Experimental and density functional theory study of benzohydroxamic acid as a corrosion inhibitor in chemical mechanical polishing of Co interconnects

Benzohydroxamic acid (BHA) was evaluated for the first time as a corrosion inhibitor for cobalt (Co) films polishing for interconnect application. The inhibition mechanism of the BHA on the Co surface was comprehensively studied. Langmuir adsorption isotherm model analysis showed that BHA had both chemisorption and physical adsorption on Co. The active sites of BHA and BHA- were analyzed by density functional theory (DFT). The calculation results show that the BHA molecule can be adsorbed vertically through the O1 atom, and parallel adsorbed through the benzene ring and the O1 atom. BHA- ions are adsorbed through O1 and O2 atoms. Through polishing experiments, surface topography measurements, static etch rate (SER) experiments, and electrochemical impedance spectroscopy (EIS) experiments, it was found that the BHA inhibitor film was easily removed mechanically, and the inhibition mechanism was proposed. During the chemical mechanical polishing (CMP) process, the material in the raised area of the wafer is mechanically removed, and the material in the recessed area is protected by an inhibitor film, which not only ensures the removal rate (RR) of Co, but also ensures the surface quality of the wafer.