Lateral profiling of impurity surface concentration in submicron metal–oxide–silicon transistors

Theory and line-shape analysis of carrier recombination current at interfacial electronic traps under a surface controlling gate in metal–oxide–silicon (MOS) structures is investigated using the Shockley–Read–Hall recombination statistics. The theoretical analysis demonstrates the sensitive dependence of the line shape of the peaked basewell-terminal recombination current versus gate/base voltage (IB–VGB) characteristics on the lateral variation of the impurity concentration along the surface channel. An electrical measurement method is presented based on this discovery for extracting the impurity surface concentration profile NIM(x=0, y, z) in the five regions (basewell, drain and source junction and extension) covered by the gate conductor in submicron MOS transistors. Impurity surface concentration profiles in the basewell channel region are then extracted by the analytical theory for MOS transistors fabricated by an advanced 0.13 μm complementary MOS technology. Effects of nitrogen in the gate oxide and current generated in the drain and source extension regions for profiling the NIM in the extension regions are illustrated.