Abstract
As the scaling of silicon metal-oxide-semiconductor (MOSFET) approach to its limitation with the development of semiconductor industry, novel materials and innovative device structures need to be introduced in future. Ge is promising for a channel material in MOSFET, owing to its high hole and electron mobility. A high quality interface layer is necessary to improve characteristics on Ge-MOSFETs device. Hence, an accurate and quick measurement to detect interface trap density and distribution of bulk traps should be a valuable research topic. Several measurement techniques based on the charge pumping are proposed to detect trap density distributions. In the first study, interface layer with hydrogen treatment and microwave annealing Ge MOSFET devices obtain lower interface trap density and better interface layer quality than without one. The electrical characteristic have higher drive current, mobility, and lower off current, due to interface layer with hydrogen treatment can repair interface traps and microwave annealing can improve PN junction. On the other hand, hydrogen treatment can improve traps density less than depth about 0.8 nm and microwave annealing can obviously reduce traps density higher than depth about 1 nm from distribution profile of border traps density. In the second study, the interface trap density, bulk density and stress induced trap generation of Ge-pMOSFETs with ZrO2 and HfON gate dielectrics are extracted and compared by CP technique. Results show that ZrO2 device has higher interface trap density but lower bulk trap density than HfON device, which implies that ZrO2 device has inferior Ge/dielectric interface but high quality dielectric bulk. The improved reliability characteristics in ZrO2 device can be attributed to the low preexisting bulk trap density which suppresses charge trapping in the dielectric bulk. In the last study, charge pumping technique is used to detect interface and bulk trap distribution and stress induced trap generation of Ge-pMOSFETs with and without Hf buffer layer (HBL). The charge pumping technique confirm that device with HBL has lower interface and bulk traps density than device without, which show electrical characteristic can be improved. Results show that device with HBL has better performance from NBTI and PBTI reliability analysis because of it has higher quality of interface characteristics and dielectric bulk.