表面活性剂PEG6000对二元络合体系化学沉积铜的影响

Effect of PEG6000 on Electroless Copper in Dual-Ligands System

研究了表面活性剂聚乙二醇6000对乙二胺四乙酸(EDTA)/四羟丙基乙二胺(THPED)二元络合体系化学镀铜的过程和化学镀铜表面结构的影响。混合电位-时间测试结果表明,化学沉积过程分为三个区:诱发区、过渡区和稳定区。PEG6000使体系的混合电位负移趋势放缓,与表面活性剂在铜表面的吸附阻滞了对带电荷离子的吸附有关。线性扫描测试结果表明,阴极还原反应为控制步骤,PEG6000的吸附减缓了阴极还原反应,还原峰电流密度下降了约40%;铜化学沉积速率随着PEG6000浓度的提高呈线性下降趋势。SEM、EDS和XRD表征结果表明,化学镀铜的纯度较高,加入PEG6000使镀层呈现出明显的(220)晶面择优取向,且晶粒尺寸由77.7 nm减小到50.0 nm,有细化晶粒的作用。

The effect of surfactant polyethylene glycol(PEG)6000 on the electroless copper plating process in a bath of dual-ligands ethylenediamine tetraacetic acid(EDTA)/tetrahydroxypropyl ethylenediamine(THPED)was investigated by electrochemical method.Mixed potential-time curves indicate that the overall process can be divided into three districts:induction,transitional and stable region.PEG6000 can slowdown the negative shifting of electrode potential,which related to the retardation of the adsorption of charged ions resulted from the surfactant adsorption on the copper electrode.Linear sweep voltammetry measurements show that cathodic reduction reaction is the controlling step for the plating process;PEG6000 could retard cathodic polarization,therewith,the peak value of cathodic reduction current decreased about 40%,so PEG6000 linearly reduced deposit speed.The copper layers prepared from the bath with PEG6000 are product of high-purity with a surface morphology of uniformly distributed fine particles,moreover,the addition of PEG6000 favored the formation of copper layer with(220)preferred orientation with refined grains of average size 50.0 nm,in comparison with 77.7 nm that from the bath without PEG6000 addition.