The influence of thiourea on copper electrodeposition: Adsorbate identification and effect on electrochemical nucleation

Kang, Moon Seong; Kim, Soo-Kil; Kim, Keeho; Kim, Jae Jeong

doi:10.1016/j.tsf.2007.06.069

Cited by 63 publications

(48 citation statements)

References 21 publications

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“…C 1 in the equivalent circuit, is in the range of 0.1-0.5 lF cm -2 . The R ct values do not show any dependence on TU concentration, which is expected in the given range of its variation [20]. Generally, the double layer capacitance is expected to be in the range of 10-40 lF cm -2 [21].…”

Section: Impedance Analysesmentioning

confidence: 97%

Investigations on thiourea content in ternary Sn–Ag–Cu bath using electrochemical studies

Joseph

Phatak

2011

J Appl Electrochem

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We have developed a methane sulfonic acid (MSA) based ternary electrolytic bath for co-deposition of the eutectic Sn-Ag-Cu films. The bath contains thiourea (TU), which functioned as an effective chelating agent in controlling the bath stability as well as the elemental and microstructural properties of the deposited film. A study of the bath behaviour at TU concentrations in the range 0.06-0.2 M is undertaken with the help of elemental and microstructure analysis, cyclic voltammetry (CV) and impedance analysis. The deposited films have close to eutectic composition with slightly higher Cu content for all the TU concentrations. On the other hand, the microstructure is found to be increasingly refined with increasing TU content. The CV and impedance analysis confirm chelation of Ag and Cu with TU and absence of such chelation with Sn ions. It also indicates close deposition potentials for each metal ion. Impedance analysis specifically reveals presence of an adsorbed insulating film on cathode surface, contributed by MSA or water. It also reveals competitive deposition between the insulating film and metal ions.

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Section: Impedance Analysesmentioning

confidence: 97%

Investigations on thiourea content in ternary Sn–Ag–Cu bath using electrochemical studies

Joseph

Phatak

2011

J Appl Electrochem

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“…They may also influence the mechanism of electrocrystallization [5]. In this filed, organic substances, such as polyethylene glycol (PEG) [2,4], thiourea [6][7][8][9], benzotriazole [10,11], triethyl-benzyl-ammonium chloride (TEBA) [12], and saccharin [7], are widely used as leveling and brightening agents in copper electrodeposition in order to produce smooth, free of voids and porosity copper deposits. However, the research for better candidates as substitutes for these organic substances is continuing, since most of them are environmental unfriendly.…”

Section: Introductionmentioning

confidence: 99%

The effect of quaternary ammonium-based ionic liquids on copper electrodeposition from acidic sulfate electrolyte

Zhang

et al. 2014

J Appl Electrochem

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The effect of quaternary ammonium-based ionic liquids (ILs) including tetraethylammonium hydrogen sulfate (NEt 4 HSO 4 ) and tetrabutylammonium hydrogen sulfate (NBu 4 HSO 4 ) on copper electrodeposition from acidic sulfate electrolyte was investigated by cyclic voltammetry and chronoamperometric measurements. These ILs were found to have a blocking effect on the copper electroreduction and induced the formation of more leveled and fine-grained cathodic deposits. Analysis of the dimensionless current-time transients indicated that the electrodeposition of copper was involved with instantaneous threedimensional nucleation with diffusion-controlled growth. The addition of ILs induced the instantaneous nucleation to more progressive one. Data obtained from X-ray diffraction spectra revealed that the presence of these ILs strongly affected the crystallographic orientation of the electrodeposited copper with a (220) preferential orientation.

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“…1,2,[6][7][8][9][10][11][12][13][18][19][20][21][22][23][24][25][26][27][28][29] TU is a common additive in Cu and Ag electrodeposition baths and induces leveling and grain refining properties.…”

mentioning

confidence: 99%

“…1,2,6-13, [18][19][20][21][22][23][24][25][26][27][28][29] TU is a common additive in Cu and Ag electrodeposition baths and induces leveling and grain refining properties. [18][19][20][21][22][23][24][25][26] TU has been used as an additive either solely or in combination with Cl − (TU-Cl − ) in baths used for electrodeposition processes involving various current/potential waveforms such as direct current, pulse-, or pulsereverse waveforms.…”

mentioning

confidence: 99%

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Accuracy Improvement in Cyclic Voltammetry Stripping Analysis of Thiourea Concentration in Copper Plating Baths

Choe

Kim

et al. 2015

J. Electrochem. Soc.

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Cyclic voltammetry stripping (CVS) has been regarded as a powerful tool for monitoring the concentrations of organic additives in plating baths. In this study, the dilution titration (DT) method of CVS was modified to improve the measurement accuracy of thiourea (TU) concentrations in Cu plating baths. The conventional DT-CVS method cannot guarantee high accuracy because the electrochemical behavior of TU is concentration and potential dependent, which can cause disturbances in the response signals. In this study, by adding polyethylene glycol (PEG) as an organic additive, the undesirable electrochemical behavior of TU was suppressed and the accuracy of DT-CVS was greatly improved. Using the improved method, the concentrations of TU and its derivatives in the plating bath were measured. The errors between the real and measured concentrations were reduced from 15.0%, 36.0%, and 15.0% using the conventional DT-CVS method to within 3.00%, 6.00%, and 6.00% for TU, N-ethyl thiourea, and N ,N-diethyl thiourea, respectively, using the improved method. Organic additives are important constituents of the electroplating baths owing to their ability to control the morphology and the film properties of the plated material.1-17 The organic additives are typically grouped into suppressors, accelerators, and levelers, based on their roles and functionality.1-17 Examples of organic additives in electroplating baths include bis(3-sulfopropyl) disulfide, polyethylene glycol (PEG), janus green b (JGB), polyethylene imine (PEI), 1,2,3-benzotriazole (BTA), and thiourea (TU). 1,2,[6][7][8][9][10][11][12][13][18][19][20][21][22][23][24][25][26][27][28][29] TU is a common additive in Cu and Ag electrodeposition baths and induces leveling and grain refining properties.18-26 TU has been used as an additive either solely or in combination with Cl − (TU-Cl − ) in baths used for electrodeposition processes involving various current/potential waveforms such as direct current, pulse-, or pulsereverse waveforms. 20,21,23,24 Various applications of TU as an additive have been studied, including the formation of the Cu twin, Ag superfilling, and the fabrication of CuS nanowire structures. 18,19,[23][24][25][26] TU is known to form thiolate complexes such as [Cu-(TU) ions. [27][28][29] Owing to the various derivatives and their different electrochemical responses, TU shows unique electrochemical behavior unlike typical suppressors or levelers. Although TU commonly reduces the Cu deposition rate, it often acts in an opposite role as an accelerator under specific conditions such as low concentrations and low overpotentials. [27][28][29] Several mechanisms explaining the accelerating effect of TU have been proposed. [27][28][29] Generally, the reduction of Cu 2+ occurs in two steps, namely the reduction of Cu 2+ to Cu + , followed by the reduction of Cu + to Cu 0 . The first step has been known to be the rate-determining step. In the presence of TU, however, additional reactions occur, as described in Eq. 1. 29 They explained that the chain reaction...

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The influence of thiourea on copper electrodeposition: Adsorbate identification and effect on electrochemical nucleation

Cited by 63 publications

References 21 publications

Investigations on thiourea content in ternary Sn–Ag–Cu bath using electrochemical studies

Investigations on thiourea content in ternary Sn–Ag–Cu bath using electrochemical studies

The effect of quaternary ammonium-based ionic liquids on copper electrodeposition from acidic sulfate electrolyte

Accuracy Improvement in Cyclic Voltammetry Stripping Analysis of Thiourea Concentration in Copper Plating Baths

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