Effects of different oxidizers on the W-CMP performance

In this paper, we investigated the effect of oxidizers on tungsten-chemical mechanical polishing (W-CMP) process with three different kinds of oxidizers, such as H2O2, Fe(NO3)3, and KIO3. In order to compare the removal rate (RR) and within-wafer non-uniformity (WIWNU%) of three oxidizers, we used alumina (Al2O3)-based slurry of pH 4. According to the CMP tests, three oxidizers had a different removal mechanism on tungsten surface. Also, the microstructures of surface layer by atomic force microscopy (AFM) image were greatly influenced by the slurry chemical composition of oxidizers. The difference in removal rate and roughness of tungsten surface are believed to cause by modification of chemical reaction and mechanical behavior of Al2O3 abrasive particles in CMP slurry due to the adding of oxidizer.