ＴｉＮ表面へのＣｕおよびＰｄの置換析出挙動とその熱力学的考察

Abstract

Cu and Pd depositions onto a TiN layer with displacement reactions were investigated at three temperatures (25oC, 50oC, 70oC) using various fluoride solutions (pH1.6-5.2). Although both Pd and Cu were expected to be deposited onto TiN thermodynamically, Cu deposition did not take place unless the underlying Si layer was exposed to a fluoride solution, while Pd deposits were observed on the TiN layer under all conditions examined. This is because the reduction of protons is preferential to the Cu deposition on the TiN layer. The smallest Pd particles, with a diameter of about 50nm, were obtained at 70oC from a fluoride solution of pH5.2. The deposition rate and morphology of Pd were dependent on the pH and temperature of the solution. The dissolution of the TiN layer and the deposition of Pd were accelerated with decreasing pH, suggesting that, when the pH of the solution was low, most of the electrons released from the TiN were consumed for the reduction of protons.