Effects of glass-forming elements (Si, Al, and Bi) on the characteristics of Zr-based oxide films

We investigate the effects of glass-forming elements, such as Si, Al, and Bi, on the crystallization and the electrical properties of Zr-based oxide films for alternative gate dielectric applications. It is observed that the crystallization temperature increases and the dielectric constants are reduced as the amount of glass-forming additive is increased. Addition of Si results in the most stable amorphous phase with a significant reduction of the dielectric constant. When the atomic ratio of Zr over (Si + Zr) is about 0.45 and the film is annealed at 950 .deg. C for 1min, no crystallization behaviors are noticed and the dielectric constant is 12. On the other hand, substitution of Bi for Zr keeps the dielectric constant at 20 while it reduces the crystallization temperature to lower than 600 .deg. C. Addition of Al causes a moderate improvement in the crystallization behavior with a small sacrifice in the dielectric constant. Amorphous films of ZrXAl1-XOy (X = 0.45) remain amorphous up to 800 .deg. C anneals and have a dielectric constant of 15.