0013-4651/2014/161(9)/D381/00/$31.00 © The Electrochemical Society Copolymers of Imidazole and 1,4-Butandiol Diglycidyl Ether as an Efficient Suppressor Additive for Copper Electroplating

A multi-functionalized suppressor additive (IBDGE) for copper electroplating has been synthesized by co-polymerizing imidazole and 1,4-butanediol diglycidyl ether (BDGE). This new co-polymer contains ether, hydroxyl and imidazolium functionalities that are common functional groups in polyalkylene glycol (PAG) suppressors and state-of-the-art leveler additives such as the polymerizate of imidazole and epichlorohydrin (IMEP). Electrochemical studies reveal a synergistic suppression effect of these functional groups with respect to the copper electroplating. In addition, this polymer demonstrates a variety of interactions with bis-(sodium-sulfopropyl)-disulfide (SPS). Firstly, the ether part of the polymer interacts antagonistically with SPS which is typical for PAG polymers. Secondly, the IMEP-like part of the polymer interacts antagonistically or synergistically with the SPS similar to the IMEP polymer. Because of this, temporal instabilities appear in the galvanostatic copper plating in the form of oscillations in the potential/time transient measurements. An N-shaped negative differential resistance (N-NDR) is visible in polarization measurements. Overall, this new polymer acts as an efficient suppressor additive rather than as a leveler additive. Fill-experiments on Damascene test-structures demonstrate a successful superfill. The quality of the resulting copper deposit was analyzed on blanket wafers by Secondary Ion Mass Spectroscopy (SIMS) experiments. © 2014 The Electrochemical Society. [DOI: 10.1149/2.0111409jes] All rights reserved. Manuscript submitted March 7, 2014; revised manuscript received May 9, 2014. Published May 22, 2014. Copper electroplating certainly belongs to the most important pro