Effect of interfacial fluorination on the electrical properties of the inter-poly high- k dielectrics

Abstract

In this paper, the reliabilities and insulating characteristics of the fluorinated aluminum oxide (Al 2O 3) and hafnium oxide (HfO 2) inter-poly dielectric (IPD) are studied. Interface fluorine passivation has been demonstrated in terminating dangling bonds and oxygen vacancies, reducing interfacial re-oxidation and smoothing interface roughness, and diminishing trap densities. Compared with the IPDs without fluorine incorporation, the results clearly indicate that fluorine incorporation process is effective to improve the insulating characteristics of both the Al 2O 3 and HfO 2 IPDs. Moreover, fluorine incorporation will also improve the dielectric quality of the interfacial layer. Although HfO 2 possesses higher dielectric constant to increase the gate coupling ratio, the results also demonstrate that fluorination of the Al 2O 3 dielectric is more effective to promote the IPD characteristics than fluorination of the HfO 2 dielectric. For future stack-gate flash memory application, the fluorinated Al 2O 3 IPD undoubtedly possesses higher potential to replace current ONO IPD than the fluorinated HfO 2 IPD due to superior insulating properties.