Extraction of SPICE Model Parameters from ATLAS Device Simulation Using UTMOST

Many users would like to extract SPICE models from their process and device simulation using ATHENA and ATLAS to be used in actual circuit simulation without actually fabricating the device.

Using SILVACO's UTMOST you can extract SPICE model parameters from the simulation results of ATHENA and ATLAS.

To guide users on how to go about extracting SPICE model parameters an example which extracts BSIM3v3 model from process/device simulation is used in this article.

Figure 1. TonyPlot of Decice structure.

Figure 2. DeckBuild screen.

 

All these commands can be executed from a single software – DeckBuild.

The commands are heavily commented so that you know their functions and purpose.

Here we will concentrate on the UTMOST batch mode commands. Here we only cover a very simple case and there is no local optimization. The UTMOST interactive mode can be used save the UTMOST setup into a file . UTMOST interactive cannot be executed from DeckBuild.

----------- start of deckbuild commands -------------

# Commands that can be used in deckbuild to extract
# Spice model Parameters. The deck for TCAD is
# not complete . Below are examples of commands that
# maybe used in VWF Athena and Atlas to obtain the
# device characteristics

###### START ATHENA SIMULATION ###

# Run process simulation

go athena

# Extract the poly length LD

extract name=”ld” thick poly y.val=0
extract name=”utmost_ld”($ld*1.0e-4)
....
extract thickness oxide mat.occno=1 name=”tox”
extract name=”utmost_tox” ($tox*1.0e-10)
....

###### START ATLAS DEVICE SIMULATION ##

go atlas

###### Create the IdVg-Vb IV matrix ###

load infile=solve1.log
log outf=mos2ex06_IdVg-Vb.log
solve name=gate vgate=0 vfinal=5 vstep=0.2
load infile=solve2.log
solve name=gate vgate=0 vfinal=5 vstep=0.2
load infile=solve3.log
solve name=gate vgate=0 vfinal=5 vstep=0.2
....

# Simulate device ID/VG characteristics

solve vgate=1 vstep=0.25 vfinal=1.5 name=gate \ outf=solve_tmp0 onefile
solve vgate=1.75 vstep=0.25 vfinal=3 name=gate \ outf=solve_tmp1 onefile
solve vgate=3.25 vstep=0.25 vfinal=4.5 name=gate \ outf=solve_tmp2 onefile
....

##### Create the IdVd-Vg IV matrix #######

log outf=mos2ex06_IdVd-Vg.log
....
solve name=drain vdrain=0 vfinal=5 vstep=0.2
solve name=drain vdrain=0 vfinal=5 vstep=0.2
solve name=drain vdrain=0 vfinal=5 vstep=0.2
....

#### START UTMOST SIMULATION ####

#*************************************
# Jump to UTMOST MOS module

go utmost
utmost type = mos

# The model command loads Utmost setup file
# created by interactive session .

model MOS_vwf_bsim3_n

# change the Value for gate oxide thickness for
#Opt(imization) and Fit Columns .

device TOX = $utmost_tox

# define parameters to be set when the data is
# read from ssf file from ATLAS

setup NRS=0.04 NRD=0.04 width=1.0 length=$utmost_ld polarity=N

# load Atlas log files simulated earlier.
# the master option tells UTMOST the file is in
# VWF ssf format

init inf=mos2ex06_IdVg-Vb.log master

# Load in append mode, more results from the logfile

init inf=mos2ex06_IdVd-Vg.log master append

# select required characteristics for device 1
# unselect all ID/VG-VB first the select device 1
# (there is only 1 device)

deselect ID/VG-VB all
select ID/VG-VB device 1

# unselect all ID/VD-VG first, then select device 1

deselect ID/VD-VG all
select ID/VD-VG device 1

# Defines the routine for which data is to be stored
# in ssf format (standard structure format)

output ID/VD-VG

# Stores measured data (simulated by ATLAS) to
# ssf log File in uniform steps as required by UTMOST

log outf=mos2ex06_data.log measured

# setup the UTMOST log file to store
# The measured (simulated data from ATLAS).

log outf=mos2ex06_ut.log utmost

# set up output log file for simulated data created
#by UTMOST routine which was last referred to
#by batch mode output command i.e ID/VD-VG

log outf=mos2ex06_sim.log simulated

# Perform curve fitting for selected routines
# and then do local optimization sequences
# if they are defined in setup file.

fit ID/VG-VB
fit ID/VD-VG

# perform simulation for selected routines

simulate ID/VD-VG

# Output Utmost parameters for extraction.
# Save results to file in a ssf file. If
# append option is used the parameters are appended
# to an existing file.

save outf=mos2ex06.ssf

##### Extract UTMOST parameters ########

# load output parameter file from UTMOST

extract init infile=”mos2ex06.ssf”

# Save the current parameter set from the
# Optimization column of UTMOST parameter
# to a model library file

create library=mos2ex06.lib

# EXIT

quit

------------ end of Deckbuild commands -----------

 

A portion of mos2ex06.lib file is as follows.

.LIB CMOS
*
.MODEL MMOD NMOS ( LEVEL = 8

+TNOM = 27 TOX = 1E-8 XJ = 1.5E-7
+NCH=1.7E17
NSUB=6E16 VTH0 =0.5776647
+K1= 0.5
K2 = -0.0186
K3 = 80
+K3B= 0
W0= 2.5E-6
NLX = 1.74E-7
+DVT0W= 0
DVT1W= 0
DVT2W =-0.032
+DVT0 = 2.2
DVT1 = 0.53
DVT2 = -0.032
+VBM= -5
U0 = 670
UA= 2.25E-9
+UB= 5.87E-19
UC= -4.65E-11
VSAT= 8E4
+A0 = 1
AGS = 0
B0= 0
+B1 = 0
KETA = -0.047
A1 = 0
+A2 = 1
RDSW = 0
PRWG = 0
+PRWB = 0
WR = 1
PRWG = 0
+LINT = 0
DWG = 0
DWB = 0
+VOFF = -0.1
NFACTOR = 1
CIT = 0
+CDSC = 2.4E-4
CDSCD = 0
CDSCB = 0
+ETA0 = 0.08
ETAB = -0.07
DSUB = 0.56
+PCLM = 1.3
PDIBLC1 = 0.39
PDIBLC2 = 8.6E-3
+PDIBLCB= 0
DROUT = 0.56
PSCBE1 = 4.24E8
+PSCBE2 = 5E-5
PVAG = 0
DELTA = 0.01
+MOBMOD = 1
PRT = 0
UTE = -1.5
+KT1 = 0
KT1L = 0
KT2 = 0
+UA1 = 4.31E-9
UB1 = -7.61E-18
UC1 = -5.6E-11
+AT = 3.3E4
NQSMOD = 0
WL = 0
+WLN = 1
WW = 0
WWN = 1
+WWL = 0
LL = 0
LLN = 1
+LW = 0
LWN = 1
LWL = 0
+CAPMOD = 1
)
 
*
   

 

References

  1. UTMOST III User’s Manual – Chap 14. Batch Mode Operation
  2. UTMOST III Extractions Manual , Vol. 1- Appendix A – BSIM3v3 Extraction Tutorial
    3] Silvaco example file examples/mos2/mos2ex6.in
    4] TCAD Tutorial and Examples Vol.1 p.2-26


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