Effect of PEG molecular weight on bottom-up filling of copper electrodeposition for PCB interconnects

Yin, Likun; Liu, Z. H.; Yang, Zizhou; Wang, Z. L.; Shingubara, Shoso

doi:10.1179/174591910x12692711390390

Cited by 17 publications

(7 citation statements)

References 15 publications

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“…Typically, the suppressor is chosen from PEG or its derivatives [ 10 , 11 , 12 ], and the brightener is sodium bis-(3-Sulfopropyl)disulfide (SPS) or sodium 3-mercapto propane sulphonate (MPS) [ 8 , 13 ]. In contrast, there are a few levelers with quite different leveling performances [ 14 , 15 , 16 , 17 ] that are applied to various plating formulas to meet the multifarious demands of interconnecting manufacture.…”

Section: Introductionmentioning

confidence: 99%

Structure Performance Correlation of N-Heterocyclic Oligomer Leveler for Acid Copper Plating of Advanced Interconnects

Peng

Zhai

Chen³

et al. 2023

Molecules

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Levelers, as an essential part of organic additives in copper electroplating, play a crucial role in the fabrication of sophisticated interconnects in integrated circuits, packaging substrates, and printed circuit boards. In this work, four N-heterocyclic oligomers were synthesized and characterized, along with investigations of their electrochemical behaviors and their synergism with other bath components. The corresponding effects of the oligomers on the deposited copper films were analyzed by morphological and compositional characterizations. The leveling mechanism of the oligomers was further discussed with the aid of quantum chemical calculations. The results exhibit that each of these N-heterocyclic oligomers holds a particular degree of leveling ability. The oligomer of 1,3-bis(1-imidazolyl)propane and 1,3-dichloro-2-propanol (IPIEP) is the best leveler for THs plating compared with the other three oligomers. It was found that the hydroxyl group in IPIEP enhances the hydrophilicity of the modified molecule and triggers a more stable complexation between IPIEP and H2O−Cu(I)−MPS. Moreover, imidazole demonstrates a better practicality than piperazine. This work recommends the combination of N-heterocycles in planar conformation with modification by the hydroxyl group to synthesize high-performance straight-chain levelers.

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Section: Introductionmentioning

confidence: 99%

Structure Performance Correlation of N-Heterocyclic Oligomer Leveler for Acid Copper Plating of Advanced Interconnects

Peng

Zhai

Chen³

et al. 2023

Molecules

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“…In order to ensure that the micropores are filled with non-porous and are completely filled, copper needs to grow from the bottom of the blind hole step by step from the bottom to the top during the electrodeposition process, which is achieved through the coordination of several additives [5][6][7]. Currently, three types of additives including suppressor represented by macromolecular polyether compounds (such as polyethylene glycol (PEG) [8][9][10], polypropylene glycol [11,12]), accelerator represented by propane sulfonate derivatives (such as sodium 3-mercapto-1propane sulfonate [13,14] and bis (3-sulfopropyl) disulfide (SPS) [15][16][17]), levelers represented by heterocyclic or alkyl compounds (such as Janus Green B, Diazine Black and Alcian Blue [18][19][20]). Among them, suppressors with larger molecular chains combine with Cl − and are usually adsorbed on the surface of the circuit board to form a chelate with Cu 2+ or Cu + to inhibit the deposition rate of copper, thereby reducing the current density of the blind hole orifice [8].…”

Section: Introductionmentioning

confidence: 99%

“…Currently, three types of additives including suppressor represented by macromolecular polyether compounds (such as polyethylene glycol (PEG) [8][9][10], polypropylene glycol [11,12]), accelerator represented by propane sulfonate derivatives (such as sodium 3-mercapto-1propane sulfonate [13,14] and bis (3-sulfopropyl) disulfide (SPS) [15][16][17]), levelers represented by heterocyclic or alkyl compounds (such as Janus Green B, Diazine Black and Alcian Blue [18][19][20]). Among them, suppressors with larger molecular chains combine with Cl − and are usually adsorbed on the surface of the circuit board to form a chelate with Cu 2+ or Cu + to inhibit the deposition rate of copper, thereby reducing the current density of the blind hole orifice [8]. Contrary to suppressors, the accelerator with small molecular mass easily enters the bottom of the blind hole with the aid of Cl − , accelerates the deposition rate of copper at the bottom of the blind hole, and increases the current density at the bottom of the blind hole [16].…”

Section: Introductionmentioning

confidence: 99%

The effect of quaternary ammonium salts with different chain lengths on copper filling behavior in blind holes of printed circuit board

Shen¹,

Zhou²,

Huang³

et al. 2022

J. Micromech. Microeng.

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The rapid and defect free blind hole copper super filling is the key technology to ensure the quality and development of printed circuit boards (PCBs). The linear quaternary ammonium compounds with a low molecular weight are expected to act as a potential suppressor for blind hole copper filling. Here, three quaternary ammonium salts with different molecular chain lengths (the dodecyl trimethyl ammonium chloride, the cetyl trimethyl ammonium chloride and the stearyl trimethyl ammonium chloride) were selected to study the effects of the molecular chain length of quaternary ammonium salt on the copper filling behavior of the PCB blind holes. The electrochemical results show that the three quaternary ammonium salts show greater inhibition ability on copper deposition compared with the traditional additives (polyethylene glycol (PEG) and Cl−) and furthermore, the suppressor effect becomes stronger with the increase of molecular weight. The blind hole copper filling experiment of PCB is also carried out to study the copper filling capacity of three quaternary ammonium salts. The filling experiment reveals that compared with the traditional suppressors (PEG and Cl−), the filling quality of blind hole copper is significantly improved when the three quaternary ammonium salts are used as suppressors. Moreover, under the coordination of accelerator (bis (3-sulfopropyl) disulfide (SPS)), the three quaternary ammonium salts can realize more rapid copper super filling without chloride ion in the electrolyte. Cross-section and surface morphological analysis further illuminates that the quaternary ammonium salt as an suppressor can also more effectively inhibit the deposition of copper on the PCB surface and reduce the roughness of the copper layer. The present results imply that quaternary ammonium salts have greater advantages for copper filling and are expected to replace traditional suppressors as new suppressors.

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“…Defect-free filling, also called superfilling and superconformal deposition, can be mainly achieved by concentrating metal growth at the bottom of the concave structures to be filled with Cu. [1][2][3][4][5][6][7][8][9][10][11][12][13] The size of these structures varies from tens of nanometers (e.g. Damascene features) [14][15][16][17] up to hundreds of micrometers (e.g., microvias and through-holes in PCBs).…”

mentioning

confidence: 99%

“…Damascene features) [14][15][16][17] up to hundreds of micrometers (e.g., microvias and through-holes in PCBs). 11,12 This size variability of filling features has been resolved by modifying the organic additives that mainly drive bottom-up Cu filling. For the Damascene features, a combination of an accelerator and a suppressor is sufficient to achieve defect-free filling, whereas an additional organic leveler is necessary for microvias and through-holes.…”

mentioning

confidence: 99%

Bromide Ion as a Leveler for High-Speed TSV Filling

Sung

Yoon

Hong

et al. 2019

J. Electrochem. Soc.

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Organic levelers have been essential additives for Cu electrodeposition to achieve defect-free filling of through-silicon vias (TSVs). They selectively inhibit Cu deposition on top of TSVs, avoiding the occlusion of TSV openings and concentrating Cu deposition inside the TSVs. We recently reported that iodide ions (I − ) can act as an inorganic leveler to induce defect-free TSV filling. However, it was found that I − considerably decreased the efficiency of Cu electrodeposition because of the formation of an unstable CuI suppression layer on top of the wafer. The CuI layer easily detached from the wafer, and additional electrons were consumed to reestablish the suppression layer during gap-filling. This study introduces a TSV filling process with bromide ions (Br − ) as an alternative to I − . Although the suppression strength of Br − to Cu electrodeposition is weaker than that of I − , Br − forms a more stable suppression layer that does not reduce the efficiency of Cu electrodeposition, enabling high-speed TSVs filling. As a result, the filling rate with Br − was twice as fast as that with I − at the same applied current density; thereby TSVs 60 μm deep and 5 μm in diameter were completely filled in 500 s.

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Effect of PEG molecular weight on bottom-up filling of copper electrodeposition for PCB interconnects

Cited by 17 publications

References 15 publications

Structure Performance Correlation of N-Heterocyclic Oligomer Leveler for Acid Copper Plating of Advanced Interconnects

Structure Performance Correlation of N-Heterocyclic Oligomer Leveler for Acid Copper Plating of Advanced Interconnects

The effect of quaternary ammonium salts with different chain lengths on copper filling behavior in blind holes of printed circuit board

Bromide Ion as a Leveler for High-Speed TSV Filling

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