Wang et al. Nanoscale Research Letters 2011, 6:483 http://www.nanoscalereslett.com/content/6/1/483 N A N O E X P R E S S Open Access Self-assembled monolayer of designed and synthesized triazinedithiolsilane molecule as interfacial adhesion enhancer for integrated circuit Fang Wang*, Yanni Li, Yabin Wang and Zhuo Cao Abstract Self-assembled monolayer (SAM) with tunable surface chemistry and smooth surface provides an approach to adhesion improvement and suppressing deleterious chemical interactions. Here, we demonstrate the SAM comprising of designed and synthesized 6-(3-triethoxysilylpropyl)amino-1,3,5-triazine-2,4-dithiol molecule, which can enhance interfacial adhesion to inhibit copper diffusion used in device metallization. The formation of the triazinedithiolsilane SAM is confirmed by X-ray photoelectron spectroscopy. The adhesion strength between SAM- coated substrate and electroless deposition copper film was up to 13.8 MPa. The design strategy of triazinedithiolsilane molecule is expected to open up the possibilities for replacing traditional organosilane to be applied in microelectronic industry. Keywords: adhesion, copper, diffusion barrier, self-assembled monolayer, surface chemistry Introduction Isolating individual components of nanoscale architectures comprised of thin films or nanostructures is a critical chal- lenge in micro- and nanoscale device fabrication [1]. One important example that illustrates this challenge could be seen in Cu-interconnected sub-100-nm device structures, which require less than 5-nm-thick interfacial layers to inhibit Cu diffusion into adjacent dielectrics [2]. Conven- tional interfacial barrier layers such as TaN, Ta, Ti, TiN, or W have already been optimized in microelectronic applications. However, such “thick” layers are not suitable for micro- and nanoscale device fabrication, and the above materials cannot form uniform and continuous film below 5 nm in thickness [3]. The barrier layer thickness must be minimized while maintaining high-performance diffusion barrier properties and good adhesion strength with neigh- boring layers [4]. Another significant example is seen in the adhesion between copper and substrate in printed circuit board technology. An alternative to the above interfacial layer is the organic self-assembled monolayer (SAM) [5] with sub- nanometer dimensions. The SAM [6,7] composed of * Correspondence: wangfang4070@nwsuaf.edu.cn College of Science, Northwest Agriculture and Forest University, Xi Nong Road No. 22, Yangling, Shaanxi 712100, China short aliphatic chains with desired terminal function groups has been investigated by modifying surface prop- erties for the above requirement. The selectivity and adhesion strength between the function group of SAM and the substrate impact the film packing density and thermal stability, and the chain length also has influence on the packing density and order. In recent years, G. Ramanath has reported the technique of fabricating SAM with the organosilanes as Cu diffusion barrier layer, and interfacial adhesion in microelectronics devices [2,8-12]. The results showed that the SAM inhibited Cu diffusion into substrate interface and enhanced the inter- facial adhesion to increase the device lifetime [8,13]. This technique has two advantages: (a) a strong interfacial bonding which can immobilize Cu, and (b) the creation of a vacuum-like potential barrier between Cu and the dielectric layer to inhibit Cu ionization and transport [14]. The former can be achieved through strong, local chemical interaction by choosing appropriate terminal groups, and the latter can be accomplished by using SAM with suitable chain length or the introduction of aromatic group. This technique offers the potential for tailoring effective barriers with decreased thickness. The organosilane molecules used to fabricate SAM as functional interfacial layer have been widely investigated. © 2011 Wang et al; licensee Springer. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.