L27 April 241 Semiconductor Device Modeling & Characterization Lecture 27 Professor Ronald L. Carter Spring 2001

L27 April 242 MOSFET Device Structre Fig. 4-1, M&A*

L27 April 243 n-channel enh. circuit model G D B S C gs C gd C gb C bs C bd RD RG RB RDS Idrain D SS D SD

L27 April 244 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

L27 April 245 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.

L27 April 246 SPICE Parameters Level (Static)

L27 April 247 SPICE Parameters Level (Static) * 0 = aluminum gate, 1 = silicon gate opposite substrate type, 2 = silicon gate same as substrate.

L27 April 248 SPICE Parameters Level (Q & N)

L27 April 249 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

L27 April 2410 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

L27 April 2411 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*[W/(L-2*LD)]*(vgs - VTH)^2 *(1 + LAMBDA*vds)

L27 April 2412 SPICE Parameters Level 2

L27 April 2413 SPICE Parameters Level 2 & 3

L27 April 2414 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

L27 April 2415 Level 2 Static Device Eqs. (cont.) For vds > vds,sat id = id,sat/(1-LAMBDA*vds) where id,sat = id,ohmic(vds,sat)

L27 April 2416 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.

L27 April 2417 SPICE Parameters Level 3

L27 April 2418 References CARM = Circuit Analysis Reference Manual, MicroSim Corporation, Irvine, CA, M&A = Semiconductor Device Modeling with SPICE, 2nd ed., by Paolo Antognetti and Giuseppe Massobrio, McGraw-Hill, New York, 1993.