Effects of Triethanolamine and K4[Fe(CN)6] upon Electroless Copper Plating

In the paper, the effects of additives triethanolamine (TEA) and K4Fe(CN)(6) on the deposition rates and oxidation reduction potentials of electroless copper solution were investigated. The deposition rate of electroless copper was accelerated remarkably by an addition of TEA, and the acceleration mechanism was explored and demonstrated by a combination of linear sweep voltammetry and mixed potential theory. The oxidation current of formaldehyde decreased with an addition of TEA, but the reduction peak potential of [Cu(EDTA)](2-) was shifted to the positive direction, which resulted in a positive shift of the mix potential and an increase of mix current for electroless copper deposition. Meanwhile, we first confirmed that the reduction peak at -0.65 V was attributed to the reduction peak from [Cu[EDTA](2-) to metal copper from the deposition and mixed potential theory. The change in electroless copper deposition rate with K4Fe(CN)(6) concentration agreed with the change in formaldehyde reduction current with K4Fe(CN)(6) concentration, which indicated that the inhibition of K4Fe(CN)(6) for electroless copper was attributed to the inhibition of formaldehyde oxidation reaction. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3462980] All rights reserved.