Hot-Carrier Effects in Single- and Double-Gate Thin-Film SOI MOSFETs

Hot carrier effects are investigated in single-and double-gate thin film SOI MOSFETs. The comparison of hot-carrier-induced degradation in partially and fully devices shows the substantial influence of the depletion of the thin Si film. These behaviors are attributed to the different degrees of confinement of the electrons close to the Si/SiO2 interface associated with the magnitude of the transverse electric field. A detailed study is also carried out in order to show the influence of a double-gate operation. In this case, a substantial reduction of the degradation of the main electrical properties is obtained compared with that of a single-gate operation. This dramatic improvement in the double-gate case is due to the strong inversion of the whole silicon film. The volume inversion leads to a decrease of the gate oxide degradation associated with the reduction of the lateral electric field, and induces a reduction of the coulomb scattering for carriers which are located in the centre of the Si film, far from the interfaces, which constitutes a significant part of the electrical conduction in these double-gate SOI MOSFETs.