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 currents in poly-Si emitter bipolar transistors Ref. 1. Using a standard 0.8 mu m bipolar complementary metal-oxide-semiconductor technology process flow Ref. 2, numerous experiments are performed. The base and emitter doping profiles are varied intentionally over a wide range in a controlled manner, so as to extract a self-consistent set of apparent band-gap narrowing, minority-carrier mobility, intrinsic concentration parameter, and Auger recombination rate that is valid for simultaneously modeling bipolar transistor base and collector currents. The standard nature of the fabrication process technology chosen for this study allows the results to be more generally applicable. The doping concentrations for physical device simulations are taken directly from secondary-ion-mass spectrometry measurements. These profiles are then verified using spreading resistance measurements and capacitance-voltage measurements. It is shown that the measured base and collector currents for 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 velocity is derived as a function of the emitter implant dose (arsenic concentration in the emitter) consistent with the model mentioned above. Sensitivity of the simulation results to model parameters is shown. It is further shown that the emitter implant dose can be used as a bipolar transistor optimization parameter. (C) 1996 American Institute of Physics.