薄膜晶体管中高性能HfO_2的低温制备研究

Fabrication of Thin Film Transistor with High Performance HfO_2 Coatings Synthesized at Low Temperature

采用电子束蒸镀在ITO上沉积Hf O2,研究了不同退火工艺对其电学性能的影响。当450℃时O2退火,Hf O2的漏电迅速增加,通过X射线衍射发现Hf O2有单斜相等结晶生成。450℃下N2退火,Hf O2结构则没有明显晶体和晶界结构,且N2气氛退火的Hf O2漏电约为O2气氛退火的1/10。

The Hf O_2 coating,synthesized by electron beam evaporation and annealed in O_2 or N_2atmosphere on the ITO-coated glass substrate was used as the grid dielectric material in fabrication of thin film transistor（ TFT）. The influence of the thickness and annealing atmosphere,on the phase-structures and electrical properties of the Hf O2 coatings was investigated with X-ray diffraction. The results show that the annealing strongly affects the microstructures and electrical properties. For example,annealed at 450 ℃ for 30 min in O_2,the leakage current sharply increased,possibly because the boundaries between the monoclinic,cubic and orthorhombic-phased grains resulted in the formation of leakage channel. In contrast,an annealing in N_2 inhabited such grain-boundary formation and crystallization,reducing the leakage current by more than 10 times. We suggest that the Hf O_2 film be a promising TFT grid material because of its high dielectric constant and low leakage current.