Systematic Study of Surface Chemistry and Comprehensive Two-Dimensional Tertiary Current Distribution Model for Copper Electrochemical Deposition

Kim, Gwang-Soo; Merchant, T.; D’Urso, John; Gochberg, Lawrence A.; Jensen, Klavs F.

doi:10.1149/1.2337767

Cited by 12 publications

(16 citation statements)

References 31 publications

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“…10,30 In these models, kinetic parameters were acquired by analyzing the results of electrochemical measurement. 3,12,17 However, even if the ability to predict growth rate has evolved considerably, acquiring accurate parameters for Butler-Volmer kinetic model under complex operating conditions remains a challenge.Certainly, there is a relationship between results of electrochemical measurement and copper filling. And a trace amount of SPS in electrolyte is investigated with cyclic voltammetry by Yong-Da Chiu 31,32 and Qi Sun.…”

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confidence: 99%

“…A typical numerical model should have the ability to predict feature evolution of copper electrodeposition under different operating conditions. [10][11][12] The modified Butler-Volmer kinetic model, with purpose of accounting for behaviors of additives and cupric ion, is widely applied to describe the rate of copper electrodeposition. Generally, mainly the kinetic model consists of simulating the consumption of copper species, the influence of additives, and ultimately the local growth rate.…”

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confidence: 99%

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RETRACTED: Copper Electrodeposition in Through-Silicon Via under Galvanostatic Condition

Luo

Chen

Zhang

et al. 2016

J. Electrochem. Soc.

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We present a tertiary current-distribution model for copper electrodeposition under galvanostatic conditions, with detailed surface chemistry kinetics for the model system of copper electrodeposition. The values of the kinetic parameters are extracted from results of statistical chronoamperometry and linear sweep voltammetry experiments using a potential-dependent, diffusion-adsorptiondesorption model of the experimental system. The resulting surface chemistry description is combined with fundamental conservation laws, including mass transport, potential distribution, and competitive adsorption, to form the tertiary current distribution model. Two-dimensional finite element simulations of this model provide information about the causes of the thickness of the copper electrodeposition layer, including potential variations of the cathodic surface, fluctuations in the cupric ion concentration and coverage of the accelerator. The model is used to predict the filling process with different current densities and SPS concentrations and is verified by copper electrodeposition experiments. The "optimal zone" was determined for the SPS concentration and the inward current density to achieve good TSV filling. Sample points in the outer zone were selected and the failure mechanism was studied to help to infer the right direction toward the "optimal zone" in copper electrodeposition. The models are potentially useful tools for measuring the properties of electrolyte solutions and for the optimization of copper electrodeposition processes. Through-Silicon via (TSV) is one of key techniques for 3D integration with many advantages. The electroplated copper is a major interconnect material in TSV due to its high electrical conductivity, lower cost than alternative deposition methods.1,2 Copper electrodeposition as an efficient method of metallization is widely accepted, and it has been proposed by many researchers. [3][4][5] According to the feature of TSV on chip, some special additives such as accelerator (Bis-(3-sulfopropyl) disulfide, or SPS), suppressor (Polyethylene glycol, or PEG), leveler (Janus Green B) and Cl − , are usually applied in electrolyte solution to assist copper filling with void-free.6-8 An appropriate distribution of additives provides a fast growth at the bottom and the growth rate at via opening is suppressed, as improper distribution of additives result in unfilled feature.9 Hence, behaviors of additives on the cathode surface are very important for TSV filling process. However, there are still some challenges for establishing the optimal process for copper filling because the influence of feature of TSV, complicated mechanisms of additives behaviors and complicated fabricated process.2 A predictive numerical model of the copper electrodeposition process is a very helpful tool to investigate the optimal process with some advantages, such as low cost and efficiency. A typical numerical model should have the ability to predict feature evolution of copper electrodeposition under different operating conditi...

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RETRACTED: Copper Electrodeposition in Through-Silicon Via under Galvanostatic Condition

Luo

Chen

Zhang

et al. 2016

J. Electrochem. Soc.

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“…Some researchers have suggested that the inhibiting complex only blocks the substrate and does not participate as an intermediate in Cu 2+ reduction. [12][13][14][15][16] Other researchers have proposed mechanisms by which the complex fulfills both inhibiting and intermediate roles by being continually reformed during cathodic polarization. [17][18][19][20][21] It should be noted that if the second role applies, then Cu + necessarily is a constituent of the inhibiting complex.…”

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Inhibition of Copper Deposition by Polyethylene Glycol and Chloride

Garrido

Pritzker

2009

J. Electrochem. Soc.

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A physicochemical model for the effect of the additives polyethylene glycol ͑PEG͒ and Cl − on Cu 2+ reduction onto a rotating-disk electrode in acidic sulfate solutions has been developed and fit to experimental potential scans to estimate kinetic parameters. The model, which applies to either transient or steady-state conditions, incorporates diffusion, convection, and a reaction mechanism that explicitly includes the effects of both additives. Very good agreement between the fitted model and experimental data is obtained. The model captures the range of voltammogram shapes experimentally observed over a wide range of additive levels ͑i.e., from the gradual loss of Cu 2+ reduction inhibition with increasing overpotential at high PEG and Cl − concentrations to the sudden and complete breakdown of the inhibiting film at a critical potential when intermediate additive levels are used͒. An impedance model has also been derived and solved to generate impedance spectra using the previously obtained kinetic parameters. The predicted impedance spectra show good agreement with measured ones. Key aspects of the reaction mechanism are PEG desorption from the electrode, which occurs due to displacement by depositing copper, and the distinction made between the situations when the electrode is completely and partially covered by the inhibiting film.Polyethylene glycol ͑PEG͒ and chloride ions are commonly added to electroplating baths used in the electrodeposition of copper to improve the filling of trenches and vias in the Damascene processes for microelectronic circuit fabrication. 1-3 These two additives form a complex responsible for the selective inhibition of Cu 2+ reduction in particular regions of these features. There is not universal agreement concerning the structure of the inhibiting complex. Some researchers have presented evidence or interpreted experimental results on the basis that the complex contains PEG, Cl − , and Cu + , 4-8 whereas others have reported data supporting the view that copper is not necessarily a constituent of the complex. 9-11 Two different roles have been attributed to the inhibiting complex during copper electrodeposition: ͑i͒ blockage of sites available for the reduction of Cu 2+ and ͑ii͒ intermediate for the reduction of Cu 2+ . Some researchers have suggested that the inhibiting complex only blocks the substrate and does not participate as an intermediate in Cu 2+ reduction. [12][13][14][15][16] Other researchers have proposed mechanisms by which the complex fulfills both inhibiting and intermediate roles by being continually reformed during cathodic polarization. [17][18][19][20][21] It should be noted that if the second role applies, then Cu + necessarily is a constituent of the inhibiting complex.Numerous studies have been conducted to investigate the effect of PEG and Cl − concentration on the voltammetric response during Cu 2+ reduction. Broadly speaking, the cathodic scans fall into one of three categories, depending on additive concentration: ͑i͒ responses similar to those obs...

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“…It is known that when the current lower than the limiting current, the ohmic effect associated with electrode-surface screening by lm-formation/deposition is the predominant component. 2,4,[15][16][17] It can be predicted that the cavity wall surface conditions will play an important role in the potential distribution inside cavities, but which remained unveried experimentally.…”

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confidence: 99%

The actual potential distributions inside cavities under gas evolution and film formation conditions

Sun

Lin²,

Chen

et al. 2015

RSC Adv.

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Systematic Study of Surface Chemistry and Comprehensive Two-Dimensional Tertiary Current Distribution Model for Copper Electrochemical Deposition

Cited by 12 publications

References 31 publications

RETRACTED: Copper Electrodeposition in Through-Silicon Via under Galvanostatic Condition

RETRACTED: Copper Electrodeposition in Through-Silicon Via under Galvanostatic Condition

Inhibition of Copper Deposition by Polyethylene Glycol and Chloride

The actual potential distributions inside cavities under gas evolution and film formation conditions

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