氯代十二烷基吡啶作为整平剂在盲孔镀铜中的应用研究

Application study on 1-dodecylpyridinium chloride as a leveling agent for blind via copper electroplating

摘要

[目的]以氯代十二烷基吡啶(LPC)为例，研究烷基吡啶类化合物作为电镀整平剂在盲孔填充中的应用可行性。[方法]通过密度泛函理论(DFT)计算、电化学测试、哈林槽电镀实验，以及扫描电子显微镜(SEM)和X射线衍射(XRD)等表征手段，研究LPC浓度对铜离子电沉积行为、盲孔填充效率及铜层微观结构的影响，并与传统整平剂健那绿(JGB)进行对比。[结果] DFT计算表明，LPC的能隙(3.057 eV)小于JGB(3.420 eV)，理论上更易吸附于铜表面，且其低电子密度集中于烷基链尾端，有利于形成疏水抑制层。电化学测试显示，LPC的质量浓度不高于8 mg/L时发挥去极化作用，促进铜沉积；LPC质量浓度增大至12 mg/L时转为抑制铜沉积，此时高低转速下的阳极氧化峰面积差(91.4 μC)和计时电位差(29.10 mV)均达最大。哈林槽电镀实验表明，LPC质量浓度为12 mg/L时盲孔的填充效率可达87.4%，优于同浓度JGB的75.6%。SEM和XRD分析证实，LPC的加入可细化铜层晶粒，促进Cu(111)晶面择优取向，在12 mg/L时表面最平整、Cu(111)晶面衍射峰强度最高。[结论] LPC作为小分子吡啶类整平剂在盲孔电镀铜中展现出良好的应用潜力。本研究为小分子烷基吡啶类化合物用作酸性镀铜整平剂提供了理论依据和数据支撑。

Abstract

[Objective] Taking 1-dodecylpyridinium chloride (LPC) as an example, this study investigates the feasibility of using alkyl pyridinium compounds as electroplating leveling agents in blind via filling. [Method] The effect of LPC concentration on the electrodeposition behavior of copper ions, blind via filling efficiency, and microstructure of copper coating was studied through density functional theory (DFT) calculations, electrochemical measurements, Haring cell plating experiments, and characterization by scanning electron microscopy (SEM) and X-ray diffraction (XRD), with a comparative study against the conventional leveling agent Janus Green B (JGB). [Result] DFT calculations revealed that LPC possessed a smaller energy gap (3.057 eV) compared with JGB (3.420 eV), suggesting theoretically stronger adsorption affinity toward the copper surface. Moreover, the low electron density of LPC was concentrated at the terminal end of the alkyl chain, facilitating the formation of a hydrophobic inhibition layer. Electrochemical measurements indicated that LPC acted as a depolarizer to promote copper deposition at mass concentrations not exceeding 8 mg/L, whereas it switched to inhibiting copper deposition when the mass concentration was increased to 12 mg/L. At this concentration, both the difference in anodic oxidation peak area (91.4 μC) and the difference in chronopotentiometric potential (29.10 mV) between high and low rotational speeds reached their maximum values. Haring cell electroplating experiments showed that a blind via filling efficiency of 87.4% was achieved at an LPC mass concentration of 12 mg/L, outperforming the 75.6% obtained with JGB at the same concentration. SEM and XRD analyses confirmed that the addition of LPC refined the copper grains and promoted the preferential orientation of the Cu (111) crystal plane, with the smoothest surface and the highest Cu (111) diffraction peak intensity attained at 12 mg/L. [Conclusion] As a small-molecule pyridine-based leveling agent, LPC demonstrates promising application potential for blind via copper electroplating. This study provides theoretical foundation and data support for the utilization of small-molecule alkyl pyridinium compounds as leveling agents in acidic copper plating systems.

关键词

印制电路板 / 盲孔 / 电镀铜 / 氯代十二烷基吡啶 / 整平剂

Key words

printed circuit board / blind via / copper electroplating / 1-dodecylpyridinium chloride / leveling agent

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基金资助

国家自然科学基金(22572126)