HfSiON Gate Dielectric for 45nm Node Low-Power Device

A 1.4 nm EOT stack film of HfSiON with interfacial oxide layer (IL) is demonstrated with excellent electrical characteristics and reliability for 45 nm node low-power technology. Mobility comparable to SiON is achieved along with adequate nMOS PBTI lifetime, TDDB lifetime, and breakdown voltage (VBD). For the first time, we report lower VBD for the HfSiON stack film despite of 3 orders gate leakage reduction compared to the same EOT SiON. It is attributed to IL breakdown in the proposed two-step breakdown mechanism. This possibly limits the scalability of such a stack film. On the other side, over-drivability of HfSiON with thick underlying oxide boosts input/output (I/O) device performance significantly.