Reliability of HFO2/SIO2 dielectric with strain engineering using CESL stressor

We have investigated reliability characteristics for a high-k/metal gate MOSFET with strain engineering under constant voltage stress (CVS). Using contact edge stop layer (CESL), tensile and compressive strains are applied to the channel region. Since the compressive MOSFET has more hydrogen in the CESL, the MOSFET has lower reliability characteristics than others. Though the hydrogen can passivate dangling bonds in the high-k dielectric, the passivated bonds are easily broken by voltage stress, which cause degradation of high-k layer.