The influence of ion energy of phosphorus implanted in source and drain regions on the electron gas heating in n-channels silicon submicron MOSFETs

The influence of the energy of phosphorous ions which are implanted in source and drain regions of n-channel silicon submicron MOSFET on the electron heating is studied. It is taken into account that the lateral scattering of ions causes their penetration to the subgate region. The depth of such penetration can be quite sufficient to change the electric field in transistor significantly. Thus, the penetration has influence on the electron transport. The electron drift is studied by means of Monte Carlo simulation. The electric field is calculated using the original procedure of Poisson equation solving that takes into account smoothness of drain and source regions boundaries as well as the space distribution of electrons in the simulating area. This model allows to estimate the influence of the depth of ion penetration to the subgate region on the device electric characteristics. Using the developed model, the process of electron heating in the MOSFETs with channel lengths 200 nm and 300 nm source and drain regions are formed by ion implantation with energies 20, 40, 70 and 90 keV. Therefore, it is shown that the lateral ion scattering at implantation has significant influence on the electron gas heating in the channel. That is why for the correct simulation of hot electron transport in MOSFET it is necessary to calculate exactly the impurity profiles of the source and drain regions boundaries. (authors)