Effect of synergetic inhibition of nonionic surfactant and benzotriazone for molybdenum in chemical mechanical polishing

Abstract

The continuous miniaturization of the feature size of integrated circuit makes it crucial to find proper barrier layer materials. With the properties of low resistivity (∼5.34 μΩ•cm) and good adhesion to Cu, Molybdenum (Mo) has become the most promising materials of the next generation of barrier layer. However, the studies on Mo chemical mechanical polishing (CMP) are limited. The problems of controlling Mo removal rate (RR) and improving its surface quality (Sq) are still unsolved. Here in, this paper focuses on minimizing Mo RR and Sq during CMP. Compared the inhibition effect of isooctanol polyoxyethylene ether (JFCE) and fatty alcohol polyoxyethylene ether (AEO-9) combine with benzotriazole (BTA) on Mo CMP, JFCE was selected as the most suitable surfactant. The addition of a small amount of JFCE can decrease Mo RR (from 308 Å/min to 176 Å/min) and static etching rate (SER) (from 201 Å/min to 50 Å/min) significantly. Furthermore, Mo Sq was also improved (from 6.34 nm to 0.255 nm) during CMP. The synergetic inhibition mechanism of JFCE and BTA was characterized by electrochemical test, contact angle test, adsorption isotherm, X-ray photoelectron spectroscopy, scanning electron microscopy and density functional theory. JFCE not only can change the proportion of Mo oxide, but also can complex with Mo chemically and physically, thus playing an inhibition effect on the convex and concave part of Mo surface. Furthermore, JFCE could keep the slurry stable at least for 7 days. This paper combined with experimental and theoretical methods to find a new Mo inhibitor, which has a promising effect to the study of barrier layer planarization of 14 nm sub-technology node.