Charge trapping and dielectric relaxation in connection with breakdown of high-k gate dielectric stacks

Charge trapping/detrapping and dielectric polarization/relaxation of high- k dielectrics have been investigated. Relaxation behaviors of TiNSi O2 p-Si and TiNZr -doped Hf Ox Si O2 p-Si capacitors were studied with a ramp-relax method. The latter shows a relaxation current, which signifies the high- k dielectric integrity and disappears at breakdown, while the former does not. The breakdown sequences of TiNZr -doped Hf Ox Si O2 p-Si and AlHf -doped Ta Ox silicatep-Si were identified with relaxation current. For the former, the breakdown initiated at the interfacial Si O2 layer; for the latter, the breakdown starts from the Hf-doped Ta Ox layer. The breakdown sequence is explained with the material properties and thicknesses of individual layers. © 2006 American Institute of Physics.