Pulse-Reverse Electrodeposition of Cu for the Fabrication of Metal Interconnection

Kim, Myung Joon; Lim, Taeho; Park, Kyung Ju; Kim, Soo-Kil; Kim, Jae Jeong

doi:10.1149/2.016312jes

Cited by 15 publications

(13 citation statements)

References 31 publications

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“…Further, the impurities cause grain growth resulting in deteriorated mechanical properties, while also posing environmental concerns . Therefore, 'the required properties can be achieved by pulse reverse electrodeposition (PRED), in which the cathodic and reverse/anodic pulse parameters influence the texture, grain size, and type of grain boundaries. , PRED has several advantages − in that it (1) reduces the usage of additives, (2) refines grain size, (3) improves properties because of the lower residual stress, (4) minimizes impurities in the deposit, and (5) reduces adsorption of hydrogen species and results in less surface roughness versus that of the foils prepared by DC and PED. , Therefore, PRED can be a viable option for controlling the texture, refining the grain size and the type of grain boundaries, which is the main focus of this study. However, very limited work has been done on the use of PRED for controlling crystallographic orientations in copper, suggesting that no correlation has been made so far between the processing parameters and the properties of as-deposited copper.…”

Section: Introductionmentioning

confidence: 99%

Controllable Crystallographic Texture in Copper Foils Exhibiting Enhanced Mechanical and Electrical Properties by Pulse Reverse Electrodeposition

Pavithra

Sarada

Rajulapati

et al. 2015

Crystal Growth & Design

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The texture evolution in copper foils prepared by a rapid pulse reverse electrodeposition (PRED) technique using an 'additive-free' electrolyte and the subsequent correlation with the mechanical and electrical properties is investigated in the present study. Control over (111), (100) and (101) crystallographic textures in copper foils has been achieved by optimization of the pulse parameters and current density. Hardness as high as 2.0-2.7 GPa, while maintaining the electrical conductivity in the same range as that of bulk copper was exhibited by these foils. The complete study of controlling the (111), (100) and (101) textures, CSL Σ3 coherent twin boundaries, grain refinement and their effect on the mechanical and electrical properties is performed in detail by characterizing the foils with electron backscatter diffraction (EBSD), X-ray diffraction (XRD), nanoindentation and electrical resistivity measurements. PRED technique with short and high energy pulses enabled the (111) texture while increasing the forward off-time with optimized current density resulted in the formation of (100) and (101) textures. The reverse/anodic pulse applied after every forward pulse aided the minimization of residual stresses with no additives in the electrolyte, stability of texture in the foils, grain refinement and formation of growth-twins.Among the three highly textured copper foils, those with dominant (111) texture exhibited a lower electrical resistivity of ~1.65×10 -6 Ω-cm and better mechanical strength compared to those with (100) and (101) textures.

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Section: Introductionmentioning

confidence: 99%

Controllable Crystallographic Texture in Copper Foils Exhibiting Enhanced Mechanical and Electrical Properties by Pulse Reverse Electrodeposition

Pavithra

Sarada

Rajulapati

et al. 2015

Crystal Growth & Design

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“…The organic additives, which strongly interact with both the Cu surface and each other, preferentially promote the electrodeposition rate at the bottom of the feature being filled, leading to superfilling. [14][15][16][17][18] Different additives elicit different effects on the reduction rate of Cu, and can therefore be categorized as either suppressors or accelerators. The particular combination of accelerators and suppressors generally preferred for Cu superfilling consists of bis(3-sulfopropyl) disulfide (SPS) and polyethylene glycol (PEG) in the presence of chloride ion (Cl − ).…”

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confidence: 99%

Electrochemical Behavior of Citric Acid and Its Influence on Cu Electrodeposition for Damascene Metallization

Kim

Choe

Kim

et al. 2015

J. Electrochem. Soc.

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The electrolyte for Cu superfilling generally consists of copper sulfate, sulfuric acid, a chloride ion, an accelerator, and a suppressor. In this study, the characteristics of citric acid-based electrolytes and the interaction between citrate species and accelerators are investigated, with the ultimate goal being the replacement of both sulfuric acid and the suppressor with citric acid. Electrochemical impedance measurements were adopted to measure the changes in solution and charge transfer resistances with respect to citric acid and accelerator concentrations. In addition to a decrease in solution resistance resulting from the addition of citric acid, charge transfer inhibition was observed during Cu electrodeposition, which is likely the result of adsorption of citrate species onto Cu surface. A competitive adsorption between the citrate species and the accelerator was also observed and the new additive system was applied to the feature filling in the absence of the conventional polyethylene glycol suppressor. Using this new copper sulfate, citric acid, chloride ion, and accelerator system, trenches were successfully bottom-up filled, resulting in no internal defects.

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“…The previous studies have shown that the adsorption of SPS was closely associated with the chloride ions. 11,22,23,28,29 When the Cl − was added, a stable cuprous complex of CuCl would be formed on the surface, which was the preferential site for the adsorption of the SPS, forming a complex derivative of Cu-SPS-Cl − . The SPS could also directly adsorb on the sites of cuprous ions to form Cu + -SPS specie.…”

Section: Chloride Ion Dependent Adsorption Mechanism Of Single Peg An...mentioning

confidence: 99%

“…Hayase et al 20,21 reported that the reverse pulse could remove accelerator from copper z E-mail: qszhu@imr.ac.cn; xzhang14s@imr.ac.cn; czliu@sau.edu.cn surface with strong agitation and was helpful for a bottom-up filling of TSV using a Cu electrolyte with PEG-JGB-SPS additive system. Kim et al 22,23 reported that the anodic step promoted the displacement of PEG-Cl − by SPS at the early stage of electrodeposition and improved both superfilling and leveling performances. However, up to date, the operating mechanism of reverse pulse on the additive adsorption within the microvia is still unclear.…”

mentioning

confidence: 99%

Effect of Reverse Pulse on Additives Adsorption and Copper Filling for Through Silicon Via

Zhu

Zhang

Liu

et al. 2018

J. Electrochem. Soc.

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In order to develop the suitable Cu electrolyte for TSV filling using period pulse reverse (PPR) electroplating, the operating mechanism of reverse pulse on the adsorption of additives within TSV was systematically investigated. Whether the promotion or reduction of the adsorption of polyethylene glycol (PEG), bis (sodiumsulfopropyl) disulfide (SPS) and Janus Green B (JGB) by reverse pulse was determined by the charge of the formed complex of this additive with Cu + and Cl − . The charge of formed complex was dependent on the Cl − concentration. The reverse pulse had no significant effect on the adsorption of single JGB. In comparison, the composite JGB-PEG inhibitor could be repelled by reverse pulse at the microvia bottom. For the composite PEG-SPS or PEG-JGB-SPS, since the preferentially adsorbed Cu + -Cl − -PEG dense layer could effectively block the transportation of Cl − , few sites of Cl − were left for the SPS adsorption and then mainly formed positively charged SPS-Cu + , which accounted for the detachment of SPS by anodic pulse current at microvia entrance in the presence of PEG. Based on the change of the additives coverage surface by reverse pulse, the microvia filling performances in PPR plating compared to those in DC plating could be well explained. Three-dimensional integrated circuitry (3D-IC) with through Si via (TSV), is a promising technology to obtain vertical electric interconnection, high packaging density, faster signal transmission, and lower power consumption.1,2 The Cu filling by electroplating is one of the core and critical procedures in TSV fabrication. However, it is a great challenge in Cu electroplating to provide a void-free filling for the TSV with high aspect ratio (AR). The "super-filling" was widely used to obtain void-free filling for micro-sized blind via, i.e., the growth at micro-sized via or trench opening was limited and the growth at the bottom was accelerated, which could be enabled by special additives combination in Cu electrolyte.3-9 Several operating mechanisms of additives adsorption within microvia have been invoked to explain this super-filling process, such as the curvature enhanced accelerator coverage (CEAC) model, 3-5 the convection-dependent adsorption (CDA) model 6,7 and time-dependent transport-adsorption mode. 8,9 The commonly used additives can be divided into three categories: accelerator, such as bis (sodiumsulfopropyl) disulfide (SPS), inhibitor, such as polyethylene glycol (PEG), and leveler, such as Janus Green B (JGB). In addition, the chloride ion also played an essential role in Cu electrolyte to promote the additive adsorption, mass transport and Cu ion reaction. 10-13Another available approach for promoting void-free filling was the use of period pulse reverse (PPR) plating.14 Reverse pulse was an effective approach to mitigate the Cu ion depletion at the microvia bottom. 15,16 In the previous studies, Hong et al. 17 reported that an enhanced filling result was obtained by 3-step PPR using one additive. Sun et al. 18 reported that the PPR pl...

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Pulse-Reverse Electrodeposition of Cu for the Fabrication of Metal Interconnection

Cited by 15 publications

References 31 publications

Controllable Crystallographic Texture in Copper Foils Exhibiting Enhanced Mechanical and Electrical Properties by Pulse Reverse Electrodeposition

Controllable Crystallographic Texture in Copper Foils Exhibiting Enhanced Mechanical and Electrical Properties by Pulse Reverse Electrodeposition

Electrochemical Behavior of Citric Acid and Its Influence on Cu Electrodeposition for Damascene Metallization

Effect of Reverse Pulse on Additives Adsorption and Copper Filling for Through Silicon Via

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