Influence of the Hydrophobic Groups on Quaternary Ammonium Additives for Copper Electrodeposition

Abstract

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 ...

Structural Influence of Terminal Functional Groups on TEG-Based Leveler in Microvia Filling

“…These potential oscillations are considered to be the repeated construction and destruction of a complex layer between a certain additive and accelerator. 23,39,40 Therefore, this phenomenon that was similarly observed in other injection conditions might be related to the instability of the inhibition layer during the competitive adsorption between Lev 3 and SPS. On the other hand, Fig.…”

“…Among the additives, levelers play a key role in void-free filling of microvias based on the convection-dependent adsorption behavior, like the position dependency on vias. 2,19,21,22 Recent studies report that the inhibition effect of levelers can be varied by the structure of levelers, such as functional groups, 19,[23][24][25] side chain length, [26][27][28] aromatic rings, 29,30 and counter ions. [31][32][33] Thus, studying the better understanding of the structure-property relationship of additives could assist in understanding the inhibition mechanism of levelers for achieving void-free filling and designing the new levelers.…”

“…First, the ammonium groups with halide counter ions were chosen. The positive charge of ammonium groups impeded the reduction of Cu 2+ ions adsorbing on the Cu surface, 23,26,29 which are considered to be origin of convection-dependent adsorption behavior. Second, the ethylene glycol unit, which is the monomer unit of most commonly utilized suppressor, PEG, was adopted.…”

Separation and determination of polyurethane amine catalysts in polyether polyols by using UHPLC–Q‐TOF‐MS on a reversed‐phase/cation‐exchange mixed‐mode column

“…N,N,N′,N′ ‐Tetramethyldipropylenetriamine (TMBPA) (purity >98%) and N ‐[2‐(2‐dimethylaminoethoxy)ethyl]‐ N ‐methyl‐1,3‐propanediamine (purity >98%) were obtained from Huntsman corporation and Evonik, respectively. N,N′ ‐Bis[3‐(dimethylamino)propyl]urea (purity >97% by GC–MS) was in‐house prepared followed a procedure as described previously with some modification.…”

Inhibiting Mossy Zinc Electrodeposits from Ammoniacal Media with Hydrophobic Tetraalkyammonium Salts

“…Among them, quaternary ammonium compounds (QACs) have the potential to suppress various detrimental morphologies. [9][10][11][12][13][14][15][16] Lan et al chose tetraalkylammonium hydroxides to inhibit the growth of zinc dendrite in alkaline media, and found that the inhibition ability is dependent on the size of the alkyl groups and the concentration of additives. 11 Wang et al used the quaternary ammonium compounds with different functional groups as levelers for copper electrodeposition and concluded that increasing the length of alkyl groups can enhance the inhibition effect on metal deposition.…”