SiGe channels for higher mobility CMOS devices

Silicon-Germanium (SiGe) is considered to substitute Silicon (Si) as channel material in future CMOS generations for its higher charge carrier mobility. In this work we investigate SiGe channels with low to medium Germanium content, even though the mobility is expected to be better with even more Germanium in the alloy. Low pressure chemical vapor deposition was used for SiGe deposition and a state of the art CMOS process including high-k dielectric and metal gate electrode was applied for fabrication of sub 50nm gate length devices. As expected from the SiGe channel conduction and valence band offset the threshold voltage of the devices is influenced. The gate stack was directly deposited onto the SiGe layer consisting of a chemically grown base oxide, Hafnium-based dielectric and Titanium nitride gate electrode. C-V and I-V measurements show comparable CET and leakage values for the high-k metal gate stack on Si and SiGe channels. The trap density at the channel dielectric interface was investigated using the charge pumping technique. The device characteristic of n- and p-MOSFETs with SiGe channels is compared to conventional Si channel devices to investigate the impact of SiGe channels on the device performance. Short channel mobility was extracted from RON-LG- as well as Gm,L-Method and match well to the observed device performance.