Preparation of conductive HfN by post rapid thermal annealing-assisted MOCVD and its application to metal gate electrode

Conductive hafnium nitride (HfN) with negligible carbon impurity (<0.1 at.%) was chemically synthesized for the first time by post-rapid thermal annealing (PRTA)-assisted metal organic chemical vapor deposition (MOCVD) method. The thermodynamic instability of N-rich hafnium nitride (Hf₃N₄) phase, which is considered to be the dominant phase in CVD deposition of hafnium nitride, was utilized for pure and metallic HfN synthesis. By integrating the PRTA-HfN film into MOS capacitor, the electrical properties of the PRTA-HfN film as metal gate electrode were studied. Well behaved electrical characteristics such as about 4.9 eV of effective work function, low leakage current and large reduction in SiO₂ equivalent oxide thickness (EOT), which was attributed to the combination of physical thinning of SiO₂ and formation of high-κ interfacial layer, suggest the potential capability of PRTA-assisted MOCVD in chemically synthesizing HfN metal gate electrode for pMOS devices application.