DETAILED CHARACTERIZATION AND ANALYSIS OF THE BREAKDOWN VOLTAGE IN FULLY DEPLETED SOI N-MOSFETS

The breakdown voltage in fully depleted SOI n-MOSFET's has been studie d over a wide range of film thicknesses, channel dopings, and channel lengths. In lightly-doped films, the breakdown voltage roll-off at sho rter channel lengths becomes much less severe as the film thickness is reduced. This is a result of improved resistance to punchthrough and DIBL effects in thinner SOI. Consequently, at channel lengths below ab out 0.8 mum, ultrathin (50 nm) SOI can provide better breakdown voltag es than thicker films. At heavier doping levels the punchthrough and D IBL are suppressed, and there is little dependence of breakdown voltag e on film thickness. Two-dimensional simulations have been used to inv estigate the breakdown behavior in these devices. It is found that the drain-induced barrier lowering affects the breakdown voltage both dir ectly, via punchthrough, and indirectly through its effect on the curr ent flow and hole generation in the high-field regions.