Electrodeposition of Copper for Three-Dimensional Metamaterial Fabrication

Abstract

Metamaterials typically consist of metallic and dielectric repeating structures. Electrodeposition of copper is the preferred approach to fabricating the metallic part of the metamaterials of interest in this study. The highly variant topography requires chemical additives, like chloride ions, 3-mercapto-1-propanesulfonic acid (MPSA), polyethylene glycol (PEG), and polyvinylpyrrolidone (PVP) to enhance bottom-up superfilling while maintaining terrace flatness. This study focuses on both experimental and computational investigations of the degradation potential of the additives and their adsorption mechanism in a highly acidic copper electrolyte in order to optimally parametrize the copper electrodeposition process. Results show Cl-MPSA-PEG-PVP additives perform well, but substitution of PVP with Janus Green B provides better terrace leveling. Additionally, NMR data show a quick and complete conversion of MPSA to bis(3-sulfopropyl) disulfide (SPS) in the acidic copper bath. Finally, FEM simulations further show that the accelerator species may initially accumulate and be transported vertically until overplating, whereby they are transported laterally.

Advances in mechanistic understanding of additives for copper electroplating in high-end electronics manufacture

“…恰当的添加剂 配方可以改变电极表面的极化电位, 调控孔内外不 同区域铜沉积的速率, 从而实现无孔隙的超级填充 (Superfilling), 科学上将这一类的现象归纳为电镀 铜填盲孔的问题 [11] (图 2). [12][13][14][15][16][17][18] , 聚乙烯亚胺(PEI) 、聚乙烯吡咯烷酮(PVP)等含氮 聚合物 [19][20][21][22] 、以及十二烷基三甲基氯化铵(DTAC) 等季铵盐类表面活性剂 [23,24] , 能够起到抑制消除镀 层上方的凸起(Bump)的形成的作用. 针对不同的电 镀铜应用场景, 产业界需要优化出特定配方和施镀 条件, 而这绝非易事.…”

“…Broekmann 等 人则利用 NMR 研究了 3,3-硫代双-1-丙烷磺酸 (TBPS) 作为加速剂的作用机理 [113112] , 还研究了聚乙烯吡咯 烷酮(PVP)作为可调变的整平剂在大马士革电镀铜 工艺中的应用 [114113] , 并对同时包含整平剂 Imep 和抑 制剂聚亚烷基二醇 (PAG) 官能团的新型添加剂 IPEG 展开了 NMR 和电化学研究，, 发现 IPEG 具有超强 的抑制能力 [115114] . Pinhero 等人报道了 NMR 和 IR 的 数据, 结果表明开路电位下加速剂 MPS 一旦加入酸 性铜镀液中就会被氧化为 SPS, 且该过程不可逆 [20] . [116115] .…”

Additive Manufacturing through Galvanoforming of 3D Nickel Microarchitectures: Simulation‐Assisted Synthesis

“…Nilson and Griffiths [12] added a detailed description of natural convection in templates and Chen and Evans [13] optimized moving boundaries in finite element method (FEM) simulation for electrodeposition. [16] Furthermore, 3D templates can shield and deflect electrolyte current density vectors inducing changes in local current density.To understand the aforementioned challenges, this work exploits 3D nanocrystalline nickel electrodeposition simulation built upon the previously mentioned 2D electrodeposition simulation studies. Pulsed electrodeposition, a frequently used technique to improve homogeneity of the deposits, was used and modeled by Yeh et al [15] Similar to the 2D LIGA process, 3D LIGA was used to create complex structures.…”

“…Large changes of the active area in vertical direction, bottleneck features within the templates, lateral diffusion and migration of the electrolyte constituents have to be considered. [16] Furthermore, 3D templates can shield and deflect electrolyte current density vectors inducing changes in local current density.To understand the aforementioned challenges, this work exploits 3D nanocrystalline nickel electrodeposition simulation built upon the previously mentioned 2D electrodeposition simulation studies. The simulation is verified by nickel electrodeposition from a nickel sulfamate electrolyte [17][18][19] into 3D microprinted electrode arrays.…”

“…Large changes of the active area in vertical direction, bottleneck features within the templates, lateral diffusion and migration of the electrolyte constituents have to be considered. [16] Furthermore, 3D templates can shield and deflect electrolyte current density vectors inducing changes in local current density.…”