Stochastic Modeling of Polyethylene Glycol as a Suppressor in Copper Electroplating

Liu, Yang; Radisic, Aleksandar; Deconinck, Johan; Vereecken, Philippe M.

doi:10.1149/2.072405jes

Cited by 37 publications

(65 citation statements)

References 28 publications

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“…6, for larger molecular weight (θ * Cl = 0.2), the transition from the suppressed to the unsuppressed state occurs at a more cathodic potential. This tendency has also been found in the experiments by Yang et al, 14 Fig. 10a.…”

Section: Cyclic Voltammetry-the Simulations Insupporting

confidence: 85%

“…26 was able to reproduce the hysteresis in CVs by assuming additive incorporation in the deposit. To our knowledge, the first model, which predicts hysteresis without including additive consumption, was proposed by Yang et al 14 In their stochastic modeling approach, they also assumed the existence of a fractional Cl − coverage for complete PEG coverage. Adsorption and desorption of PEG was assumed to proceed in multiple steps and master equations were used to describe the probabilistic transition between different adsorption states.…”

Section: Cyclic Voltammetry-the Simulations Inmentioning

confidence: 99%

“…Our new model follows the lines of Yang et al 14 and takes into account, for the first time, the strongly nonlinear dependence of the suppression of copper deposition on the PEG surface coverage. This dependence is inferred from the PEG desorption experiments of Willey and West.…”

mentioning

confidence: 99%

“…In the case of electrolytes with PEG and Cl − additives, CVs frequently exhibit a hysteresis. [9][10][11][12][13][14] This means that the deposition current varies differently for forward and backward sweeping of the potential. Along with a hysteresis, a sudden change from a low-current to a high-current state often occurs during the forward (cathodic direction) sweeping, see for instance Fig.…”

mentioning

confidence: 99%

“…31 Moreover, instead of the detailed description of the multi-step co-adsorption kinetics in Ref. 14 we introduced in our model a nonlinear function to relate the maximally possible PEG surface coverage to a given chloride coverage. Despite the omission of additive consumption, the model is able to reproduce a series of characteristic features of CVs, measured under vastly different deposition conditions, as well as of special PEG adsorption and desorption experiments.…”

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confidence: 99%

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Copper Electroplating with Polyethylene Glycol

Yang

Dianat

Bobeth

et al. 2017

J. Electrochem. Soc.

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Additives play an important role in electrochemical deposition and understanding their working mechanism is a great challenge. In cyclic voltammetry measurements of copper deposition, hysteresis is ubiquitously observed. Correct prediction of hysteresis behavior is an important test for deposition models. In previous models, including poly(ethylene glycol) (PEG) and chloride ions as additives, a common assumption to explain the hysteresis is the consumption of additives during copper deposition. However, second-ion mass spectrometry measurements often detected comparatively low levels of impurities in deposits. Therefore, we propose here an alternative mechanism for explaining hysteresis curves without invoking additive consumption. Essential ingredients of our models are: (i) a strongly nonlinear dependence of the maximal possible PEG coverage on the chloride coverage on the copper surface, (ii) a nonlinear dependence of the deposition current on the PEG surface coverage, and (iii) an additional activation of the desorption of additives with increasing copper deposition current. We demonstrate that our model reproduces characteristic features of cyclic voltammograms measured under vastly different conditions and exhibiting pronounced hysteresis. Furthermore, simulations are compared well to PEG adsorption/desorption experiments with varying additive concentrations. The proposed model may serve to describe deposition situations with negligible additive consumption.

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Section: Cyclic Voltammetry-the Simulations Insupporting

confidence: 85%

Section: Cyclic Voltammetry-the Simulations Inmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Copper Electroplating with Polyethylene Glycol

Yang

Dianat

Bobeth

et al. 2017

J. Electrochem. Soc.

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Computational Investigation of the Adsorption of Polyalkylene Glycols on Copper Surfaces for Copper Electrodeposition

Schmidt

Knaup

Horsten

2019

Advcd Theory and Sims

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Adsorption of polyalkylene glycols such as polyethylene glycol (PEG) and polypropylene glycol (PPG) at the copper–water interface are studied in terms of simulations. The results are compared to spectroscopic data from available literature and reveal different contributions to the binding mode at the interface. The alignment of the polymers is determined by the interactions to both chloride‐covered copper surfaces and water. Adsorption is accompanied by conformational changes along the backbones of the molecules, which allow the observed alignment. Free energy surfaces of polymer fractions with copper ions reveal the formation of complexes with cuprous ions and support literature‐known experimental data that suggests contribution of such complexes to the adsorption. The detailed understanding of the binding mechanism of polyalkylene glycols to copper surfaces that results from this work is of crucial importance for the development of novel organic additives for electrolytic copper deposition, especially for demanding semiconductor applications.

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