Copper metallization technique

Electrolytic Precipitation. In 1800, 31 years before Faraday s fundamental laws of electrolysis, Cmikshank observed that copper metal could be precipitated from its solutions by the current generated from Volta s pile (18). This technique forms the basis for the production of most of the copper and 2inc metal worldwide. 

Lechtman, H. (1979), A pre-Columbian technique for electrochemical replacement plating of gold and silver on objects of copper,. Metals 31, 154—160. 

F. Y. Zhang, A. K. Prasad, and S. G. Advani. Investigation of a copper etching technique to fabricate metallic gas diffusion media. Journal of Micromechanics and Microengineering 16 (2006) N23-N27. 

The use of lithium aluminum hydride gives slightly lower yields and probably involves a displacement reaction by hydride ion. The zinc-copper couple technique probably involves formation of an organozinc intermediate. Sodium, magnesium, and aluminum metal may be used to replace the zinc-copper couple [59a, b]. These organometal intermediates react with aldehydes and... 

This is a very restricted oxidation state of copper but may be considered to occur in the polynuclear copper species Cu2, Cu3 and Cus, which have been characterized by matrix isolation techniques. Copper(O) also occurs in species formed by the reaction of copper metal vapour and carbon monoxide gas. Matrix isolation techniques have characterized a monomeric [Cu(CO)3] trigonal planar species and a dimeric [(CO)3CuCu(CO)3] species.32... 

Carbon monoxide chemisorption on copper metal is weak and for the most part reversible, and has been studied by a number of techniques... 

In this study, activated carbon fibers (ACFs) deposited by copper metal were prepared by electroplating technique to remove nitric oxide (NO). The surface properties of ACFs were determined by FT-IR and XPS analyses. N2/77K adsorption isotherm characteristics, including the specific surface area, micropore volume were investigated by BET and t-plot methods respectively. And, NO removal efficiency was confirmed by gas chromatographic technique. From the experimental results, the copper metal supported on ACFs appeared to be an increase of the NO removal and a decrease of the NO adsorption efficiency reduction rate, in spite of decreasing the BET S specific surface area, micropore volume, and micro-porosity of the ACFs. Consequently, the Cu content in ACFs played an important role in improving the NO removal, which was probably due to the catalytic reactions of C-NO-Cu. 

The evidence for the atom is now direct, as it is possible to see atoms directly, using such techniques as electron tunnelling microscopy. If this technique is used to look at the surface of copper metal, the atoms show up as bumps (Figure 2.1). The atom may be defined as the smallest unit of an element that retains the physical and chemical characteristics of the element. Dalton considered that the atom could be treated as a hard sphere that could not be broken down into smaller units, i.e. it had no internal structure, rather like a billiard ball. While this is not quite true, it can be understood in terms of the present knowledge of the structure of the atom. In the late 1800s, J. J. Thompson showed that the atom was built up from much smaller units, namely, electrons, protons and neutrons (Table 2.1). 

Knight shifts have been measured for Cu and Cu in metallic copper. NMR techniques have been used for the determination of electric field gradients in relation to point defects in metallic copper. Copper-65 NMR and Cu- AJ spin-echo, double-resonance measurements from Cu-exchanged ZSM-5 catalysts have shown the presence of Cu cations. Upon heating, auto-reduction of Cu to Cu was observed, with further reduction to the metal upon exposure to CO at high temperatures. Copper NMR was used to investigate the nanostructure of. ../Cu/CO/Cu... layers which had been prepared by different methods. ... 

Electrolysis is another important purification technique. The copper metal obtained by roasting copper sulfide usually contains impurities such as zinc, iron, silver, and gold. The more electropositive metals are removed by an electrolysis process in which the impure copper acts as the anode and pure copper acts as the cathode in a sulfuric acid solution containing Cu ions (Figure 20.6). The reactions are... 

Finally, the excess copper is polished away by means of CMP. This process step planarizes the surface and prepares it for the next level. The dual damascene technique can be repeated as many times as necessary, until the required number of copper metal layers are formed. 

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