A series of quaternary ammonium compounds with different hydrophobic groups as spacers were synthesized. The influence of the hydrophobic groups on the additives for copper electrodeposition was investigated using a galvanostatic measurement on a RDE electrode. The increase of the length of the alkyl chain within the compounds enhances the suppressing capability. The introduction of a hydroxyl group or a phenyl ring into the hydrophobic groups in the molecular structures reduces the suppressing capacity. The results obtained from SEM measurements indicate that the presence of the quaternary ammonium compounds in the electrolytes may produce regular and relative leveling morphologies of copper deposits. The via-filling experiments without SPS exhibit that an almost complete filling was achieved for compound 1d (C 6 alkyl chain as a hydrophobic group), whereas a bad filling was obtained for compound 1a (C 3 -OH chain as a hydrophobic group). With SPS, the vias were perfectly filled both for compound 1a and 1d. However, the initial increment of growth was still conformal for the compound 1a. These results indicate the influence of the hydrophobic groups of the quaternary ammonium compounds on the filling behaviors and they are in agreement with the galvanostatic measurements at different electrode rotation speeds.Copper electrodeposition from acidic electrolytes has been widely used in electronic industry for both printed circuit board (PCB) and integrated circuit (IC) applications. The composition of the acidic electrolyte mainly contains cupric ion, acid and additives. Sulfuric acid or methanesulfonic acid (MSA) 1,2 is usually used as a supporting electrolyte. The presence of the additives in the electrolytes results in the improvement of the deposit properties, such as morphology, brightness, and grain refinement. Typically, the additives can be three (accelerator, suppressor, leveler) components for the filling of trenches and vias. 3,4 However, both suppressor and leveler can be taken as inhibiting additives due to their suppressing effect for copper deposition rate. 5 Because of the presence of convection-dependent adsorption (CDA), 5,6 the filling performance for via metallization can be improved by a leveler and the copper via-filling can be performed with a single organic additive. [7][8][9] Levelers are positively charged molecules 10 that produce the deposits topographical homogeneities in electrodeposition. The commonly used levelers in copper electrodeposition are nitrogencontaining or quaternary ammonium compounds including highmolecular weight molecules (e.g., JGB), 11 quaternary ammonium surfactants 12,13 and polymers. 14,15 Recently, a number of new quaternary ammonium compounds have been used as levelers such as Nbutyl-methyl piperidinium bromide, 16 diallylamine-type copolymer 7,8 and branched quaternary ammonium surfactant. 17 Quaternary ammonium compounds contain the quaternary nitrogen atoms in their backbones as the charged species and they also possess the attached hydrophilic or hydrophobic ...
The effect of intermolecular interaction of Phthalic acid (PA) and nonionic surfactants on electrodeposition was studied and the electrodeposition of tin was used as a model system. The CV curve of the electrolyte in the presence of a combination of PA and Triton X-100 (TX100) indicates that a relatively compact adlayer forms on the electrode surface and the electrodeposition of tin is inhibited very well. It is expected that the aromatic character of the hydrophobic moiety of both TX100 and PA enhance the binding interaction and the blocking effect is governed by the intermolecular interaction between PA and TX100. Scanning electron microscopic (SEM) image shows that a smooth, regular and compact deposit was obtained from the electrolyte with both PA and TX100. A relatively low carbon content of the deposit indicates that the incorporation of the additive in a deposit is strongly controlled in the presence of both PA and TX100. The possible explanation for the reduced incorporation may be proposed as the formation of the linkage of the molecules caused by intermolecular interaction between PA and TX100.
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