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EE5342 – Semiconductor Device Modeling and Characterization Lecture 30 - Spring 2004

EE5342 – Semiconductor Device Modeling and Characterization Lecture 30 - Spring 2004. Professor Ronald L. Carter ronc@uta.edu http://www.uta.edu/ronc/. MOSFET circuit parameters. Estimating LAMBDA. L = Ch. L. [m] W = Ch. W. [m] AD = Drain A [m 2 ] AS = Source A[m 2 ] NRD, NRS = D and

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EE5342 – Semiconductor Device Modeling and Characterization Lecture 30 - Spring 2004

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  1. EE5342 – Semiconductor Device Modeling and CharacterizationLecture 30 - Spring 2004 Professor Ronald L. Carter ronc@uta.edu http://www.uta.edu/ronc/

  2. MOSFET circuitparameters

  3. Estimating LAMBDA

  4. L = Ch. L. [m] W = Ch. W. [m] AD = Drain A [m2] AS = Source A[m2] NRD, NRS = D and S diff in squares M = device multiplier SPICE mosfet Model Instance CARM*, Ch. 4, p. 290

  5. SPICE mosfet model levels • Level 1 is the Schichman-Hodges model • Level 2 is a geometry-based, analytical model • Level 3 is a semi-empirical, short-channel model • Level 4 is the BSIM1 model • Level 5 is the BSIM2 model, etc.

  6. SPICE ParametersLevel 1 - 3 (Static)

  7. SPICE ParametersLevel 1 - 3 (Static) * 0 = aluminum gate, 1 = silicon gate opposite substrate type, 2 = silicon gate same as substrate.

  8. SPICE ParametersLevel 1 - 3 (Q & N)

  9. Level 1 Static Const.For Device Equations Vfb = -TPG*EG/2 -Vt*ln(NSUB/ni) - q*NSS*TOX/eOx VTO = as given, or = Vfb + PHI + GAMMA*sqrt(PHI) KP = as given, or = UO*eOx/TOX CAPS are spice pars., technological constants are lower case

  10. Level 1 Static Const.For Device Equations b = KP*[W/(L-2*LD)] = 2*K, K not spice GAMMA = as given, or = TOX*sqrt(2*eSi*q*NSUB)/eOx 2*phiP = PHI = as given, or = 2*Vt*ln(NSUB/ni) ISD = as given, or = JS*AD ISS = as given, or = JS*AS

  11. Level 1 Static Device Equations vgs < VTH, ids = 0 VTH < vds + VTH < vgs, id = KP*[W/(L-2*LD)]*[vgs-VTH-vds/2] *vds*(1 + LAMBDA*vds) VTH < vgs < vds + VTH, id = KP/2*[W/(L-2*LD)]*(vgs - VTH)^2 *(1 + LAMBDA*vds)

  12. n-channel enhancementMOSFET in ohmic region 0< VT< VG e- channel ele + implant ion Channel VS = 0 0< VD< VDS,sat EOx,x> 0 n+ n+ e-e- e- e- e- ++++++++++++ Depl Reg p-substrate Acceptors VB < 0

  13. Subthreshold conduction • Below O.S.I., when the total band-bending < 2|fp|, the weakly inverted channel conducts by diffusion like a BJT. • Since VGS>VDS, and below OSI, then Na>nS >nD, and electr diffuse S --> D Electron concentration at Source Concentration gradient driving diffusion

  14. Subthreshold current data Figure 10.1** Figure 11.4*

  15. Mobility variationdue to Edepl Figures 11.7,8,9*

  16. Velocity saturationeffects Figure 11.10*

  17. SPICE ParametersLevel 2

  18. SPICE ParametersLevel 2 & 3

  19. Level 2 StaticDevice Equations Accounts for variation of channel potential for 0 < y < L For vds < vds,sat = vgs - Vfb - PHI + g2*[1-sqrt(1+2(vgs-Vfb-vbs)/g2] id,ohmic = [b/(1-LAMBDA*vds)] *[vgs - Vfb - PHI - vds/2]*vds -2g[vds+PHI-vbs)1.5-(PHI-vbs)1.5]/3

  20. Level 2 StaticDevice Eqs. (cont.) For vds > vds,sat id = id,sat/(1-LAMBDA*vds) where id,sat = id,ohmic(vds,sat)

  21. Level 2 StaticDevice Eqs. (cont.) Mobility variation KP’ = KP*[(esi/eox)*UCRIT*TOX /(vgs-VTH-UTRA*vds)]UEXP This replaces KP in all other formulae.

  22. SPICE ParametersLevel 3

  23. Project 3 • Project 3 is posted on the web • See www.uta.edu/ronc/ 5342/projects/5342Project3.pdf

  24. IS " 891.8a" BF " 113.6 " NF " 1.044 " VAF " 83.50 " IKF " 13.45m" ISE " 20.40f" NE " 1.772 " BR " 2.270 " NR " 1.013 " VAR " 22.92 " IKR " 2.000m" ISC " 537.6f" NC " 1.675 " RB " 1.233K" IRB " 1.000u" RBM " 151.8 " RE " 2.560 " RC " 26.00 " CJE " 2.344p" VJE " 762.0m" MJE " 344.9m" CJC " 1.234p" VJC " 570.8m" MJC " 347.6m" CJS " 100.4f" VJS " 566.0m" MJS " 267.0m" Project 2 Parameter Values Extracted

  25. IS " 890.9a" BF " 123.7 " NF " 1.043 " VAF " 86.04 " IKF " 14.33m" ISE " 28.54f" NE " 1.878 " BR " 2.657 " NR " 1.012 " VAR " 21.25 " IKR " 6.470m" ISC " 537.6f" NC " 1.675 " RB " 1.233K" IRB " 986.9n" RBM " 122.2 " RE " 2.831 " RC " 11.71 " CJE " 2.344p" VJE " 762.0m" MJE " 344.9m" CJC " 1.234p" VJC " 570.8m" MJC " 347.6m" CJS " 100.4f" VJS " 566.0m" MJS " 267.0m" Project 2 Optimized Parameter Values

  26. IS " 891.0a" BF " 123.0 " NF " 1.043 " VAF " 86.95 " IKF " 14.91m" ISE " 28.86f" NE " 1.876 " BR " 2.345 " NR " 1.012 " VAR " 23.45 " IKR " 23.45m" ISC " 1.095p" NC " 1.875 " RB " 1.234K" IRB " 987.0n" RBM " 123.0 " RE " 2.345 " RC " 5.678 " CJE " 2.345p" VJE " 765.4m" MJE " 345.6m" CJC " 1.234p" VJC " 567.8m" MJC " 345.6m" CJS " 100.4f" VJS " 566.8m" MJS " 269.6m" Project 2 Parameter Values Used for Data

  27. References • CARM = Circuit Analysis Reference Manual, MicroSim Corporation, Irvine, CA, 1995. • M&A = Semiconductor Device Modeling with SPICE, 2nd ed., by Paolo Antognetti and Giuseppe Massobrio, McGraw-Hill, New York, 1993. • M&K = Device Electronics for Integrated Circuits, 2nd ed., by Richard S. Muller and Theodore I. Kamins, John Wiley and Sons, New York, 1986. • Semiconductor Physics and Devices, by Donald A. Neamen, Irwin, Chicago, 1997

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