Effects of Electrolyte Formulas on Electrochemical Polish Planarization of Pure Copper

Abstract

Electrochemical polish technology could enhance the chemo-mechanical polishing efficiency of copper material. During the electrochemical polishing process, both the components and operation parameters of electrochemical polish solution are the key factors influencing planarization ability. This work measured the surface topography and roughness of copper material after mechanical polish by an atomic force microscope (AFM), and added glycerol in different ratios to the phosphoric acid (85 wt %), which was the main composition of experiment solution. Electrochemical polish was conducted within the potential action range in passivation area, and the surface topography and roughness of copper material after electrochemical polish was measured by AFM. The difference in surface topography of copper material after electrochemical polish was compared as well.The experiment indicated that after electrochemical polish in pure phosphoric acid for 50 sec, the surface roughness of copper material obviously decreased from 6.921nm (Ra) to 0.820nm (Ra), and the planarization was more obvious with the increase of electrochemical polish time. The above results could appear in different electrolyte formulas, indicating that electrochemical polish was a good processing method for copper material planarization. This work also proposed the effect of analyzing the electrochemical polish time on planarization through planarization efficiency. Based on the analysis, the planarization efficiency was decreased with the increase of electrochemical polish time, which indicated that longer electrochemical polish time did not yield better result. This work also found that the surface is not only flattened, but also glossed after electrochemical polish.