Browsing by Author "Yagan, Rawana"

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    Master ThesisPublicationMetadata only
    Electrochemical evaluations of TiO2 nano films for advanced engineering applications
    (2018-05) Yagan, Rawana; Başım, Gül Bahar; Başım, Gül Bahar; Bebek, Özkan; Nizamoğlu, S.; Department of Electrical and Electronics Engineering; Yagan, Rawana
    This study evaluates the performance TiO2 nano-film for engineering applications, both in biomedicine and microelectronics, were Chemical Mechanical Planarization (CMP) is a main process used for planarizing the metal surface by producing such oxide nano-film that is known to be an intact and protective film. Titanium oxide nano-film evaluation in biomedical applications is investigated. Electrochemical experiments are done on biomedical grade Titanium plates such as Potentiostatic sweeps and potentiodynamic polarizations of Ti as a function of oxidizer concentration. In surface characterizations on TiO2 films two main methods are addressed; which are contact angle and wettability measurements and surface roughness measurements. CMP application on Ti surface is performed by controlling slurry oxidizer concentration. Which leads to material removal rate evaluations and surface characterization of chemical mechanical polished Ti surfaces. CMP is also a widely used process for the manufacturing of the microelectronic circuits. It is common to planarize the metallic layers such as tungsten in the transistor via and copper in the metallization lines. The integration of the metallization also involves the deposition of the barrier layers, which are necessary to stop the diffusion of metal to the transistor as well as to improve the adhesion of the metal to the underlying layers. In this study, titanium barrier CMP was thoroughly studied by electrochemical analyses with respect to the tungsten metal itself. Ti has the unique ability to form a protective oxide layer, which was characterized and analyzed under different oxidizer concentrations. Potentiodynamic and potentiostatic scans were performed in H2O2 to provide more information on the passivation and corrosion behavior under the selected conditions. Moreover, the effect of slurry solid loading in relation with oxidizer concentrations on the film formation and removal during the CMP was investigated for both materials. The application of corrosion behavior of Ti as barrier materials for W based interconnects was further studied by evaluating the surface wettability, roughness and topography analyses.
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    ArticlePublicationOpen Access
    A fundamental approach to electrochemical analyses on chemically modified thin films for barrier CMP optimization
    (IOP Publishing, 2019-04-09) Yagan, Rawana; Başım, Gül Bahar; Mechanical Engineering; BAŞIM DOĞAN, Gül Bahar; Yagan, Rawana
    Chemical Mechanical Planarization (CMP) process development for 10nm nodes and beyond demands a systematic understanding of atomic-scale chemical and mechanical surface interactions for the control of material removal, selectivity, and defectivity. Particularly the CMP of barrier/liner films is challenging with new materials introduced to better adhere the contact metal at the interface and limit the probability of metal diffusion to the transistors. The relative selectivity of the CMP removal rates of the barrier materials against the contact metal needs to be controlled depending on the integration scheme. This paper focuses on understanding the barrier CMP process selectivity on the model W/Ti/TiN applications through electrochemical evaluations and chemically modified thin film analyses. Ex-situ electrochemical evaluations are conducted on the W/Ti/TiN system to evaluate the passivation rates in various slurry formulations as a function of the slurry chemistry and the abrasive particle solids loading. Results of the passivation rates are compared to the removal rate selectivity and the post CMP surface quality on blanked W, Ti, and TiN films. A new methodology for CMP slurry formulations through ex-situ electrochemical analyses is outlined for new and more challenging barrier films while simultaneously highlighting an approach for corrosion prevention on the metallic layers.