ACCURATE BASE AND COLLECTOR CURRENT MODELING OF POLYSILICON EMITTER BIPOLAR-TRANSISTORS - QUANTIFICATION OF HOLE SURFACE RECOMBINATION VELOCITY

We present predictive and accurate modeling of base and collector curr ents in poly-Si emitter bipolar transistors Ref. 1. Using a standard 0 .8 mu m bipolar complementary metal-oxide-semiconductor technology pro cess flow Ref. 2, numerous experiments are performed. The base and emi tter doping profiles are varied intentionally over a wide range in a c ontrolled manner, so as to extract a self-consistent set of apparent b and-gap narrowing, minority-carrier mobility, intrinsic concentration parameter, and Auger recombination rate that is valid for simultaneous ly modeling bipolar transistor base and collector currents. The standa rd nature of the fabrication process technology chosen for this study allows the results to be more generally applicable. The doping concent rations for physical device simulations are taken directly from second ary-ion-mass spectrometry measurements. These profiles are then verifi ed using spreading resistance measurements and capacitance-voltage mea surements. It is shown that the measured base and collector currents f or all experiments at room temperature can be fit simultaneously using Klaasen's unified apparent band-gap narrowing and mobility model Ref 3. The emitter poly-Si/epi-Si interface (surface) hole recombination v elocity is derived as a function of the emitter implant dose (arsenic concentration in the emitter) consistent with the model mentioned abov e. Sensitivity of the simulation results to model parameters is shown. It is further shown that the emitter implant dose can be used as a bi polar transistor optimization parameter. (C) 1996 American Institute o f Physics.