Effects of Ar Plasma Treatment on the Properties of TaN/Ta Barrier for Copper Interconnects in Advanced 3D NAND Memory

The effects of Ar Plasma Treatment (APT) on the properties of Ta i.e. the transformation from high resistivity β-Ta to low resistivity α-Ta are manifested in this work. It is demonstrated that APT indeed promotes the formation of low resistivity α-Ta, as confirmed by the lower sheet resistance and more α-Ta in XRD patterns compared to the case without APT. XPS results reveal that the compositions of interfacial thin layer between Ta and TaN are different in two cases. The precession electron diffraction (PED) is used to determine the degree of crystalline in Ta. It is indicated directly that both α-Ta and β-Ta exist in the Ta layer. The Kelvin Resistor Chain (KRC) and Chain Contact Resistance (Chain RC) test results show that APT could also lead to remarkably reduced contact resistance.