Effects of O₂- And N₂-plasma treatments on copper surface

In this work, we investigate the effects of oxygen (O₂) and nitrogen (N₂) plasma treatments on the copper surface of aluminum/amorphous silicon-nitricarbide/copper (Al/α-SiCN/Cu) metal-insulator-metal (MIM) capacitors with respect to their leakage current and breakdown field. It is found that both the O₂- and N ₂-plasma treatments have an adverse effect on the leakage current and breakdown field of MIM capacitors. The MIM capacitors with their Cu surfaces subjected to O₂- or N₂-plasma treatment exhibit a room-temperature leakage current density several orders of magnitude larger than that of the sample without plasma treatment at the same applied electric field. The room-temperature breakdown fields of the MIM capacitors with O₂- and N₂-plasma-treated Cu surfaces are 3.8 and 3.2MV/cm, respectively, while that of the control sample without plasma treatment is 7.8MV/cm. The increased leakage currents and degraded breakdown fields of the O₂- and N₂-plasma-treated samples are attributed, respectively, to the presence of metastable Cu-O oxide and Cu-N azide at the Cu surfaces.