Electrical characteristics of SiGe pMOSFET devices with tantalum or titanium oxide higher-k dielectric stack

Metal oxide semiconductor field effect transistors (MOSFET) with SiGe channel and higher-k gate dielectric are studied in this work. Samples with TaON/HfO2 or TiON/HfO2 stacks show larger drain current, better transconductance, and smaller subthreshold swing than that with single HfO2 layer. In addition, the reliability for SiGe pMOSFET device is clearly improved with TaON/HfO2 stacks in terms of degradation of Gm and Vth after hot-carrier stress. The integration of SiGe channel with TaON higher-k dielectric is useful for high performance pMOSFETs.

► TaON/HfO2 stacked devices show better electrical characteristics than HfO2 one.
► Higher-k stacked device shows high hole mobility with employing SiGe channel.
► Gm and Vth shifts after stress for TaON stacked devices are within common reliability criterion.
► The detrimental influence of Ti diffusion on reliability of MOSFET is clear.
► TaON/HfO2 higher-k dielectric stack is promising for MOSFETs with SiGe channel.