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Title:In-situ electrochemical spectroscopy and probe microscopy studies of electrodeposition
Author(s):Hatch, Jeremy J.
Director of Research:Gewirth, Andrew A.
Doctoral Committee Chair(s):Gewirth, Andrew A.
Doctoral Committee Member(s):Girolami, Gregory S.; Braun, Paul V.; Bailey, Ryan C.
Department / Program:Chemistry
Degree Granting Institution:University of Illinois at Urbana-Champaign
copper deposition
chromate deposition
surface enhanced raman spectroscopy
surface enhanced Raman spectroscopy (SERS)
electrochemical scanning tunneling microscopy (ec-stm)
scanning tunneling microscopy
copper plating
Abstract:Electrodeposition is widely used for industrial applications to deposit films, coatings, and adhesion layers. The diversity of materials that can be deposited has led to numerous studies of electrodeposition processes. This thesis explores two electrochemical systems: 1) the electrodeposition of chromate to form thin films on Au, and 2) the effect of functionalization and concentration on the behavior of quaternary ammonium levelers proposed for electroplating Cu in through-silicon vias (TSVs). The first study investigates the mechanism and morphology of chromate deposition, a process of which has significant importance both industrially and environmentally. Electrodeposition of chromate on Au was studied using cyclic voltammetry (CV), surface enhanced Raman spectroscopy (SERS), in-situ electrochemical scanning tunneling microscopy (EC-STM), and in-situ electrochemical atomic force microscopy (EC-AFM). CV results show the evolution of the deposited species as a function of scan cycle. SERS reveals the presence of intermediate species during the deposition process as well as the dual mixed CrIII/CrVI nature of the surface oxide film that is formed. In-situ EC-AFM shows that the reduced form of the oxide film, -Cr2O3, is oriented in a (3×3)R30° adlattice relative to the Au(111) surface. A mechanism for the electrodeposition of chromate on Au is proposed based on the results of this study. The second electrochemical system explored in this thesis revolves around Dodecyltrimethyl ammonium bromide (DTAB), benzyldimethylhexadecyl ammonium chloride (BDAC) and thonzonium bromide (ThonB) and their potential use as leveling additives. Electroplating measurements show that while each of the proposed levelers inhibits the onset of bulk Cu deposition at a Cu(poly) disk electrode, the concentration and potential dependence of this behavior depends on the functionalization of the additive. Surface enhanced Raman spectroscopy (SERS) results show that DTAB displays no potential dependent behavior, while both BDAC and ThonB exhibit substantial potential dependent behavior, the nature of which depends on headgroup functionality. This study demonstrates that functionalization of amphiphilic quaternary ammonium surfactants can have a significant impact on the effectiveness of the leveler.
Issue Date:2011-08-25
Rights Information:Copyright 2011 Jeremy J. Hatch
Date Available in IDEALS:2011-08-25
Date Deposited:2011-08

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