Electrochimica Acta 52 (2007) 5150–5158 Potassium sorbate solutions as copper chemical mechanical planarization (CMP) based slurries Esta Abelev a,1 , Andrew Jonathan Smith b , Achim Walter Hassel b,2 , Yair Ein-Eli a,∗,2 a Department of Materials Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel b Max-Planck-Institut f¨ ur Eisenforschung, Max-Planck-Str. 1, D-40237 D¨ usseldorf, Germany Received 1 October 2006; received in revised form 6 February 2007; accepted 6 February 2007 Available online 13 February 2007 Abstract Copper depassivation and repassivation characteristics in potassium sorbate solutions, subsequent to mechanical abrading are reported. The identification of copper repassivation kinetics obtained subsequent to mechanical damage of copper protective films formed in sorbate based solutions is discussed. The repassivation rate of copper in sorbate based solutions was measured by means of a slurryjet system capable of measuring single particle impingments on microelectrodes. Copper repassivation rates measured by this slurryjet system in sulfate solutions containing 10 g L -1 potassium sorbate were found to be in the range of 0.5–1.5 ms. An increase in the potassium sorbate concentration leads to a decrease in copper repassivation time at potentials ranging from 200 to 600 mV Ag/AgCl . The impingement angle between the copper surface and a single abrasive particle has no impact on copper repassivation time nor peak current (I max ) values. XPS studies revealed that copper passivation in potassium based solution was due to the formation of a thin film which is constituted of: Cu 2 O, Cu(OH) 2 and Cu(II)-sorbate, while copper(II)- sorbate is mainly present at the top levels of the passive film. It is therefore recommended that the use of potassium sorbate as a passivating component in conjunction with the addition of strong oxidizing agents in chemical mechanical planarization (CMP) slurry design should be considered. © 2007 Elsevier Ltd. All rights reserved. Keywords: K-sorbate; CMP slurry; Copper depassivation and repassivation; Impingments; Spectroscopy 1. Introduction Copper is one of the most commonly used metals and has extensive applications in various industrial processes. In the last decade the role of copper in the microelectronic industry increased significantly. Copper is the metal of choice, replac- ing aluminum in integrated circuit (IC) interconnects, due to its higher specific conductivity and higher resistance to electromi- gration phenomena. Two electrochemical steps are recognized in Copper Dual Damascene technology; electroplating and chemical–mechanical planarization (CMP) [1]. The objective of CMP is to remove metal overburden from the top-end of the wafer leading to a global planarizing of the wafer surface [1–8]. ∗ Corresponding author. E-mail address: eineli@tx.technion.ac.il (Y. Ein-Eli). 1 Current address: Department of Chemistry, Princeton University, NJ, USA. 2 ISE active member. In order to optimize the copper CMP process, various chem- icals; oxidizing agents and inhibitors, have been suggested throughout the past years [1–26]. However, effective CMP can only be realized in solutions where metals and, in particular copper, are characterized through certain electrochemical char- acteristics: • rapid self passivation in the selected CMP slurry; • fast dissolution of exposed surface sites activated by direct contact with the pad and abrasive; • and finally, a rapid repassivation of the activated and exposed sites during further exposure [27]. The higher the electrochemical potential during the CMP pro- cess the better the results of the polishing will be, and therefore, the metal should be passive in a wide potential range. Thus, the necessary feature expected from the copper CMP slurry is to provide a rapid repassivation of the metal being polished in a wide potential range [7,8,27]. 0013-4686/$ – see front matter © 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.electacta.2007.02.010