Effect of pH on CMP of VOx Thin Films for RRAM

Abstract

Resistive random access memory has attracted enormous attention as next generation high density nonvolatile memory for flash memory, due to its low voltage operation, high programming speed, and simple fabrication. And Chemical mechanical planarization technology of the novel memory materials is also the necessary work for its application in RRAM devices, especially for TiO2、 NiO and VOx films which are the focused RRAM materials recently. In this paper, CMP of VOx films was investigated firstly, and the effect of slurry pH on MRR and surface roughness was discussed. MRR results show that high polishing rates can be observed with low pH (acidic slurry) and high pH (alkaline slurry), which are more than 250 nm/min. However, lower surface roughness can be achieved only when alkaline slurry was used (0.12 nm vs 2.6 nm). In conclusion, the alkaline slurry with silica abrasives is the optimum candidate for CMP of VOx films.