Nitric Acid Oxidation of Si for the Tunneling Oxide Application on CoSi2 Nanocrystals Nonvolatile Memory

Abstract

In this work, nitric acid oxidation was studied to fabricate the tunneling oxide of nanocrystal memory devices. SiO2 about 4 nm thick was formed through oxidizing the sputtered Si film by immersing in nitric acid solution (HNO3:H2O=1:10) for 60 s. After oxide formation, a rapid thermal annealing process set at 700 degrees C for 30 s was used to improve oxide quality. In addition, the formed SiO2 film was analyzed by X-ray photoelectron, capacitance-voltage, and current density-voltage measurements to study the process of the nitric acid oxidation. After the investigation of the nitric acid oxidized SiO2, a 6 nm thick cobalt silicide thin film was deposited and aggregated on the formed SiO2 layer as the charge-trapping layer. The cobalt silicide nanocrystal memory device showed an obvious memory effect and good reliability, which confirms that the nitric acid oxidation method has potential for memory application.