Oxidative Dissolution of Copper and Zinc Metal in Carbon Dioxide with tert-Butyl Peracetate and a β-Diketone Chelating Agent

Abstract

A series of beta-diketone ligands, R(1)COCH(2)COR(2) [tmhdH (R(1) = R(2) = C(CH(3))(3)); tfacH (R(1) = CF(3); R(2) = CH(3)); hfacH (R(1) = R(2) = CF(3))], in combination with tert-butyl peracetate (t-BuPA), have been investigated as etchant solutions for dissolution of copper metal into carbon dioxide solvent. Copper removal in CO(2) increases in the order tfacH < tmhdH < hfacH. A study of the reactions of the hfacH/t-BuPA etchant solution with metallic copper and zinc was conducted in three solvents: scCO(2) (supercrical CO(2)); hexanes; CD(2)Cl(2). The etchant solution/metallic zinc reaction produced a diamagnetic Zn(II) complex, which allowed NMR identification of the t-BuPA decomposition products as tert-butyl alcohol and acetic acid. Gravimetric analysis of the amount of zinc consumed, together with NMR studies, confirmed the 1:1:2 Zn:t-BuPA:hfacH reaction stoichiometry, showing t-BuPA to be an overall two-electron oxidant for Zn(0). The metal-containing products of the copper and zinc reactions were characterized by elemental analysis, IR spectroscopy, and, as appropriate, NMR spectroscopy and single-crystal X-ray diffraction [trans-M(hfac)(2)(H(2)O)(CH(3)CO(2)H) (1, M = Cu; 2, M = Zn)]. On the basis of the experimental results, a working model of the oxidative dissolution reaction is proposed, which delineates the key chemical variables in the etching reaction. These t-BuPA/hfacH etchant solutions may find application in a CO(2)-based chemical mechanical planarization (CMP) process.

Oxidative Dissolution of Metals in Organic Solvents

“…By dissolution of metals, tert -butyl peracetate was decomposed to tert -butyl alcohol and acetic acid. 133 The oxidative dissolution rate of copper was increased as the alkyl chain length in R 2 DTC – increased or as fluorine substitution was introduced for both the R 4 BAE and R 2 DTC – ligands. The Li(R 2 DTC) salts were more effective in copper removal than Na(R 2 DTC).…”

Bis(1,1,1,5,5,5-hexafluoropentane-2,4-dionato)tetrakis(μ4-1,1,1,5,5,5-hexafluoropentane-2,2,4,4-tetraolato)copper(II)octatin(II): a prospective precursor for Cu-doped SnO2films

“…For each tin centre, three of the Sn-O bonds are shorter with the distances ranging from 2.083 3 however, a comparison of Cu-O distances reveals that one of the bonds is more than 0.01 Å shorter [1.914 (3) Å ] in the unsolvated species. Elongation of Cu-O bonds is generally observed in Cu II -diketonates upon coordination of O-donor ligands (Xu et al, 2000;Maverick et al, 2002;Visintin et al, 2005;Pampaloni et al, 2005;Filyakova et al, 2009;Pointillart et al, 2010) in comparison with unsolvated species. In most cases, the effect is more pronounced than is observed in (I).…”

The Removal of Copper with Dialkyldithiocarbamate Ligands in Condensed Carbon Dioxide

“…This study showed that over a 20-hour period, a significant amount of copper could be removed. Several other studies were also quickly published that demonstrated various chelating agents and oxidants can remove copper from surfaces in CO 2 in a fairly reliable manner [2,[8][9][10][11]. Some studies also included the use of surfactants and cosolvents to help improve the removal of copper [12].…”