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

We demonstrate that a high quality metal organic chemical vapor deposition (MOCVD) HfAl_xO_y (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.