning process consisted of three successive stages. A typical cleaning curve is shown in Fig.…”

Microscopic model of nano-scale particles removal in high pressure CO2-based solvents

“…From Eqs. (13)(14)(15)(16)(17), we can see that surface tension and molar volume of the entrapped fluid decreased with increased pressure. The reduction in surface (a) Net adhesion force (NAF) between spherical Cu particle and silicon surface entrapped with isopropanol medium as a function of the pressure and particle radius in CO2 + isopropanol at 313.15 K. (b) Equilibrium separation distance (ESD) between spherical Cu particle and silicon surface entrapped with isopropanol medium as a function of the pressure and particle radius in CO2 + isopropanol at 313.15 K. tension decreases the fluid bridge force F fb , while the decrease in surface tension and the molar volume of the entrapped fluid increases the capillary pressure effect force F cpe .…”

“…Eqs. (6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16) were used to calculate the static forces of a particle on substrate under different pressures and temperatures. The solution of them employed Mathematica to obtain a series of data.…”

“…As many researchers pointed out, high solvent velocities impart high drag and shear forces that, if great enough, will overcome the particle adhesion and carry the particle into the bulk of detergent solutions [15][16][17]. However, the particles or residues in micronscale vias and trenches on the wafer have to be lifted into the bulk …”

Mechanisms of photoresist dissolution

“…Unlike benzoic acid, this resin is practically insoluble unless acid-base reaction ionizes the phenolic segments at the surface. The solubilization of fatty acids in aqueous detergent Ž solutions is one close parallel Chan et al, 1976;Kabin et al, . 1996 .…”