Methodology of ALD HfO₂ High-κ Gate Dielectric Optimization by Cyclic Depositions and Anneals

This paper presents the optimization of HfO2 high-κ gate dielectrics by utilizing cyclic depositions and anneals during atomic layer deposition (ALD). An order of magnitude reduction in gate leakage is obtained by tuning the anneal temperature, duration and sequence in the ALD. The films are also seen to have three to four times reduction in carbon content. These optimized films are moreover observed to be densified without compromising equivalent oxide thickness (EOT), carrier mobility and threshold voltage. Further electrical characterization supports that there is a suppression of trap assisted tunneling with the optimized ALD process by revealing a stronger temperature dependence on the annealed samples as opposed to the conventional ALD process.