Breakdown fields and conduction mechanisms in thin Ta_2O_5 layers on Si for high density DRAMs

摘要

The conduction mechanism and the microstructure of rf sputtered Ta_2O_5 on Si, before and after oxygen annealing at high temperatures (873, 1123 K; 30 min) have been investigated. The as-deposited at 873 K layers are amorphous whereas crystalline Ta_2O_5 (orthorhombic β-Ta_2O_5 phase) was obtained after O_2 treatment at 1123 K. The results (electrical, X-ray diffraction, transmission electron microscopy) reveal the formation of an interfacial ultrathin SiO_2 layer under all technological regimes used. The higher (493 K) substrate temperature during deposition stimulates The formation of amorphous rather than crystalline SiO_2.