Electrical Properties of Ge pMOSFETs With Ultrathin EOT HfO2/AlOx/GeOx Gate-Stacks and NiGe Metal Source/Drain

The high performance Ge pMOSFETs have been realized with ultrathin HfO2/AlOx/GeOx/Ge gate-stacks fabricated by ozone postoxidation (OPO) and NiGe metal source/drain (S/D). It is found that OPO yields a reduction of interface traps and an improvement of dielectric strength for the HfO2/AlOx/GeOx/Ge gate-stacks. On the other hand, it is also confirmed that the NiGe metal S/D structure decreases the S/D parasitic resistance severely. As a result, the record high drive current has been realized under a comparable gate length for present Ge pMOSFET structure with the ultrathin equivalent oxide thickness HfO2/AlOx/GeOx/Ge gate-stack and the low parasitic resistance NiGe S/D.