Mechanically Induced Growth Rate Differential for Copper Layers Electroplated in Presence of Organic Additives

• Published in: Journal of the Electrochemical Society 2006-01, Vol.153 (10), p.C683-C688
• Main Authors: Basol, Bulent M, Durmus, Ayse, Wang, Tony, Erdemli, Serkan, Bogart, Jeff
• Format: Article
• Language: English
• ISSN: 0013-4651
• DOI: 10.1149/1.2223993

Electrochemical mechanical deposition (ECMD) planarizes copper films as they are plated on patterned wafer surfaces. The technique involves electrochemical deposition (BCD) and simultaneous sweeping of the cathode surface with a pad. Pad sweeping gives rise to a mechanically induced current suppression (MICS) phenomenon if plating is performed in electrolytes containing accelerator and suppressor additives as well as Cl(-) ions. In this work we studied the MICS phenomenon by partially sweeping blanket wafer surfaces with a small pad and investigating effects of the bath chemistry and wafer surface derivatization on the copper growth rates at the swept and unswept regions of the surface. It was found that, at a given suppressor concentration, copper growth rate differential between the two regions was reduced with increasing accelerator concentration in the bath. Derivatization of the wafer surface in an accelerator-containing solution followed by ECMD in a suppressor-containing bath gave the largest growth differential between the swept and unswept surface portions, suggesting high planarization efficiency. Adsorption-desorption kinetics of the organic additives used in this work were obtained under BCD conditions and found to support the proposed mechanism of MICS.