Study on the Adsorption and Inhibition Mechanism of 1,2,4-Triazole on Copper Surface in Copper Interconnection CMP

Abstract

The chemical mechanical planarization (CMP) has been a key technology in the copper interconnection process of dual damascene. Corrosion inhibitors are often used as an important component in CMP slurry to protect the copper from corrosion at the recess to obtain a high or low selectivity ratio for copper removal rate. 1,2,4-triazole (TAZ) has been recently reported to be a promising inhibitor that can replace benzotriazole(BTA). It has been proved that 0.045M TAZ can achieve the same chemical protection as 0.002M benzotriazole on copper surface. The present study investigates the adsorption passivation reaction between different treated copper samples and a representative corrosion inhibitor TAZ. The three kinds of copper samples treated with as received, citric acid and citric acid + H2O2 were soaked in TAZ solution of 0.05M. The change of adsorption characteristics of copper surface was examined by contact angle measuring instrument, the formation of Cu-1,2,4-triazole was quantified by electrochemical impedance spectroscopy (EIS) and the change of chemical elements on copper surface was analyzed by X-ray photoelectron spectroscopy (XPS). Based on the experimental results, it can be concluded that TAZ can react on the surface of copper to form a weak passivation film of Cu-1,2,4-triazole, and TAZ is preferentially adsorbed on the copper surface treated with citric acid+H2O2.

Synergistic Action Mechanism and Effect of Ammonium Dodecyl Sulfate and 1,2,4-triazole in Alkaline Slurry on Step Height Reduction for Cu CMP

“…17,20 Cu ions can bond with N atom on the TAZ ring in alkaline condition to form protective film, which belongs to chemisorption. 11,21,22 In the ADS + TAZ mixed inhibitors system, the surfactant film is not likely to be entirely compact, which indicates there are some open regions on the Cu surface. It also indicates why the rate is still fast only in the presence of ADS.…”

“…However, in the presence of BTA, fragile Cu interconnection structures can be easily damaged. 11 Meanwhile, BTA reacts with Cu ions to form a thick Cu-BTA complex film, which is stable and difficult to be desorbed, and the residual BTA makes the surface highly hydrophobic in nature, which leads to the generation of watermarks and also poor adhesion of the stacking layers. [11][12][13] Hence, TAZ was chosen as an inhibitor.…”

“…11 Meanwhile, BTA reacts with Cu ions to form a thick Cu-BTA complex film, which is stable and difficult to be desorbed, and the residual BTA makes the surface highly hydrophobic in nature, which leads to the generation of watermarks and also poor adhesion of the stacking layers. [11][12][13] Hence, TAZ was chosen as an inhibitor. Qi Wang et al 11 proposed that the adsorption binding energy between TAZ and divalent Cu was higher than that of monovalent Cu, and the adsorption sites of coordination unsaturated Cu and TAZ molecules were more attractive to each other.…”

“…[11][12][13] Hence, TAZ was chosen as an inhibitor. Qi Wang et al 11 proposed that the adsorption binding energy between TAZ and divalent Cu was higher than that of monovalent Cu, and the adsorption sites of coordination unsaturated Cu and TAZ molecules were more attractive to each other. Liang Jiang et al 6 proposed that in the case of low abrasive concentration, TAZ had a stronger inhibitory effect than BTA, and the Cu-TAZ passivation film is also relatively thin and readily removable, leaving a hydrophilic Cu surface after cleaning.…”

Synergistic Effect of Pad “Macroporous-Reactors” on Passivation Mechanisms to Modulate Cu Chemical Mechanical Planarization (CMP) Performance

“…corrosive/abrasive). 2,6,[19][20][21][22][23][24] While there is large agreement within the community that benzotriazole (BTA) is a first-rate inhibitor, only a small sub-set of work has been done to probe its mechanism of complexation and how structural changes to the inhibitor alter its ability to limit corrosion. 14,25,26 Furthermore, the type of pad used (i.e.…”