Dependence of Chemical Composition Ratio on Electrical Properties of HfO₂-Al₂O₃Gate Dielectric

Abstract

The electrical properties of Hf–Al–O alloy films with various composition ratios prepared by atomic layer chemical vapor deposition (ALCVD) have been investigated to find the optimum composition ratio. The Hf–Al–O alloy with 67% composition of HfO2, (HfO2)0.67(Al2O3)0.33, shows a good thermal stability comparable to Al2O3 film and a lower amount of negative fixed charge similar to pure HfO2 film. A significant reduction in leakage current of 67%-HfO2 film compared to that of pure HfO2 film has been achieved, which is attributed to the improved thermal stability. From the results, it is found that the optimum composition ratio in Hf–Al–O alloy lies at around 60–70% of HfO2.