The diffusion of phosphorus into thin SiC>2 films on Si was studied to assess the significance of an anomalous, rapid diffusion mode. Diffusions were performed over a wide range of temperature and time using neutron-activated, red phosphorus diffusion sources. It was found that diffusion anneals in P vapors catalyzed a localized amorphous-to-crystalline transformation in the initially amorphous films, creating rapid diffusion paths at the interfaces between the crystalline islands and the surrounding amorphous matrix. The shape of the penetration profiles confirmed that interfaces contributed to the flux of P through the film. Both rapid and normal diffusion coefficients were determined and are discussed. Crystallization with subsequent rapid diffusion may be a contributing factor to the failure of SiO2 diffusion masks.
- diffusion mask. a-crystobalite
- interface diffusion
- network diffusion