Electrochemical corrosion effects and chemical mechanical polishing characteristics of tungsten film using mixed oxidizers

摘要

In this paper, the effects of mixed oxidizers on tungsten-chemical mechanical polishing (W-CMP) process were studied using three different kinds of oxidizers such as Fe(NO_3)_3, KIO_3 and H_2O_2. Moreover, the interaction between the tungsten film and the oxidizer was discussed by potentiodynamic polarization test, in order to compare the CMP performances and electrochemical behavior of the tungsten film as a function of mixed oxidizers. The potentiodynamic polarization results indicated that the corrosion current densities of the 5 wt% H_2O_2 and 5 wt% H_2O_2 + 5 wt% Fe(NO_3)_3 were higher than the other mixed oxidizers. Such an electrochemical corrosion effect implies that slurries with the highest removal rate have a high dissolution rate at lower pH. Therefore, we conclude that W-CMP performances are strongly dependent on the kind of oxidizers and the amounts of oxidizer additive.