Multicomponent dielectrics for oxide TFT

In this work we present sputtered multicomponent dielectrics based on mixtures of HfO2 and SiO2. This way it is possible to get stable amorphous structure up to 800 degrees C, that does not happen for pure HfO2, for instance, that present a polycrystalline structure when deposited without any intentional substrate heating. Besides, also the band gap of the resulting films is increased when compared with pure HfO2 that theoretically is an advantage in getting a suitable band offset with the semiconductor layer on oxide TFTs. Concerning the electrical characterization, the leakage current on c-Si MIS structures is low as 10(-9) Acm(-2) at 10 V. The amorphous structure of the films also lead to better dielectric/semiconductor interfaces, as suggested by C-V characteristics on GIZO MIS structures, which do not present strong variation with frequency. On other hand, the dielectric constant decreases due to the incorporation of SiO2 and Al2O3. Further improvement on insulating and interface characteristics is achieved using multilayer stacks and substrate bias during deposition.