The diffusivities of boron in silicon oxide and oxynitride have been determ
ined from secondary ion mass spectroscopy measurements of annealed metal-ox
ide-silicon structures. The results clearly show a decrease in diffusivity
with increasing anneal time which is approximately exponential in form. Thi
s effect implies a similar time dependence in the concentration of a second
ary species, such as hydrogen, or a defect within the dielectric, which pro
motes diffusion even in a nominally pure oxide. (C) 1999 American Institute
of Physics. [S0003-6951(99)03207-6].