Particle adhesion with applications in microelectronics processing

Caitlin M Kilroy, Purdue University

Abstract

As the demand for smaller, faster and cheaper devices increases, developing a solid understanding of the adhesion of particles during the fabrication of semiconductor devices becomes increasingly important. Two processes can benefit from the modeling of such forces—chemical mechanical planarization (CMP) and extreme ultraviolet lithography (EUVL). Particle adhesion is dominated by two interaction forces: van der Waals dispersion force and electrostatic forces. van der Waals forces describe the attraction or repulsion of two surfaces interacting within a particular medium. Electrostatic forces result from the accumulation of surface charges at contact under the influence of Coulombic forces or diffuse double layer interactions. This work characterizes the adhesion forces for the interactions between rough surfaces of asymmetric geometry. This is accomplished using an adhesion simulation model which calculates the interaction between a particle of known geometry and substrate with FFT-generated roughness patterns. The adhesion of particles to a variety of EUVL-relevant substrates has been measured and evaluated. The effect of isopropyl alcohol on the adhesion of these substrates has been studied for the purpose of assisting in developing cryogenic cleaning technologies. A more rigorous method of evaluating the van der Waals force constant has been constructed. Finally, this work includes a preliminary characterization of the adhesion forces in electrochemical systems. These methods work toward improving descriptions of the forces between particles and substrates with rough, asymmetric features in a variety of different environments.

Degree

Ph.D.

Advisors

Beaudoin, Purdue University.

Subject Area

Chemical engineering

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