Systematic Examination of Boron Diffusion Phenomenon in HfSiON High-k Gate Insulator

摘要

In this paper, boron diffusivities in HfSiON high-k gate dielectric films are systematically investigated for a wide range of the film composition. Boron diffusivities in HfSiON (1000℃) change from 3x10~(-17)cm~2/sec to 3x10~(-15)cm~2/sec according to the change in the chemical composition of the films. These diffusivity values are higher than that in SiON but lower than that in HfO_2. We found that higher Hf/(Hf+Si) results in great increase of diffusivities. On the other hand, higher nitrogen concentration in the film leads to the reduction in diffusivity, in the case of the same Hf/(Hf+Si). In addition, crystallization of HfSiON with the same chemical composition gives rise to an anomalous increase in difrusivities, indicating that the micro-crystallized film structure of HfSiON critically affects the microscopic mechanism of boron diffusion in this material.