Leveling effects of copper electrolytes with hybrid-mode additives

Abstract

100 nm vias were completely filled with copper for interconnect applications using an electrolyte in the presence of polyethylene glycols ͑PEG͒ and a hybrid-mode additive, benzotriazole ͑BTA͒. Electrochemical analyses indicated that BTA with a higher concentration inhibited the copper deposition rate, whereas BTA with a lower concentration accelerated the copper deposition rate. This electrolyte thus generated an enhanced deposition gradient within a gap because the PEG molecules and the high concentration of BTA, adsorbed at the opening of the gap, inhibited the deposition. Meanwhile, a little BTA diffused into the inner part of the gap and thus accelerated the deposition of copper. Therefore, this two-component ͑PEG and BTA͒ additive electrolyte had the capacity of a three-additive bath ͑accelerators, suppressors, and levelers͒.

Copper electrodeposition in sulphate solutions in the presence of benzotriazole

“…Previous studies have focused on either the influence of BTA on deposit properties during copper electrodeposition [8,[11][12][13][14][15][16][17][18][19][21][22][23][24] or the adsorption of BTA on copper during Cu 2+ reduction [20,21,32,36]. However, none of these studies considered the influence of BTA during pulse plating.…”

“…Although the influence of Cl ) and BTA together on DC copper plating has been studied [20,22,24,36,37], no investigations of their effects during pulse plating have been reported to the best of our knowledge. Consequently, we are also concerned with a comparison of deposit morphology obtained by pulse and DC plating in the presence of the two additives.…”

“…Among the common additives used for copper electrodeposition in sulphate plating baths is benzotriazole (BTA) [8,[11][12][13][14][15][16][17][18][19][20][21][22][23][24], which is also an effective corrosion inhibitor for copper and its alloys by forming a protective chemisorbed film [25][26][27][28][29][30][31][32][33][34].…”

Leveling of Superfilled Damascene Cu Film Using Two-Step Electrodeposition

“…21 There is also an investigation about Cu filling using BTA as a hybrid-mode additive showing an accelerating effect at low concentrations and an inhibiting effect at high concentrations. 22 Due to its strong adsorption ability on the Cu surface and strong suppressing effects on the electrodeposition kinetics, BTA is considered as a prime candidate for a leveler. However, interaction of BTA with an accelerator and manifestation of the suppressing effect even in the presence of accelerator has been little investigated.…”