On-chip microscopic corrosion, originating from contact of dissimilar metals, can cause serious reliability issues for integrated circuits and microelectromechanical devices. A new micropattern corrosion screening method combined with Tafel plots were employed to study Cu bimetallic corrosion in acid and base solutions relevant to the chemical-mechanical planarization process. The results demonstrated that Cu corrosion on Ru is much more severe compared to Cu corrosion on Ta substrates. Tafel plots confirm the nobility trend of Ru [ Cu [ Ta. The micropattern corrosion study shows the Cu bimetallic corrosion depends on specific chemicals and bimetallic contacts. Strong complexing ligands like NH 3 combined with energetically favorable Cu/Ru bimetallic contact promote faster Cu corrosion under alkaline conditions (9 B pH B 11.4). Micropattern corrosion screening was shown to be useful in identifying the metastable surface layer during Cu corrosion and determining the optimal benzotriazole concentration for Cu corrosion inhibition.
Near-UV irradiation of hydrogen-terminated Si(111) wafers with the ruthenium-ruthenium bonded dinuclear compounds Cp 2 Ru 2 (CO) 4 (where Cp ) η 5 -MeC 5 H 4 , η 5 -C 5 Me 5 ) and [HB(pz) 3 ] 2 Ru 2 (CO) 4 [where HB(pz) 3 ) hydrotris(1-pyrazolyl)borate] in benzene solution at room temperature leads to the covalent attachment of CpRu(CO) 2 and HB(pz) 3 Ru(CO) 2 moieties to surface silicon sites on the wafer. ATR FTIR, XPS, and RBS data support the proposed Ru-Si bond formation as the dominant mode of wafer metallization. The surface area coverage of these ruthenized wafers is limited by the size the mononuclear ruthenium moiety that is attached to the Si anchor. A plausible reaction sequence involving the photochemically generated ruthenium-centered radicals CpRu(CO) 2 and [HB(pz) 3 ]Ru(CO) 2 that both activate the hydrogen-terminated Si(111) surface and combine with the resulting silicon radicals is presented and discussed.
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