Time-dependent diffusivity of boron in silicon oxide and oxynitride

The diffusivities of boron in silicon oxide and oxynitride have been determined from secondary ion mass spectroscopy measurements of annealed metal-oxide-silicon structures. The results clearly show a decrease in diffusivity with increasing anneal time which is approximately exponential in form. This effect implies a similar time dependence in the concentration of a secondary species, such as hydrogen, or a defect within the dielectric, which promotes diffusion even in a nominally pure oxide.