Evaluation of a Praseodymium Precursor for Atomic Layer Deposition of Oxide Dielectric Films

Amorphous PrOx based films were grown by atomic layer deposition in the temperature range 200-400 C from Pr [N(SiMe3)2]3 and H2O on n-Si(100) and borosilicate glass substrates. The films contained considerable amounts of residual hydrogen and residual or diffused silicon. The refractive indexes of the films varied between 1.76 and 1.87. Crystallization took place after annealing at 900-1000 C, and X-ray diffraction data indicated that the films were Pr9.33(SiO4)6O2. The effective permittivity of 70-100 nm thick films was in the range of 14-16. Annealing at 800 C in nitrogen increased the effective permittivity to 15.6 -21.0 and decreased the rechargeable trap density. Praseodymium silicate films may be applied after annealing as dielectric layers in capacitive structures