Characterization of sputtered tungsten nitride film and its application to Cu electroless plating

• Published in: Microelectronic engineering Vol. 85; no. 2; pp. 395 - 400
• Main Authors: Wang, Zenglin, Liu, Zonghuai, Yang, Zupei, Shingubara, Shoso
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.02.2008; Elsevier Science
• Subjects: Applied sciences; Cu plating; Design. Technologies. Operation analysis. Testing; Electroless; Electronics; Exact sciences and technology; Integrated circuits; Reactive sputtering; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; WN barrier layer; XPS; Cu plating; Reactive sputtering; XPS; Electroless; WN barrier layer; Barrier layer; ULSI circuit; Electrochemical properties; Partial pressure; Interconnection; Integrated circuit; Oxidation; Electroless plating; X-ray photoelectron spectra
• ISSN: 0167-9317; 1873-5568
• DOI: 10.1016/j.mee.2007.07.017

In this study, W and tungsten nitride films were fabricated by reactive sputtering in a N 2/Ar atmosphere, the native oxide growth on the surface of the tungsten nitride films was investigated by X-ray photoelectron spectroscopy (XPS). It was found that tungsten nitride films were the mixture of W and W 2N sputtered in atmospheres of 3 mTorr argon and at the N 2 partial pressure from 0.1 to 2.0 mTorr. The ratio of W and W 2N in films was changed with the nitrogen partial pressure in sputtered chamber. Surface oxidations of the W film and tungsten nitride films advanced with time. Electrochemical measurement shows that all reduction–oxidation (redox) potentials of tungsten and tungsten nitrides were lower than that of copper film in electroless copper solution. And so, electroless-plated copper could be deposited on the surface of tungsten nitride films when the substrates were immersed into electroless copper plating solution without any pretreatment. Tungsten nitride films are appropriate for ULSI Cu interconnections using electroless Cu deposition.