Cubic-Structured HfO2 With Optimized Doping of Lanthanum for Higher Dielectric Constant

It is demonstrated that HfO2 films can have much higher dielectric-constant values than the usual reported value of 20-24 by optimized incorporation of lanthanurn element and crystallization to cubic structure. When HfO2 with 8% La is crystallized into cubic structure, the film exhibits the kappa value of similar to 38 which is the highest among ever reported HfO2-based high-kappa dielectrics. The increased kappa value of HfO2 with 8% La enables the leakage current to be reduced more than one order of magnitude lower, compared to amorphous-phase HfO2 under the same electric field. The dependence of film thickness and annealing temperature on the cubic crystallization is also reported.