Formation of hafnium-aluminum-oxide gate dielectric using single cocktail liquid source in MOCVD process

Abstract

We demonstrate that a high quality metal organic chemical vapor deposition (MOCVD) HfAlxOy (hereafter HfAlO) dielectric film can successfully be deposited with a wide range of composition controllability between HfO2 and Al2O3 in HfAlO using a single cocktail liquid source HfAl(MMP)2 (OiPr)5. A composition ratio between 45 to 90% of HfO2 in HfAlO is achieved by controlling deposition process parameters. The effect of the composition ratio between HfO2 and Al2O3 on the electrical properties of the film is also investigated. The HfAlO film with 90% HfO2 (10% Al2O3), which has minimum sacrifice of K value (around 19), shows a great improvement in thermal stability and significant reduction of interfacial layer growth during subsequent thermal processes, leading to the reduction in leakage current by around 2 orders of magnitude compared to pure HfO2 film. The HfAlO film also shows good compatibility with TaN metal gate electrode under high temperature annealing process.