The Effects of Particle Adhesion in Chemical Mechanical Polishing
- PDF / 214,815 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 48 Downloads / 217 Views
F3.5.1
The Effects of Particle Adhesion in Chemical Mechanical Polishing Zhenyu Lu, S.V. Babu, and Egon Matijević Departments of Chemistry and Chemical Engineering Center for Advanced Materials Processing Clarkson University, Potsdam, NY 13699 Abstract The properties of abrasive particles, and their interactions with surface films to be polished, play a key role in chemical mechanical polishing (CMP). This study applies the packed column technique for the investigation of the adhesion phenomena at the particle/film interface as a function of different slurry chemistries relevant to polishing processes. Well-defined dispersions, including uniform spherical silica and silica cores coated with nanosized ceria, as well as calcined alumina were used to represent slurry abrasives, and copper or glass beads to simulate wafers or discs. It was shown that the pH and slurry flow rate had significant effects on particle attachment and removal. The results of deposition of silica particles on copper beads in the presence of various concentrations of H2O2 and of detachment from copper beads of alumina particles, loaded at different pH values, had strong correlations to the polish rates of the metal. 1. INTRODUCTION The packed column technique [1] is well suited for the studies of the transport phenomena of colloidal particles through granular media, which consist of much larger uniform beads. The method allows for the elucidation of the mechanisms of interactions of finely dispersed matter in contact with solid substrates, and of chemical reactions between such solid and solutions injected in the system [2,3]. Based on such experimental results and their theoretical interpretations, it is possible to gain a better understanding of a number of phenomena related to CMP in different systems, both from physical and chemical points of view. The common abrasive particles used in CMP of copper and silicon oxide wafers (alumina, silica, ceria, etc.) have been generally polydispersed, and usually of irregular shapes [4-6]. In this study, well-defined dispersions of uniform particles, including those of spherical silica and silica cores coated with nanosized ceria, as well as of polydispersed calcined alumina, were used to follow particle adhesion on copper and glass beads. Some adhesion results were compared with polish rate results to establish the correlation between the two processes. 2. EXPERIMENTAL 2.1. Materials Five samples of monodispersed silica spheres of different diameters (ranging from 50 nm to 400 nm) were supplied by the Nissan Company. A slurry of calcined alumina having a mean size of 200 nm and a density of 3.7 g cm-3 was provided by Ferro Corporation. Silica (400 nm in diameter) coated with nanosized ceria was prepared as described previously [7].
Downloaded from https://www.cambridge.org/core. UNSW Library, on 19 Apr 2020 at 10:16:47, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1557/PROC-767-F3.5
F3.5.2
2.2. Packed Column Technique The packed c
Data Loading...
