Relative roles of acetic acid, dodecyl sulfate and benzotriazole in chemical mechanical and electrochemical mechanical planarization of copper P.C. Goonetilleke, D. Roy * Department of Physics, Clarkson University, Potsdam, NY 13699-5820, USA Received 26 April 2007; accepted 5 October 2007 Available online 11 October 2007 Abstract The efficiency of chemical mechanical or electrochemical mechanical planarization (CMP or ECMP) carried out in the fabrication of integrated circuits is largely governed by the functional chemicals used in these processes. In this work, we study the individual and combined chemical and electrochemical effects of a selected set of such chemicals that can potentially support both CMP and ECMP of copper. These chemicals include acetic acid (HAc) as a complexing agent, H2O2 as an oxidizer, and ammonium dodecyl sulfate (ADS) as a dissolution inhibitor. Surface passivating effects of ADS under both CMP (open circuit) and ECMP (voltage activated) conditions are compared with those of a standard dissolution inhibitor for Cu, benzotriazole (BTAH), and the combined effects of a BTAH–ADS mixture also are explored. The experiments are performed in the absence of mechanical polishing using static and rotating Cu disc electrodes, and electro-dissolution of Cu for ECMP is activated using a voltage pulse modulation technique. A mechanism of surface reactions is proposed to describe the relative roles of HAc, H2O2, ADS and BTAH as electrolyte components for CMP and ECMP of Cu. # 2007 Elsevier B.V. All rights reserved. PACS : 68.08.-p; 68.43.-h; 81.20.-n; 81.65.-b; 82.45.Bb Keywords: CMP; Copper; Acetic acid; Surface composition; Semiconductor devices 1. Introduction Chemical mechanical planariztion (CMP) of copper is used in multilayer metallization during the fabrication of integrated circuits [1]. Eelectrochemical mechanical planarization (ECMP) is a promising extension of CMP for achieving abrasive-free low down-pressure planarization of Cu lines overlying mechanically fragile dielectrics [2–4]. In CMP, the Cu surface remains at its open circuit potential (OCP), where the chemical component of CMP (surfaced complex formation and dissolution) is dictated by thermodynamically allowed reactions [5–8]. In ECMP, the Cu sample is anodically polarized and surface layers of Cu are removed mostly through voltage (or current)-controlled electro-dissolution [5,9–12]. Mechanical abrasion, which generally plays an essential role in CMP is no longer necessary as a main route to material removal in ECMP. Typically mechanical abrasion in ECMP is used to remove thin passivating films of dissolution inhibitors from surface protrusions, and can be performed at a low down- pressure [2]. The chemical solutions used for ECMP may contain very little or no abrasive particles; this often helps to address certain issues of slurry handling as well as surface defects that are associated with abrasive-based CMP proce- dures [2,3]. A challenging task in CMP and ECMP is that of adequately designing the slurry-solutions or electrolytes necessary to support the chemical and/or electrochemical components of these processes. The solutions used in both CMP and ECMP typically include an oxidizer, a complexing agent, pH-adjusting additives, and dissolution inhibitor chemicals [1]. Surface reactions of these individual chemicals often are significantly changed in the presence of other co-additives in the solution. Thus, the combined performance of the chemical mixture is more important than those of the individual additives. Our www.elsevier.com/locate/apsusc Available online at www.sciencedirect.com Applied Surface Science 254 (2008) 2696–2707 * Corresponding author. Tel.: +1 315 268 6676; fax: +1 315 268 6610. E-mail address: samoy@clarkson.edu (D. Roy). 0169-4332/$ – see front matter # 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.apsusc.2007.10.005