A phosphorus-containing new compound of tributyl(hexyl)phosphonium chloride (TBHP), but not the commonly used nitrogen-containing heterocycles and quaternary ammonium salts, is successfully applied for the superconformal copper filling of microvia in acid sulfate electroplating bath for the application of electronic industry. The molecular interaction mechanisms of TBHP combined with suppressor (polyethylene glycol, PEG) and accelerator (bis-(sodium sulfopropyl)-disulfide, SPS) are investigated in detail. Galvanostatic measurements at platinum rotation disk electrode indicate that the leveler of TBHP among with the suppressor and accelerator behaves the key characters of inhibition and convection-dependent adsorption during copper ions electroreduction for the bottom-up filling of microvia. Cyclic voltammetry measurements and FTIR spectroscopy further reveal that TBHP synergistically interacts with the suppressor to inhibit copper ions electroreduction at the mouth of microvia; while TBHP competes for adsorption with the accelerator, behaving as TBHP gradually replaced by the accelerator at the bottom. Based on the sufficient theoretical supports, the practical copper electroplating is conducted for the verification of microvia void free filling. In the developed novel copper plating formula containing TBHP, PEG and SPS, the void free filling is successfully achieved and the filling percentage (FP) is high in 95.5%.

中文翻译：

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三丁基（己基）氯化鏻作为微孔铜超保形电子电镀的新型整平剂


一种含磷新化合物氯化三丁基（己基）鏻（TBHP），而不是常用的含氮杂环和季铵盐，成功应用于酸性硫酸盐电镀液中微孔的超共形铜填充，用于电子工业。详细研究了 TBHP 与抑制剂（聚乙二醇，PEG）和促进剂（双（磺丙基）二硫化物，SPS）结合的分子相互作用机制。铂转盘电极的恒电流测量表明，TBHP 的整平剂与抑制剂和加速剂一起在铜离子电还原自下而上填充微孔过程中表现出抑制和对流依赖性吸附的关键特征。循环伏安测量和傅立叶变换红外光谱进一步表明，TBHP与抑制剂协同作用，抑制微孔口处铜离子的电还原；而TBHP与促进剂竞争吸附，表现为底部的TBHP逐渐被促进剂取代。基于充分的理论支持，进行了实际的电镀铜验证微孔无空隙填充。在开发的含有TBHP、PEG和SPS的新型镀铜配方中，成功实现了无空隙填充，填充率（FP）高达95.5%。