Berlin 2008 – scientific programme

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O: Fachverband Oberflächenphysik

O 68: Metal Substrates: Solid-Liquid Interfaces

O 68.3: Talk

Thursday, February 28, 2008, 13:45–14:00, MA 043

Additives for the copper damascene process - in-situ ECSTM and XPS studies — •Knud Gentz¹, Sascha Hümann¹, Stefan Breuer¹, Ralf Hunger², Klaus Wandelt¹, and Peter Broekmann¹ — ¹Institute of Physical and Theoretical Chemistry, Bonn University — ²Institute of Material Research, Technical University of Darmstadt

Copper has become a focus of research activities over the last two decades due to its use as interconnect material in microchip design. Presently the dimensions of circuit layout is dependent on the wavelength of the applied light. To continue the ongoing process of miniaturization, cationic organic molecules have been studied as additives in the copper damascene process. In the present investigation the influence of various halides on structure and reactivity of a Diphenylviologen (DPV) layer adsorbed on a Cu(100) surface have been studied by in-situ electrochemical STM and high-resolution XPS, conducted at the synchrotron source BESSY2.

N,N'-diphenyl-4,4'-bipyridinium (Diphenylviologen, DPV) spontaneously adsorbs on a halide-modified Cu(100)-surface, forming a striped pattern , which has been characterized by in-situ Scanning Tunneling Microscopy. Cyclic Voltammetry indicates that the building block is the radical cation of the viologen. These result have been confirmed by ex-situ high resolution XPS after transfer into UHV in a process allowing conservation of the surface redox-states upon emersion. A careful analysis of the N1s and C1s core level shifts then allows the determination of the redox-state of the adsorbed viologens.