Influence of Molecular Weight of Polyethylene Glycol on Microvia Filling by Copper Electroplating

Dow, Wei‐Ping; Yen, Ming-Yao; Lin, Wen-Bing; Ho, Shih-Wei

doi:10.1149/1.2052019

Cited by 174 publications

(159 citation statements)

References 40 publications

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“…After 800 seconds, another leveler was injected into the electrolyte. 18 The filling performance of various formulas was characterized by a mean potential difference ( η) between the two polarization curves measured with the Cu RDE that was individually operated at 100 rpm and 1000 rpm. It was showed that if the copper plating formulas can perform bottom-up filling of a microvia, then a positive potential difference (i.e., η = E 100rpm −E 1000rpm > 0) occurs.…”

Section: Methodsmentioning

confidence: 99%

Optimization of the Copper Plating Process Using the Taguchi Experimental Design Method

Hsu

Dow

Chang

et al. 2015

J. Electrochem. Soc.

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Copper electroplating formulas composed of CuSO 4 , H 2 SO 4 , chloride ions, polyethylene glycol (PEG), bis (3-sulfopropyl) disulfide (SPS), and different levelers for microvia filling of a printed circuit board (PCB) were studied. The influence of the copper electroplating parameters, accelerator and leveler concentrations and cathodic current density on the microvia filling performance was explored using the Taguchi experimental design method. An L9 orthogonal array with four controlling factors at three levels was employed in the experimental design method. Variance analyses of the mean filling performance and the signal-to-noise ratio of the controlling factors showed that the most significant factor for the microvia filling performance was the leveler concentration. The other factors exhibited little to no effect on the microvia filling performance. The contribution of levelers to the filling performance was characterized using galvanostatic measurement and linear sweep voltammetry (LSV) with a working electrode at different rotational speeds. The experimental results indicated that the inhibiting effect of the levelers on the copper deposition was related to forced convection, which is a key physicochemical interaction for exhibiting good filling performance.

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Section: Methodsmentioning

confidence: 99%

Optimization of the Copper Plating Process Using the Taguchi Experimental Design Method

Hsu

Dow

Chang

et al. 2015

J. Electrochem. Soc.

Self Cite

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“…The suppression of deposition rate is also likely due to competition for active sites on the depositing surface by adsorptive PEG molecules [44]. In 2005, Dow et al [6] studied the influence of the molecular weight of PEG, and found that the higher the molecular weight of PEG, the stronger the suppression effect on the deposition rate of Cu. Suppressor adsorbs on the surface of the Cu deposit outside the hole, which can suppress the deposition rate of Cu outside the hole.…”

Section: Suppressormentioning

confidence: 99%

“…In TSV technology, Cu is used to fill the via as an interconnect. There are several matured techniques that can fabricate the Cu wire/interconnect, such as sputtering, evaporation, and electrochemical deposition, among which electrochemical deposition (also known as electroplating) is a cost-effective method capable of making uniform and hole-filling Cu metallization [1,[4][5][6]. In addition to basic constitutes such as sulfuric acid and copper sulphate, it is necessary to add several functional additives in the plating bath to assist or modulate the deposition of Cu atoms on non-planar substrates [7][8][9][10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Impurity Effects in Electroplated-Copper Solder Joints

Lee

Chen

2018

Metals

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Copper (Cu) electroplating is a mature technology, and has been extensively applied in microelectronic industry. With the development of advanced microelectronic packaging, Cu electroplating encounters new challenges for atomic deposition on a non-planar substrate and to deliver good throwing power and uniform deposit properties in a high-aspect-ratio trench. The use of organic additives plays an important role in modulating the atomic deposition to achieve successful metallic coverage and filling, which strongly relies on the adsorptive and chemical interactions among additives on the surface of growing film. However, the adsorptive characteristic of organic additives inevitably results in an incorporation of additive-derived impurities in the electroplated Cu film. The incorporation of high-level impurities originating from the use of polyethylene glycol (PEG) and chlorine ions significantly affects the microstructural evolution of the electroplated Cu film, and the electroplated-Cu solder joints, leading to the formation of undesired voids at the joint interface. However, the addition of bis(3-sulfopropyl) disulfide (SPS) with a critical concentration suppresses the impurity incorporation and the void formation. In this article, relevant studies were reviewed, and the focus was placed on the effects of additive formula and plating parameters on the impurity incorporation in the electroplated Cu film, and the void formation in the solder joints.

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“…65 The binding force between TU and PEG could retard the desorption of TU from PEG-covered Cu. Likewise, since the adsorption strength of PEG on the Cu surface increased with molecular weight, 66,67 high-molecular-weight PEG could effectively suppress the desorption of TU.…”

Section: [Tumentioning

confidence: 99%

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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Influence of Molecular Weight of Polyethylene Glycol on Microvia Filling by Copper Electroplating

Cited by 174 publications

References 40 publications

Optimization of the Copper Plating Process Using the Taguchi Experimental Design Method

Optimization of the Copper Plating Process Using the Taguchi Experimental Design Method

Impurity Effects in Electroplated-Copper Solder Joints

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

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