We have demonstrated the method of threshold voltage (VT) adjustment by controlling Ge content in the SiGe p-channel of N1 complementary field-effect transistor (CFET) for conquering the work function metal (WFM) filling issue on highly scaled MOSFET. Single WFM shared gate N1 CFET was used to study and emphasize the VT tunability of the proposed Ge content method. The result reveals that the Ge mole fraction influences VTP of 5 mV/Ge%, and a close result can also be obtained from the energy band configuration of Si1-xGex. Additionally, the single WFM shared gate N1 CFET inverter with VT adjusted by the Ge content method presents a well-designed voltage transfer curve, and its inverter transient response is also presented. Furthermore, the designed CFET inverter is used to construct a well-behaved 6T-SRAM with a large SNM of ~120 mV at VDD of 0.5 V.
Keywords: CMOS inverter; SiGe; complementary FET (CFET); technology computer-aided design (TCAD); threshold voltage adjustment.