1. L28 April 281 EE5342 – Semiconductor Device Modeling and Characterization Lecture 28 - Spring 2005 Professor Ronald L. Carter ronc@uta.edu http://www.uta.edu/ronc/

2. L28 April 282 MOSFET circuit parameters

3. L28 April 283 Estimating LAMBDA

4. L28 April 284 SPICE mosfet Model Instance CARM*, Ch. 4, p. 290 L = Ch. L. [m] W = Ch. W. [m] AD = Drain A [m 2 ] AS = Source A[m 2 ] NRD, NRS = D and S diff in squares M = device multiplier

5. L28 April 285 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. L28 April 286 SPICE Parameters Level 1 - 3 (Static)

7. L28 April 287 SPICE Parameters Level 1 - 3 (Static) * 0 = aluminum gate, 1 = silicon gate opposite substrate type, 2 = silicon gate same as substrate.

8. L28 April 288 SPICE Parameters Level 1 - 3 (Q & N)

9. L28 April 289 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. L28 April 2810 Level 1 Static Const. For Device Equations  = 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) I SD = as given, or = JS*AD I SS = as given, or = JS*AS

11. L28 April 2811 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. L28 April 2812 e - e - e - e - e - + + + + + + + + + + + + n-channel enhancement MOSFET in ohmic region 0< V T < V G V B < 0 E Ox,x > 0 Acceptors Depl Reg V S = 0 0< V D < V DS,sat n+ p-substrate Channel e- channel ele + implant ion

13. L28 April 2813 Subthreshold conduction Below O.S.I., when the total band-bending < 2|  p |, the weakly inverted channel conducts by diffusion like a BJT. Since V GS >V DS, and below OSI, then N a >n S >n D, and electr diffuse S --> D Electron concentration at Source Concentration gradient driving diffusion

14. L28 April 2814 Subthreshold current data Figure 11.4* Figure 10.1**

15. L28 April 2815 Mobility variation due to E depl Figures 11.7,8,9*

16. L28 April 2816 Velocity saturation effects Figure 11.10*

17. L28 April 2817 SPICE Parameters Level 2

18. L28 April 2818 SPICE Parameters Level 2 & 3

19. L28 April 2819 Level 2 Static Device Equations Accounts for variation of channel potential for 0 < y < L For vds < vds,sat = vgs - Vfb - PHI +  2 *[1-sqrt(1+2(vgs-Vfb-vbs)/  2 ] id,ohmic = [  /(1-LAMBDA*vds)] *[vgs - Vfb - PHI - vds/2]*vds -2  [vds+PHI-vbs) 1.5 -(PHI-vbs) 1.5 ]/3

20. L28 April 2820 Level 2 Static Device Eqs. (cont.) For vds > vds,sat id = id,sat/(1-LAMBDA*vds) where id,sat = id,ohmic(vds,sat)

21. L28 April 2821 Level 2 Static Device Eqs. (cont.) Mobility variation KP’ = KP*[(esi/eox)*UCRIT*TOX /(vgs-VTH-UTRA*vds)] UEXP This replaces KP in all other formulae.

22. L28 April 2822 SPICE Parameters Level 3

23. L28 April 2823 Project 2 Parameter Values Extracted 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"

24. L28 April 2824 Project 2 Optimized Parameter Values 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"

25. L28 April 2825 Project 2 Parameter Values Used for Data 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"

26. L28 April 2826 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