HfO2/spacer-interface breakdown in HfO2 high-κ/poly-silicon gate stacks

The gate dielectric breakdown induced microstructral changes in HfO2 high-κ gate stacks are analyzed using high resolution transmission electron microscopy. A new failure mechanism along the interface of HfO2/spacer has been observed in HfO2 high-κ gate stacks. This breakdown which is more common in accumulation mode stressing conditions in HfO2 high-κ /poly-Si gate stacks has not been observed in oxynitride gate dielectrics. It is believed that this interfacial breakdown could be dependent on enhanced electric field at the source/drain extension regions and on the corner geometry of the high-/poly-Si gate stacks.