I am trying to run some 7 nm simulations with NGSPICE, and I would like to know if my results are believable or not. I am using the ASAP7 transistor model, which I have converted from HSPICE to NGSPICE. I am not interested in completely precise results - as NGSPICE cannot do noise anyways, but it would be good to know if the results are in the ballpark of the HSPICE results or not.
I used the following file (TT - typical/typical, slvt - because that is the standard VT):
I used NGSPICE-41, which seems to already include the compiled OSDI modules, so I did not need to download and use the OpenVAF compiler to get BSIMCMG_va.osdi unlike what the documentation says.
https://gigenet.dl.sourceforge.net/project/ngspice/ng-spice-rework/41/ngspice-41_64.7z
Also in spinit the below line was already commented out:
* unset osdi_enabled
When converting the slvt pmos and nmos models from that file, what needed is to specify TYPE=0/1 in NGSPICE, otherwise it does not work.
This is all what is needed to added BTW:
.model BSIMCMG_osdi_P BSIMCMG_va (
+ TYPE = 0
After conversion, running the simulation results in the following warnings:
.model bsimcmg_osdi_n bsimcmg_va ( type=1 version=107 bulkmod=1 igcmod=1 ...
unrecognized parameter (version) - ignored
unrecognized parameter (coremod) - ignored
unrecognized parameter (capmod) - ignored
unrecognized parameter (nseg) - ignored
unrecognized parameter (etaqm) - ignored
I compared the values from 7nm_TT_160803.pm to the following file from ngspice-41_64.7z: ngspice-41_64\Spice64\examples\osdi\bsimcmg\Modelcards\modelcard.pmos
- version is completely understandable, as the models were made by different companies.
- coremod/capmod is understandable, they are missing from modelcard.pmos, and they are set to 0 anyways.
- nseg/etaqm can be found in both files with the same values, so why it has not been deleted from modelcard.pmos is a mistery, but whatever.
However, there are a lot of small and some big differences which I do not understand, and they might make the simulations completely different relative to HSPICE:
- small differences which might be because the node differences (ASAP7 right):
at=0.0008234 / at=0.001
cgdo=1e-10 / cgdo=1.6e-10
cgso=1e-10 / cgso=1.6e-10
dsub=0.5 / dsub=0.24
dvt0=0.05006 / dvt0=0.05
dvt1=0.4 / dvt1=0.36
eot=2.1e-9 / eot=1e-9
eta0=0.03952 / eta0=0.094
hfin=3e-8 / hfin=3.2e-8
igt=3.5 / igt=2.5
phig=4.678 / phig=4.9278
ptwg=6.322 / ptwg=25
ptwgt=0.0015 / ptwgt=0.004
rdsw=190.6 / rdsw=200
tgidl=-0.01 / tgidl=-0.007
u0=0.02935 / u0=0.0237
ua1=0.00134 / ua1=0.001032
vsat=48390 / vsat=60000
- small differences where ASAP7 uses 0, I guess they decided not to simulate these.
cfd=0.2e-10 / cfd=0
cfs=0.2e-10 / cfs=0
deltawcv=-1e-8 / deltawcv=0
dlc=-9.2e-9 / dlc=0
kt1=0.08387 / kt1=0
prt=0.002477 / prt=0
utl=0.001 / utl=0
- small differences where NGSPICE uses 0, maybe the OSDI module does not support them.
ucste=0 / ucste=-0.004775
ute=0 / ute=-1.2
xl=0 / xl=1e-9
So far so good, while I have no idea what these parameters above are, the differences do not seem that huge. But then what about the ones below?
- The difference is huge. Is it a problem?
deltavsat=11.56 / deltavsat=0.17
geomod=0 / geomod=1
- Only the OSDI in ASAP7 seems to need them, is it a problem?
- / fpitch=2.7e-8
- / l=2.1e-8
- / tfin=6.5e-9
- / toxg=1.8e-9
- Only the OSDI in NGSPICE seems to need them, is it a problem?
pclmcv=0.013 / -
Since I have know nothing about these parameters, any information would be good. Or if somebody would run the simulations in HSPICE would be fine as well.
"test1.sp" is a simulation of an inverter train. I ignore the first and last inverters, as the first is driven by a clock with arbitrary slew, and the last does not drive anything. At the 0.35 V half point, the delay is between 2-3 ps, which looks reasonable.
.include 'asap7_TT_slvt.sp'
.global vdd! gnd!
.SUBCKT inv in out
Npmos vdd! in out vdd! BSIMCMG_osdi_P
Nnmos gnd! in out gnd! BSIMCMG_osdi_N
.ENDS
Vvdd vdd! 0 dc=0.7
Vgnd gnd! 0 dc=0
Vin inv_in 0 pulse (0 0.7 20p 10p 10p 20p 500p)
Xinv1 inv_in inv_x1 inv
Xinv2 inv_x1 inv_out inv
Xinv3 inv_out inv_ignore inv
.tran 0.1p 100p
.control
run
set xbrushwidth=3
plot inv_in inv_x1 inv_out
.endc
.end
"test2.sp" is the same simulations where every inverter drives for other inverters, but the output of 3 of the 4 are ignored. This creates slower transitions as expected. At the 0.35 V half point, the delay is between 6-7 ps, which looks reasonable but I am not a chip designer so who knows?
.include 'asap7_TT_slvt.sp'
.global vdd! gnd!
.SUBCKT inv in out
Npmos vdd! in out vdd! BSIMCMG_osdi_P
Nnmos gnd! in out gnd! BSIMCMG_osdi_N
Npmos2 vdd! in out2 vdd! BSIMCMG_osdi_P
Nnmos2 gnd! in out2 gnd! BSIMCMG_osdi_N
Npmos3 vdd! in out3 vdd! BSIMCMG_osdi_P
Nnmos3 gnd! in out3 gnd! BSIMCMG_osdi_N
Npmos4 vdd! in out4 vdd! BSIMCMG_osdi_P
Nnmos4 gnd! in out4 gnd! BSIMCMG_osdi_N
.ENDS
Vvdd vdd! 0 dc=0.7
Vgnd gnd! 0 dc=0
Vin inv_in 0 pulse (0 0.7 20p 10p 10p 20p 500p)
Xinv1 inv_in inv_x1 inv
Xinv2 inv_x1 inv_out inv
Xinv3 inv_out inv_ignore inv
.tran 0.1p 100p
.control
run
set xbrushwidth=3
plot inv_in inv_x1 inv_out
.endc
.end
They both include the common file asap7_TT_slvt.sp:
**** copied from asap7\asap7PDK_r1p7\models\hspice\7nm_TT_160803.pm
** Hspice modelcard
.model BSIMCMG_osdi_P BSIMCMG_va (
+ TYPE = 0
* .model pmos_slvt pmos level = 72
************************************************************
* general *
************************************************************
+version = 107 bulkmod = 1 igcmod = 1 igbmod = 0
+gidlmod = 1 iimod = 0 geomod = 1 rdsmod = 0
+rgatemod= 0 rgeomod = 0 shmod = 0 nqsmod = 0
+coremod = 0 cgeomod = 0 capmod = 0 tnom = 25
+eot = 1e-009 eotbox = 1.4e-007 eotacc = 3e-010 tfin = 6.5e-009
+toxp = 2.1e-009 nbody = 1e+022 phig = 4.9278 epsrox = 3.9
+epsrsub = 11.9 easub = 4.05 ni0sub = 1.1e+016 bg0sub = 1.17
+nc0sub = 2.86e+025 nsd = 2e+026 ngate = 0 nseg = 5
+l = 2.1e-008 xl = 1e-009 lint = -2.5e-009 dlc = 0
+dlbin = 0 hfin = 3.2e-008 deltaw = 0 deltawcv= 0
+sdterm = 0 epsrsp = 3.9
+toxg = 1.8e-009
************************************************************
* dc *
************************************************************
+cit = 0 cdsc = 0.003469 cdscd = 0.001486 dvt0 = 0.05
+dvt1 = 0.36 phin = 0.05 eta0 = 0.094 dsub = 0.24
+k1rsce = 0 lpe0 = 0 dvtshift= 0 qmfactor= 0
+etaqm = 0.54 qm0 = 2.183e-012 pqm = 0.66 u0 = 0.0237
+etamob = 4 up = 0 ua = 1.133 eu = 0.05
+ud = 0.0105 ucs = 0.2672 rdswmin = 0 rdsw = 200
+wr = 1 rswmin = 0 rdwmin = 0 rshs = 0
+rshd = 0 vsat = 60000 deltavsat= 0.17 ksativ = 1.592
+mexp = 2.491 ptwg = 25 pclm = 0.01 pclmg = 1
+pdibl1 = 800 pdibl2 = 0.005704 drout = 4.97 pvag = 200
+fpitch = 2.7e-008 rth0 = 0.15 cth0 = 1.243e-006 wth0 = 2.6e-007
+lcdscd = 0 lcdscdr = 0 lrdsw = 1.3 lvsat = 1441
************************************************************
* leakage *
************************************************************
+aigc = 0.007 bigc = 0.0015 cigc = 1 dlcigs = 5e-009
+dlcigd = 5e-009 aigs = 0.006 aigd = 0.006 bigs = 0.001944
+bigd = 0.001944 cigs = 1 cigd = 1 poxedge = 1.152
+agidl = 2e-012 agisl = 2e-012 bgidl = 1.5e+008 bgisl = 1.5e+008
+egidl = 1.142 egisl = 1.142
************************************************************
* rf *
************************************************************
************************************************************
* junction *
************************************************************
************************************************************
* capacitance *
************************************************************
+cfs = 0 cfd = 0 cgso = 1.6e-010 cgdo = 1.6e-010
+cgsl = 0 cgdl = 0 ckappas = 0.6 ckappad = 0.6
+cgbo = 0 cgbl = 0
************************************************************
* temperature *
************************************************************
+tbgasub = 0.000473 tbgbsub = 636 kt1 = 0 kt1l = 0
+ute = -1.2 utl = 0 ua1 = 0.001032 ud1 = 0
+ucste = -0.004775 at = 0.001 ptwgt = 0.004 tmexp = 0
+prt = 0 tgidl = -0.007 igt = 2.5
************************************************************
* noise *
************************************************************
**)
** Hspice modelcard
.model BSIMCMG_osdi_N BSIMCMG_va (
+ TYPE = 1
* .model nmos_slvt nmos level = 72
************************************************************
* general *
************************************************************
+version = 107 bulkmod = 1 igcmod = 1 igbmod = 0
+gidlmod = 1 iimod = 0 geomod = 1 rdsmod = 0
+rgatemod= 0 rgeomod = 0 shmod = 0 nqsmod = 0
+coremod = 0 cgeomod = 0 capmod = 0 tnom = 25
+eot = 1e-009 eotbox = 1.4e-007 eotacc = 1e-010 tfin = 6.5e-009
+toxp = 2.1e-009 nbody = 1e+022 phig = 4.2466 epsrox = 3.9
+epsrsub = 11.9 easub = 4.05 ni0sub = 1.1e+016 bg0sub = 1.17
+nc0sub = 2.86e+025 nsd = 2e+026 ngate = 0 nseg = 5
+l = 2.1e-008 xl = 1e-009 lint = -2e-009 dlc = 0
+dlbin = 0 hfin = 3.2e-008 deltaw = 0 deltawcv= 0
+sdterm = 0 epsrsp = 3.9
+toxg = 1.80e-009
************************************************************
* dc *
************************************************************
+cit = 0 cdsc = 0.01 cdscd = 0.01 dvt0 = 0.05
+dvt1 = 0.47 phin = 0.05 eta0 = 0.07 dsub = 0.35
+k1rsce = 0 lpe0 = 0 dvtshift= 0 qmfactor= 2.5
+etaqm = 0.54 qm0 = 0.001 pqm = 0.66 u0 = 0.0303
+etamob = 2 up = 0 ua = 0.55 eu = 1.2
+ud = 0 ucs = 1 rdswmin = 0 rdsw = 200
+wr = 1 rswmin = 0 rdwmin = 0 rshs = 0
+rshd = 0 vsat = 70000 deltavsat= 0.2 ksativ = 2
+mexp = 4 ptwg = 30 pclm = 0.05 pclmg = 0
+pdibl1 = 0 pdibl2 = 0.002 drout = 1 pvag = 0
+fpitch = 2.7e-008 rth0 = 0.225 cth0 = 1.243e-006 wth0 = 2.6e-007
+lcdscd = 5e-005 lcdscdr = 5e-005 lrdsw = 0.2 lvsat = 0
************************************************************
* leakage *
************************************************************
+aigc = 0.014 bigc = 0.005 cigc = 0.25 dlcigs = 1e-009
+dlcigd = 1e-009 aigs = 0.0115 aigd = 0.0115 bigs = 0.00332
+bigd = 0.00332 cigs = 0.35 cigd = 0.35 poxedge = 1.1
+agidl = 1e-012 agisl = 1e-012 bgidl = 10000000 bgisl = 10000000
+egidl = 0.35 egisl = 0.35
************************************************************
* rf *
************************************************************
************************************************************
* junction *
************************************************************
************************************************************
* capacitance *
************************************************************
+cfs = 0 cfd = 0 cgso = 1.6e-010 cgdo = 1.6e-010
+cgsl = 0 cgdl = 0 ckappas = 0.6 ckappad = 0.6
+cgbo = 0 cgbl = 0
************************************************************
* temperature *
************************************************************
+tbgasub = 0.000473 tbgbsub = 636 kt1 = 0 kt1l = 0
+ute = -0.7 utl = 0 ua1 = 0.001032 ud1 = 0
+ucste = -0.004775 at = 0.001 ptwgt = 0.004 tmexp = 0
+prt = 0 tgidl = -0.007 igt = 2.5
************************************************************
* noise *
************************************************************
**)
"from 7nm_TT_160803 pm.txt" and "from modelcard pmos.txt" are the parameters from the two different sources, sorted and converted to similar diffable formats. I have uploaded all the files here:
https://drive.google.com/file/d/11-vKHFhfnxR9_VJzYrE4iICk3xOMcqq7/view?usp=sharing
Does this simulation result in reasonable output? Or did I screw up something?
