Browsing by Author "Vakarelski, I. U."

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Studies on slurry design fundamentals for advanced CMP applications
(ECS, 2013) Başım, Gül Bahar; Karagöz, Ayşe; Özdemir, Zeynep; Vakarelski, I. U.; Chen, L.; Mechanical Engineering; BAŞIM DOĞAN, Gül Bahar; Karagöz, Ayşe; Özdemir, Zeynep
New developments and device performance requirements in microelectronics industry add to the challenges in chemical mechanical planarization (CMP) process. One of the recently introduced materials is germanium which enables improved performance through better channel mobility in shallow trench isolation (STI) applications. This paper reports on the slurry design alternatives for Ge CMP with surfactant mediation to improve on the silica/germanium selectivity using colloidal silica slurry. In addition to the standard CMP tests to evaluate the material removal rates, atomic force microscopy (AFM) based wear tests were also conducted to evaluate single particle-surface interaction of the polishing system. Furthermore, nature of the surface oxide film of germanium was studied through contact angle measurements and surface roughness tested by AFM. It was observed that the CMP selectivity of the silica/germanium system and defectivity control were possible with a reasonable material removal rate value by using self-assembled structures of cationic surfactants.
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Tailoring silica nanotribology for CMP slurry optimization: Ca2+ cation competition in C12TAB mediated lubrication
(ACS, 2010-04-12) Vakarelski, I. U.; Brown, S. C.; Başım, Gül Bahar; Rabinovich, Y. I.; Moudgil, B. M.; Mechanical Engineering; BAŞIM DOĞAN, Gül Bahar
Self-assembled surfactant structures at the solid/liquid interface have been shown to act as nanoparticulate dispersants and are capable of providing a highly effective, self-healing boundary lubrication layer in aqueous environments. However, in some cases in particular, chemical mechanical planarization (CMP) applications the lubrication imparted by self-assembled surfactant dispersants can be too strong, resulting in undesirably low levels of wear or friction disabling material removal. In the present investigation, the influence of calcium cation (Ca2+) addition on dodecyl trimethylammonium bromide (C12TAB) mediated lubrication of silica surfaces is examined via normal and lateral atomic force microscopy (AFM/LFM), benchtop polishing experiments and surface adsorption characterization methods. It is demonstrated that the introduction of competitively adsorbing cations that modulate the surfactant headgroup surface affinity can be used to tune friction and wear without compromising dispersion stability. These self-healing, reversible, and tunable tribological systems are expected to lead to the development of smart surfactant-based aqueous lubrication schemes, which include designer polishing slurries and devices that take advantage of pressure-gated friction response phenomena.