微电铸工艺中含N’N-二乙基硫脲添加剂时金属铜填洞机理研究

为了研究含N’N-二乙基硫脲添加剂的微电铸工艺金属铜填洞机理，本文采用线性伏安法、循环电压电流溶出法(CVS)、扫描电镜(SEM)以及XRD测量法研究N’N-二乙基硫脲对微电铸工艺电化学行为的影响，并借助塔菲尔方程，研究微电铸铜反应过程中的电极动力学参数。结果显示：当微电铸铜工艺中加入N’N-二乙基硫脲添加剂时，产生活性极化，提高了铜离子还原时所需的活化能，金属离子的放电速度从2.2214 mA/ cm2降低 到约0.076 mA/ cm2，这样增加了反应时的过电位，促使电极表面晶核成型速度增加，晶体成长速度由2.57μm /min 降低到约0.17μm /min，铜离子的平滑能力提高约50%。这样可以有效减小微电铸时的边沿效应，使金属铜具有良好的填充微型孔洞的能力。本实验通过微电铸工艺成功地将金属铜填充入宽为10μm，深宽比为4：1的微型凹槽中，且镀层内没有空洞、空隙以及细缝等缺陷。

Research on copper gap-filling in micro electroplating process with N'N-diethylthiourea

In order to investigate the copper gap-filling in micro electroplating process with additive(N'N-diethylthiourea),the electrochemical behaviors of electrolyte were analysed by SEM,CVS and XRD,and the electrode dynamic parameters were studied by the Tafei equation.The results show that when N'N-diethylthiourea is used in micro electroplating copper process,an activation polarization is generated to improve the activation energy,the metal ion discharge rate is lowered from 2.221 4 mA/cm2 to about 0.076 mA/cm2.Therefore,the overpotential is increased,and the crystal nucleus molding speed on the electrode is accelerated;so that the crystal growth speed is decreased from 2.57 μm/min to about 0.17 μm /min,and the leveling ability is increased about 50%.Experiments show that the side effect is lowered effectively,which makes the copper ions get a good filling ability for micro-trenches.Furthermore,some micro trenches in the silicon wafer with the width of 10 μm and aspect ratio of 4:1 are filled by metal copper in micro electroplating process with N'N-diethylthiourea,the electroplating layer have no voids or seams.