Tantalum and its nitrides are used in barrier layers in copper interconnected ultra-large-scale integrated circuits. However, due to the different physical and chemical properties of copper (Cu) and tantalum (Ta), the difference in removal rates is a problem. This study developed an acidic barrier layer slurry with better Cu/Ta rate-selective properties. During the research and development process, it is found that the introduced novel complexing agent, 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA), has a bisexual effect on Cu while effectively enhancing the Ta removal rate. Therefore, the detailed analysis was carried out on the mechanism of PBTCA on Cu/Ta. In this study, the effects of the slurry fundamental composition, include pH value, oxidant HO and complexing agent PBTCA, on Cu/Ta removal rate were firstly investigated by electrochemical and chemical mechanical planarization (CMP) experiments. Subsequently, XPS, SEM and AFM tests were utilized for in-depth analysis of the micro-activity mechanism of PBTCA. The concentration of PBTCA between 0.2 wt% and 0.3 wt% was found to have complexation effect on Cu, and the concentration between 0.3 wt% and 0.8 wt% was found to have corrosion inhibition effect on Cu, which verified that PBTCA has a dual effect on Cu. This phenomenon effectively reduces the difference of Cu/Ta removal rate and facilitates surface flattening. In addition, PBTCA is an environmentally friendly and biodegradable organophosphate condensate. Finally, the slurry stability experiments were carried out by average particle size and zeta potential tests. CMP experiments and atomic force microscopy (AFM) tests were employed to verify the performance of the slurry. It was concluded that the slurry was well stabilized with the oxidant addition, and the storage time had almost no effect on the removal rate and surface morphology of Cu and Ta. The results of the study provide a feasible method for barrier layer CMP.

中文翻译：

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2-膦酰丁烷-1,2,4-三羧酸 (PBTCA) 对阻挡层中 Cu/Ta 化学机械平坦化 (CMP) 的影响：一种新型络合剂及其对 Cu 的双重作用


钽及其氮化物用于铜互连超大规模集成电路的阻挡层。然而，由于铜（Cu）和钽（Ta）的物理和化学性质不同，去除率的差异是一个问题。本研究开发了一种具有更好的 Cu/Ta 速率选择性性能的酸性阻挡层浆料。在研发过程中发现，引入的新型络合剂2-膦酰基丁烷-1,2,4-三羧酸（PBTCA）对Cu具有双性作用，同时有效提高Ta去除率。因此，对PBTCA对Cu/Ta的作用机理进行了详细分析。在这项研究中，首先通过电化学和化学机械平坦化（CMP）实验研究了浆料基本成分（包括pH值、氧化剂H2O和络合剂PBTCA）对Cu/Ta去除率的影响。随后，利用XPS、SEM和AFM测试对PBTCA的微活性机制进行了深入分析。发现PBTCA浓度在0.2 wt%~0.3 wt%之间对Cu有络合作用,浓度在0.3 wt%~0.8 wt%之间发现对Cu有缓蚀作用,验证了PBTCA具有双重作用在铜上。这种现象有效地减小了Cu/Ta去除率的差异，有利于表面平坦化。此外，PBTCA是一种环保且可生物降解的有机磷酸酯缩合物。最后通过平均粒径和zeta电位测试进行浆料稳定性实验。采用 CMP 实验和原子力显微镜 (AFM) 测试来验证浆料的性能。 结果表明，氧化剂的添加使浆料得到了很好的稳定，并且储存时间对Cu和Ta的去除率和表面形貌几乎没有影响。研究结果为阻挡层CMP提供了一种可行的方法。