Device design guidelines for nano-scale MuGFETs

The short-channel properties of multi-gate SOI MOSFETs (MuGFETs) are studied by numerical simulation. The evolution of characteristics such as DIBL, subthreshold slope, and threshold voltage roll-off is analyzed as a function of channel length, silicon film or fin thickness, gate dielectric thickness and dielectric constant, and as a function of the radius of curvature of the corners. The notion of an equivalent gate number is introduced. This number ranges from 2 for a double-gate device to 4 in a gate-all-around transistor. The equivalent gate number can be used in general equations to predict the absence or presence of short-channel effects. As a general rule, increasing the equivalent gate number improves the short-channel behavior of the devices. Similarly, increasing the radius of curvature of the corners improves the control of the channel region by the gate.