Physical and Electrical Characterization of Fluorine Plasma Treated Hafnium Oxide Film for High Density Metal-Insulator-Metal Capacitors

摘要

The influence of CF4 plasma-treatment (PT) on atomic-layer-deposited HfO_2 dielectric has been investigated for high density metal-insulator-metal capacitor applications. X-ray photoelectron spectroscopy analyses reveal that the PT leads to incorporation of fluorine atoms into the HfO_2 film by means of forming new chemical bonds of F-Hf-O near the surface. The resulting capacitance density increases up to 10.17fF/μm~2 with increasing the PT time to 10min, and the α decreases by 50ppm/V~2 after the PTs. Further, the PT time of 5min results in a decrease by around one order of magnitude in the leakage current density at -3V, i.e., 3.5×10~(-8) A/cm~2, compared to no PT. The above improvements can be attributed to F-passivation of oxygen vacancies at the interface of HfO_2/Al as well as a slight increase in the surface roughness of HfO_2 due to the PT.