Joshua J. Adler

Capillary forces between surfaces with nanoscale roughness

The flow and adhesion behavior of fine powders (approx. less than 10 microm) is significantly affected by the magnitude of attractive interparticle forces. Hence, the relative humidity and magnitude of capillary forces are critical parameters in the processing of these materials. In this investigation, approximate theoretical formulae are developed to predict the magnitude and onset of capillary adhesion between a smooth adhering particle and a surface with roughness on the nanometer scale. Experimental adhesion values between a variety of surfaces are measured via atomic force microscopy and are found to validate theoretical predictions.

Effect of Particle Size of Chemical Mechanical Polishing Slurries for Enhanced Polishing with Minimal Defects

In this study the effects of oversize particle contamination in chemical mechanical polishing (CMP) slurries were investigated on the silica CMP process. The limits of light scattering technique were established in detecting coarse particles in a commercial silica CMP slurry using two different methods. The detection limits were set by observing the shift in particle size distribution curve or by the appearance of an additional peak in the particle size distribution curve of the baseline slurry when a known amount of coarser particles were added to it. Simultaneously, polishing tests were conducted by spiking the base slurry with coarser sol‐gel silica particles at the established detection limits. It was observed that the contamination of larger particles not only created surface damage but also changed the material removal rate. The mechanism of polishing in the presence of larger size particles is discussed as a function of particle size and concentration.

Measurement of oil-mediated particle adhesion to a silica substrate by atomic force microscopy

Preventing particle segregation while maintaining flow is critical to enable processing in a variety of industries. Where segregation or dusting is particularly troublesome, oil may be added to the powder to increase cohesion between particles or to attach flow-aids to the particle surface. In this investigation, the role of the capillary force produced by an oil annulus between surfaces and its influence on adhesion are explored. The results of direct measurement by atomic force microscopy are compared with ensemble powder properties, as well as a simple theoretical expression that predicts the magnitude of the adhesion force as a function of the separation distance. Agreement is achieved between theory and experimental data using only the volume of the oil annulus and its surface tension as variables.

Surface interaction forces in chemical-mechanical planarization

Abstract Understanding the role of surface intra-molecular forces is critical in a variety of aspects of chemical-mechanical polishing technology. In this paper we explore some of the critical areas where this is an important parameter, such as material removal mechanisms in oxide polishing. Particular attention is given to the use of coupling single particle atomic force microscopy experiments with FTIR and TEM studies of polished oxide surfaces in studying the possible role of surface hydration effects in chemical-mechanical planarization of oxide thin films.