Title :
Modeling study of ultrathin gate oxides using direct tunneling current and capacitance-voltage measurements in MOS devices
Author :
Yang, Nian ; Henson, W. Kirklen ; Hauser, John R. ; Wortman, Jimmie J.
Author_Institution :
Dept. of Electr. & Comput. Eng., North Carolina State Univ., Raleigh, NC, USA
fDate :
7/1/1999 12:00:00 AM
Abstract :
Using both quantum mechanical calculations for the silicon substrate and a modified WKB approximation for the transmission probability, direct tunneling currents across ultra-thin gate oxides of MOS structures have been modeled for electrons from the inversion layers in p-type Si substrates. The modeled direct tunneling currents have been compared to experimental data obtained from nMOSFET´s with direct tunnel gate oxides. Excellent agreement between the model and experimental data for gate oxides as thin as 1.5 nm has been achieved. Advanced capacitance-voltage techniques have been employed to complement direct tunneling current modeling and measurements. With capacitance-voltage (C-V) techniques, direct tunneling currents can be used as a sensitive characterization technique for direct tunnel gate oxides. The effects of both silicon substrate doping concentration and polysilicon doping concentration on the direct tunneling current have also been studied as a function of applied gate voltage
Keywords :
MOSFET; capacitance; dielectric thin films; doping profiles; inversion layers; leakage currents; tunnelling; 1.5 nm; MOS devices; Si; applied gate voltage; capacitance-voltage measurements; capacitance-voltage techniques; direct tunneling current; inversion layers; modified WKB approximation; nMOSFET; polysilicon doping concentration; quantum mechanical calculations; substrate doping concentration; transmission probability; ultrathin gate oxides; Capacitance measurement; Capacitance-voltage characteristics; Doping; Electrons; MOSFET circuits; Probability; Quantum mechanics; Semiconductor process modeling; Silicon; Tunneling;
Journal_Title :
Electron Devices, IEEE Transactions on