The chemistry of additives in damascene copper plating

• Published in: IBM journal of research and development Vol. 49; no. 1; pp. 3 - 18
• Main Authors: Vereecken, P. M., Binstead, R. A., Deligianni, H., Andricacos, P. C.
• Format: Journal Article
• Language: English
• Published: Armonk International Business Machines Corporation 01.01.2005
• Subjects: Additives; Adsorption; Antiwear additives; Chemistry; Chloride; Copper; Electrolytes; Integrated circuits; Kinetics; Plating; Polyethylene glycol
• ISSN: 0018-8646; 0018-8646; 2151-8556
• DOI: 10.1147/rd.491.0003

Copper plating baths used for forming integrated circuit interconnects typically contain three or four component additive mixtures which facilitate the superfilling of via holes and trench lines during damascene plating. Extensive study over the last two decades has provided researchers with an understanding of the underlying mechanisms. The role of cuprous intermediates in the copper deposition reaction has long been acknowledged, but it is not yet fully understood. In this paper we describe the results of an electrochemical study of the interaction of the organic additives used with copper and copper ions in solution. It is shown that cuprous intermediates near the copper surface affect the overpotential and the kinetics of plating. The additives regulate the presence of cuprous species on the surface; levelers and suppressors inhibit Cu^sup +^ formation, whereas accelerating additives enhance Cu formation. Acceleration by the bis(sodiumsulfopropyl) disulfide (SPS) additive results from accumulation of cuprous complexes near the surface. Adsorbed cuprous thiolate [Cu(I)(S(CH^sub 2^)^sub 3^ SO^sub 3^H)^sub ad^] is formed through interaction of Cu^sup +^ ions and SPS rather than Cu^sup 2+^ and mercaptopropane sulfonic acid (MPS). [PUBLICATION ABSTRACT]