Immunity to substrate effect in advanced ΩFET devices

We study the coupling effects in multiple gate SOI devices with Omega configuration, metal gate and HfO₂ dielectric. Electrical measurements together with numerical simulations show that the back gate influence is reduced for narrow devices due to a strong coupling between the different faces of the main gate. In spite of the full depletion of the transistor, this paper shows that threshold voltage, as well as subthreshold slope and DIBL+DIVSB are no longer dependent on the back gate bias. Devices are then immune to substrate effects. It is also shown for the first time that the conduction channels can be separated in wide ΩFETs using the back gate coupling.