Influence of Surface Oxide of Sputtered TaN on Displacement Plating of Cu
Influence of Surface Oxide of Sputtered TaN on Displacement Plating of Cu
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DOI：
10.1143/jjap.42.1843
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发表时间：
2003-04
影响因子：
1.5
通讯作者：
Zengling Wang;H. Sakaue;S. Shingubara;T. Takahagi
中科院分区：
文献类型：
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作者：
Zengling Wang;H. Sakaue;S. Shingubara;T. Takahagi
当用湿法化学蚀刻去除表面氧化层时，可以通过位移化学镀在TaN上沉积铜。为了应用于使用非常薄的TaN势垒膜的超大规模集成（ULSI）互连技术，必须形成具有最小天然氧化物厚度的稳定TaN膜。本文采用x射线光电子能谱（XPS）技术研究了溅射TaN薄膜在大气环境中的表面氧化。在Ar和N2混合气体中溅射TaN膜，其中Ar分压恒定在3.0 mTorr， N2分压变化。当N2分压低于0.5 mTorr时，TaN膜的表面氧化随时间的推移而提前。而当N2分压高于此值时，TaN膜的氧化停止在单层。我们证实，在N2分压高于0.5 mTorr时形成的TaN膜的氧化还原电位低于Cu膜的氧化还原电位，这表明在厚度小于10 nm的TaN膜上可以置换镀Cu。
Copper can be deposited on TaN by displacement electroless plating when a surface oxide layer is removed by wet chemical etching. For application to ultralarge-scale integrated (ULSI) interconnection technology in which very thin TaN barrier films are used, it is essential to form a stable TaN film with minimal native oxide thickness. In this study, we investigated surface oxidation of sputtered TaN films kept in air atmosphere by X-ray photoelectron spectroscopy (XPS) analysis. TaN films were sputtered in a mixture of Ar and N2 gases, where Ar partial pressure was kept constant at 3.0 mTorr and N2 partial pressure was varied. When N2 partial pressure was lower than 0.5 mTorr, surface oxidation of the TaN films advanced with time. However, when N2 partial pressure was higher than this value, oxidation of TaN film stopped at one monolayer. We confirmed that the redox potentials of TaN films formed with N2 partial pressures higher than 0.5 mTorr are lower than that of Cu, which suggests that displacement plating of Cu is possible on TaN films with thickness smaller than 10 nm.