Factors Influencing Characteristics of Hafnium Based High-K Dielectrics

Abstract

In this paper, factors influencing characteristics of thin hafnium based dielectrics are investigated. Impact of deposition techniques on film characteristics is studied by comparing HfO2 films deposited by atomic layer deposition (ALD) and metal organic chemical vapor deposition (MOCVD). Impact of precursor choice on HfO2 material and electrical properties is revealed by comparing a hafnium tetrachloride (HfCl4)-water process and a tetrakis[ethylmethylaminohafnium] (TEMAHf)-ozone process. In addition to deposition technique and precursor choice, thin hafnium-based film properties are also impacted by materials in contact with the dielectric. Significant differences in physical and electrical properties were observed when HfO2 is annealed at a high temperature with and without a metal (TiN) capping layer. Finally, the role of additives or impurities on characteristics of hafnium-based films was studied by modulating the amount of ZrO2 content in HfO2 from 0.2% to 98%. Improvements on the properties of HfO2 with ZrO2 addition are discussed.