Non-equilibrium modeling of tunneling gate currents in nanoscale MOSFETs

Abstract We calculate gate currents of ultrashort MOSFETs with ultrathin gate oxides for different gate and drain biases by directly solving the Schrodinger, electron-Boltzmann, Poisson and hole-continuity equations. Computations give rise to a subband structure that is populated using the calculated distribution function. The calculated tunneling current versus gate voltage curves show oscillatory structure which reflects quantum effects. For very low drain bias voltages, current is found to be generated from low energy electrons especially from tunneling through the gate/LDD overlap regions. For drain biases at pinch-off, tunneling is significant from low energy electrons near the source, as well as from higher energy electrons near the drain.

[1]  Neil Goldsman,et al.  2-D MOSFET modeling including surface effects and impact ionization by self-consistent solution of the Boltzmann, Poisson, and hole-continuity equations , 1997 .

[2]  Huang Chung-Kuang,et al.  Self-Consistent Solution of Schrödinger Equation, Boltzmann Transport Equation, Poisson and Current-continuity Equation for MOSFET , 2001 .

[3]  N. Goldsman,et al.  Electron energy distribution for calculation of gate leakage current in MOSFETs , 1988 .

[4]  Andreas Schenk,et al.  Modeling and simulation of tunneling through ultra-thin gate dielectrics , 1997 .

[5]  E. Merzbacher.  Quantum mechanics , 1961 .

[6]  A. Tasch,et al.  A pseudo-lucky electron model for simulation of electron gate current in submicron NMOSFET's , 1996 .

[7]  Jimmy Xu,et al.  A quantum gate current model , 1993 .

[8]  Walter A. Harrison,et al.  Tunneling from an Independent-Particle Point of View , 1961 .

[9]  Analysis of quantum effects in nonuniformly doped MOS structures , 1998 .

[10]  Yuan Taur,et al.  CMOS devices below 0.1 /spl mu/m: how high will performance go? , 1997, International Electron Devices Meeting. IEDM Technical Digest.

[11]  S. Laux,et al.  Understanding hot‐electron transport in silicon devices: Is there a shortcut? , 1995 .

[12]  Tierney,et al.  Ballistic electron transport in thin silicon dioxide films. , 1987, Physical review. B, Condensed matter.

[13]  Z. Weinberg,et al.  On tunneling in metal‐oxide‐silicon structures , 1982 .

[14]  Tak H. Ning,et al.  Emission probability of hot electrons from silicon into silicon dioxide , 1977 .

[15]  T. Morimoto,et al.  Study of the manufacturing feasibility of 1.5-nm direct-tunneling gate oxide MOSFETs: uniformity, reliability, and dopant penetration of the gate oxide , 1998 .

[16]  T. Ma,et al.  Tunneling leakage current in ultrathin (<4 nm) nitride/oxide stack dielectrics , 1998, IEEE Electron Device Letters.

[17]  A. Tasch,et al.  Modeling gate leakage current in nMOS structures due to tunneling through an ultra-thin oxide , 1998 .

[18]  A. Ghetti,et al.  Progress toward 10 nm CMOS devices , 1998, International Electron Devices Meeting 1998. Technical Digest (Cat. No.98CH36217).

[19]  J. Shewchun,et al.  Theoretical tunneling current characteristics of the SIS (semiconductor‐insulator‐semiconductor) diode , 1972 .

[20]  Y. Taur,et al.  Quantum-mechanical modeling of electron tunneling current from the inversion layer of ultra-thin-oxide nMOSFET's , 1997, IEEE Electron Device Letters.

[21]  J. Wortman,et al.  Modeling study of ultrathin gate oxides using direct tunneling current and capacitance-voltage measurements in MOS devices , 1999 .

[22]  S. Datta.  Electronic transport in mesoscopic systems , 1995 .

[23]  P. Dollfus,et al.  STUDY OF DIRECT TUNNELING THROUGH ULTRATHIN GATE OXIDE OF FIELD EFFECT TRANSISTORS USING MONTE CARLO SIMULATION , 1999 .

[24]  William R. Frensley,et al.  An efficient method for the numerical evaluation of resonant states , 1994 .

[25]  A. Benvenuti,et al.  Self-consistent 2-D model for quantum effects in n-MOS transistors , 1998 .

[26]  William H. Press,et al.  Numerical recipes in C , 2002 .

[27]  D. Lippens,et al.  Capacitance engineering for InP-based heterostructure barrier varactor , 1998, IEEE Electron Device Letters.

[28]  Zhiping Yu,et al.  Effective density-of-states approach to QM correction in MOS structures , 2000 .

[29]  A. Hartstein,et al.  Effect of silicon orientation and hydrogen anneal on tunneling from Si into SiO2 , 1983 .

[30]  Craig S. Lent,et al.  The quantum transmitting boundary method , 1990 .

[31]  S. Selberherr.  Analysis and simulation of semiconductor devices , 1984 .

[32]  S. Mudanai,et al.  Modeling of direct tunneling current through gate dielectric stacks , 2000 .

[33]  John D. Bruno,et al.  Resonant level lifetime in GaAs/AlGaAs double‐barrier structures , 1987 .

[34]  S. Datta.  Nanoscale device modeling: the Green’s function method , 2000 .

[35]  Gerald Lucovsky,et al.  Tunneling currents through ultrathin oxide/nitride dual layer gate dielectrics for advanced microelectronic devices , 1998 .

[36]  Neil Goldsman,et al.  Gate leakage current simulation by Boltzmann transport equation and its dependence on the gate oxide thickness , 1999, 1999 International Conference on Simulation of Semiconductor Processes and Devices. SISPAD'99 (IEEE Cat. No.99TH8387).