Binary HfO_2:SiO_2 Used as High-k Gate Oxide in Combinatorial Material Library Method

摘要

Hafnium silicates (HfO_2:SiO_2, HSO) have recently attracted much interest in the fields of fundamental science and technology because they have high dielectric constant and low leakage current. The structure and properties of HSO gate oxides were studied using a combinatorial continuous-compositional-spread method. HSO material libraries were synthesized on a 4-inch wafer at room temperature and at 200℃ using a custom-built radio-frequency (RF) sputtering system. The electrical properties of HSO material libraries were measured using metal-oxide-semiconductor structure. X-ray diffraction (XRD) was utilized to characterize the structure and compositions of HSO material libraries. The effects of sputtering conditions on the properties of the HSO gate oxides were investigated. The dielectrics constants (ε_r) of HSO material libraries treated with rapid thermal annealing (600℃/lmin/N_2) were in the range 5～23, as determined by C-V measurement, and the dielectric constant was observed to increase with HfO_2 content. The Ⅰ-Ⅴ relations of the HSO material libraries indicate that the leakage current decreases as the amount of Si in the HSO films increases. The structural characteristics of HSO films with RTA treatment (1000℃/10sec/N_2) varied from the amorphous to the crystalline state (tetragonal and monoclinic phase), according to the composition of material libraries. The correlation among the electrical properties, the composition and the crystal structure of the HSO films is discussed.