Ab initio modeling results including the formation, migration, and activation energies for B diffusion through bulk and grain boundaries in polycrystalline HfO2 films were presented. Modeling results clearly indicated that B could penetrate through a 4nm HfO2 film via grain boundary diffusion, but not by bulk diffusion. Secondary ion mass spectroscopy analysis of B concentration profiles for polysilicon/HfO2/Si gate stacks after different anneals showed double B peaks at the interfaces and thus confirmed the modeling prediction.

Theoretical and Experimental Investigation of Boron Diffusion in Polycrystalline HfO2 Films. C.L.Liu, Z.X.Jiang, R.I.Hegde, D.D.Sieloff, R.S.Rai, D.C.Gilmer, C.C.Hobbs, P.J.Tobin, S.Lu: Applied Physics Letters, 2002, 81[8], 1441-3