Effect of Linear Aliphatic Polyamines on Copper Removal Rate in Chemical Mechanical Planarization (CMP)

Abstract

The role of homologous linear aliphatic polyamines as additives in Cu CMP slurries was investigated. We show that, in addition to forming stable complexes with copper ions in solution, the polyamines also interact with the copper metal preventing its corrosion. The latter effect increases with the polyamine chain length making the superior members of the homologues series effective passivating agents. A mechanism that explains the trend in the anticorrosion activity of polyamines is proposed. © The Author(s) In-depth investigation of Cu-CMP has gained recently significant impetus in response to increasingly sophisticated applications. From the chemistry view point, the removal of copper is the result of two consecutive processes: the oxidation of the metal and the complexation of copper ions to facilitate their transport in the liquid phase. Hydrogen peroxide (H 2 O 2 ) is the oxidant most widely used to 'extract' electrons from copper. [1][2][3][4][5][6] The resulting ions easily hydrolyze at neutral and alkaline pH forming insoluble oxide films that hinder the oxidation. The role of complexing agents is to dissolve the oxides and ensure the access of H 2 O 2 molecules to the metal. In their presence, the oxidation can continue indefinitely but its rate is often uncontrollable. The corrosion inhibitors (passivating agents) added to the slurry allow the 'fine-tuning' of Cu dissolution. The copper passivation can be caused by an adherent insoluble film on the copper surface or the chemisorption of species capable of preventing the reaction with the oxidizer. The corrosion inhibition provided by benzotriazole (BTA) is an example of the first mechanism. It is widely accepted that its effectiveness is due to a strongly attached insoluble multi-molecular layer on the copper surface, the precise structure of which is still being debated. 1,[7][8][9][10][11][12] In the case of the chemisorption mechanism, the extent of the stability gained by copper depends on the strength of the metal-ligand interactions as well as on how the ligand molecule is attached to the surface (conformational factor). Starting from the hypothesis that in the case of linear aliphatic polyamines the latter aspect varies widely, we initiated a systematic investigation of their passivating action in the corrosion of copper. In doing so, we fill a gap in Cu-CMP research as the study of linear aliphatic polyamines was limited until now to the first member of the series (ethylenediamine, EDA) and only in its role as complexing agent. 13-17 ExperimentalThe aqueous polishing slurries were freshly prepared by dissolving ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA) and pentaethylenehexamine (PEHA) in deionized water followed by the addition (if needed) of H 2 O 2 . In all cases the pH was adjusted at 9.0 ± 0.1.Dynamic polishing experiments were carried out for 1 min on an Allied benchtop unit using an IC 1000 polyurathane pad under a down force of 58 LbF. The platen and carrier rotation sp...

Post-CMP Cleaning Solutions for the Removal of Organic Contaminants with Reduced Galvanic Corrosion at Copper/Cobalt Interface for Advanced Cu Interconnect Applications

“…51,52 Gorantla et al and Karunaratne et al found that the polishing slurries consisting of En at alkaline pH were able to enhance the removal rate of Cu films. 53,54 Keeping these results in mind, we chose citric acid, glycine, EDTA, and En as the chelating agents in the cleaning solutions for our experiments.…”

Effect of Chelating Agent and Ammonium Dodecyl Sulfate on the Interfacial Behavior of Copper CMP for GLSI

“…Dinusha P. et al 18 investigated the effect of linear aliphatic polyamines on copper removal rate in chemical mechanical planarization. It was revealed that the corrosion of copper can be controlled by changing the molecular weight of polyamine.…”

Effect of Complexing Agent Choices on Dishing Control Level and the Shelf Life in Copper CMP Slurry

“…17 Dinusha P. Karunaratne et al investigated the role of homologous linear aliphatic polyamines on copper removal rate. 18 They found that the corrosion of copper could be controlled by simply changing the molecular weight of the aliphatic polyamine. When the ultra-low-k materials are introduced as interlevel dielectrics, the copper slurry relies heavily on the z E-mail: luanyz1988@126.com chemical route by selecting special complexing agents to achieve a low down-pressure at a low concentration of BTA.…”