A Novel Scaling Theory for Fully Depleted Omega-Gate MOSFETs Included With Equivalent Number of Gates

A novel scaling theory for fully depleted omega-gate (Omega G) MOSFETs, including rectangular-shaped Omega G (R Omega G) and cylindrical-shaped Omega G (C Omega G) MOSFETs, is presented. The natural length for the Omega G MOSFET is obtained by solving the equation of equivalent number of gates (ENG), where the ENG of the Omega G device working in the x-y-z space can be the sum of the ENGs for both the double-gate (DG) and single-gate transistors working in the y-z and x-z planes based on the perimeter-weighted-sum method. Numerical device simulation data for drain-induced-barrier-lowered effects (DIBL) were compared with the model to validate the theory. Among the R Omega G devices with the same perimeters, one with a square cross section and a large oxide-to-gate underlap coverage factor (OUCF) will show the worst immunity to the DIBL due to the largest natural length. For equivalent short-channel controlling capability, the R Omega G MOSFET with the OUCF = 0.7 illustrates an improvement of up to 25% in the minimum effective channel length L-min when compared with the DG MOSFET.