A NEW APPROACH TO MODELING THE SUBSTRATE CURRENT OF PRESTRESSED AND POST-STRESSED MOSFETS

In this paper, we propose a closed form expression of a new and accura te analytical substrate current model for both pre-stressed and post-s tressed MOSFET's, It was derived based on the concept of effective ele ctric field, which gives a more reasonable impact ionization rate in t he lucky-electron model, This effective electric field, composed by tw o experimentally determined parameters, ran be regarded as a result of nonlocal heating effects within de,ices, This model shows a significa nt improvement to the conventional local field model. One salient feat ure of the present model is that it allows us to characterize the time evolution of the substrate current of stressed MOSFET's for the first time. Experimental verification for a wide variety of MOSFET's with e ffective channel lengths down to 0.3 mu m shows that the new model is very accurate and is feasible for any kind of MOS device with differen t drain structures, The present model can be applied to explore the ho t carrier effect in designing submicrometer MOS devices with emphasis on the design optimization of a device drain engineering issue, In add ition, the present model is well suited for device reliability analysi s and circuit level simulations.