Effect and mechanism analysis of sarcosine on the chemical mechanical polishing performance of copper film for GLSI

Abstract

With the decrease of integrated circuits feature size, chemical mechanical polishing (CMP) of copper (Cu) film for multilayer wiring is faced with new challenges. In order to reduce the step height of Cu film for cobalt-based Cu interconnect during CMP process, the selection of additives in the slurry is crucial. In this paper, sarcosine was used as an important additive in Cu slurry to improve the planarization properties. Through the polarization curves, dynamic polishing, static etching experiments and scanning electron microscopy (SEM) measurement, it was identified sarcosine as a complexing agent and trace functional reagent could improve the Cu planarization properties. Meanwhile, the adsorption and complexation mechanisms of sarcosine on Cu film surface were analyzed by electrochemical tests and X-ray photoelectron spectroscopy (XPS). The improvement of static etching and surface quality of Cu patterned wafers by sarcosine was verified by laser scanning confocal microscopy (LSCM). Low static etch rate (SER) (1658 Å/min), high removal rate (RR) (5091 Å/min), RR/SER of 3.07 and effective correction of the step height on Cu patterned wafers were achieved by the synergistic effect of sarcosine and benzotriazole (BTA). In this study, a green functional reagent for Cu film CMP in low-tech node multilayer wiring was provided, which is good practical application prospects.