Role of 1,2,4-Triazole in Co/Cu Removal Rate Selectivity and Galvanic Corrosion during Barrier CMP

Abstract

Removal rate selectivity control and galvanic corrosion reduction between cobalt (Co) and copper (Cu) are two challenges during cobalt barrier chemical mechanical polishing process in copper interconnects. This paper focuses on the investigation of a typical inhibitor 1,2,4-triazole on Co/Cu removal rate selectivity and galvanic corrosion under alkaline conditions. It is revealed that the selectivity of cobalt removal to copper is improved by accelerating the cobalt removal at low 1,2,4-triazole concentration, and then the removal rate of both metals is inhibited as 1,2,4-triazole further increased at 0.5 wt% colloidal silica concentration. Based on results, the inhibition action of 1,2,4-triazole was proposed. 1,2,4-TAH and 1,2,4-TA − species exist and account for at pH 10, then physical adsorption between 1,2,4-TAH and copper or cobalt atom via N4 site and chemical adsorption between 1,2,4-TA − and metal cation by sharing nitrogen atoms with a free electron pair in triazole ring occur on the two metals surface, resulting in copper and cobalt inhibited. The corrosion inhibition efficiency (IE) and corrosion potential difference ( E) was obtained from the potentiodynamic polarization plots. The results indicate that 1,2,4-triazole is an effective inhibitor both for chemical and galvanic corrosion.

A review on chemical and mechanical phenomena at the wafer interface during chemical mechanical planarization

“…Azole derivatives such as BTA and TAZ have been widely used as corrosion inhibitors for metal films during polishing [Fig. 5(c)] [101,102,103]. BTA can be adsorbed onto a Cu film by the coordination of the lone-pair electrons of the N atoms in BTA [Fig.…”

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.…”

Controlling the Removal Rate Selectivity of Ruthenium to Copper during CMP by Using Guanidine Carbonate and 1, 2, 4-Triazole

“…11 shows the molecular structure of BTA and TAZ, ∼NH 2 structure is contained in them, and TAZ − easy to form due to the lower energy of H-N bond and cleavage. 28 Therefore, the electrostatic attraction between the copper oxide [isoelectric point, IEP = 9.8] 29 with a positive charge and the deprotonated TAZ − supported the formation of Cu-TAZ complexes. However, it is worth noting that when TAZ is in lower concentration, the removal rate of Cu is even higher than that of no inhibitor (Fig.…”