Voltage Transfer Characteristic Matching by Different Nanosheet Layer Numbers of Vertically Stacked Junctionless CMOS Inverter for SoP/3D-ICs applications

For the first time, CMOS inverters with different numbers of vertically stacked junctionless (JL) nanosheets (NSs) are demonstrated. All fabrication steps were below 600 °C, and 8-nm thick poly-Si NSs with smooth surface roughness were formed by a dry etching process. Compared to single channel devices, stacked n/p-channel FETs exhibit higher on-current with low leakage current. Furthermore, a common-gate process was performed for the fabrication of CMOS inverters. By adjusting the NS layer numbers for n/pFETs, respectively, the voltage transfer characteristics (VTCs) of the CMOS inverter can be matched much better to reduce the noise margin due to on-current matching without area penalty. This work experimentally demonstrates a new configuration of CMOS inverters on stacked NSs, which is promising for System-on-Panel (SoP) and 3D-ICs applications.