======================MODEL_NEEDS===========================
IS_and_NF doping levels in silicon define diode voltage of pn junction.
higher doped junction higher diode voltage
^ +5V
/_\

__
Apply / _ \ VBE = NF*(KT/q)*ln(I/Is)
100uA \/ \/ = 0.026*ln(I/Is)
 /\_/\
 \___/ Doping defines Is
V ______
 _ +
 ' NPN
___ Measure VBE
`> _

__
///
If NF =1 factor of ten at junction tranlates to 60mV.
^ gumbal  pooh
/_\ _
 _ / <== slope =1/2 <= IR DROP
IKF_  /
 ic / /
 / / ib slope =1 =1/NF Beta = ic/ib
 / /
 / _
/_ <== slope =1/NE NE =1.5 <= Leakage

_______\
VBE /
IS and NF terms define a transistor's Vbe under most conditions.
At high current TR drop causes deviation from diode equation
At low current leakage causes deviation from diode equation
BF bipolar transistor always consists to two pn junctions.
normal mode of operation, emitter base junction forward biased
while collector base junction is reverse biased.
In spice model,BF refer to beta in forward bias condition
This is always the emitter base junction.
^ +5V
/_\
_______
__ _____
Apply / _ \   Measure 100uA
1uA \/ \/  DVM  
 /\_/\   
 \___/ ______ V
V  
 _ hfe = Beta = 100uA/1uA =100
 ' NPN
___ Ratio Doping defines Bf
`>

__
///
BR In spice model, both pn junctions are measured and modeled.
BR VAR etc define behaviour of junction reverse biased
(collector base is on). Most these parameters except BR
have mild effects on transistor behaviour.
^ +5V
/_\
___
__
Apply / _ \ Measure Open Collector
1uA \/ \/
 /\_/\ ___
 \___/   + set by BR
V  ___
 _ 60mV
 ' NPN
___
`> 

__
///
When collector is open, both pn junction will be forward bias.
processes like VIP2 two junctions are close enough in doping
emitter bas junction close to collector base
that the open collect is almost at ground.
for most processing doping levels of collector base much lighter
collector base junction voltage typically 60mV less.
spice BR term can be adjusted to match silicon open collector.
VAF When measure beta, collector base voltage effect mag of beta.
^ +5V ^ 0> +5V
/_\ /_\
___ ______
__ _____
Apply / _ \   Measure 100uA
1uA \/ \/  DVM  
 /\_/\   
 \___/ ______ V
V  
 _ hfe = Beta = 100uA/1uA =100
 ' NPN
___ Ratio Doping defines Bf
`>

__
///
"Early voltage" can be though of as the inverse of tolerance of
collecter current verus collector voltage. A VAF of 100
means 1% increase in collector current over 1volt.
^ I collector
/_\


300uA _ ____ 3uA = ib
 /
 /_____ 2uA
 /
 /______ 1uA
/___________________\
Vcollector /
transistor curves slightly slope up
because as collector base reverse bias voltage is increased,
base gets slightly smaller
========================IKF_and_ISE_and_NE=================================
All transistors naturally have a point where athey are having trouble
putting out the power. When the current gets high enough, regions in
the base region have too much IR drop and start turning off. At
this point, the beta of the transistor starts dropping very quicky.
The spice term that models this is IKF. It is something like were
the beta begins to drop. Typically, the output transistors of an amplifier
need to be made large because of this effect.
NE defines low I beta drop off
100 ............................................
 . . . . . . . 
 . . . . . beta . 
 . . . beta . . . beta 
10.....................................:......
 . . . . . . . : . 
 . . beat . . . . : . 
 . . . . . . . : . 
1 ________beta_________________________:______
10pA .1nA 1nA 10nA .1unA 1uA 10uA .1mA: 1mA 10mA
:
^
/_\
IKF ____________
When you plot beta versus collector current, you will see the beta also
drop off at low collector current. In fact, this is the way you can
tell how well a transistor is processed. When the silicon has very
few defects, leakage currents are very low. Such a transistor will
still have a fair amount of beta at very low currents.
NE defines low I beta drop off
100 ............................................
 . . . . . . . 
 . . . . . beta . 
 . . . beta . . . beta 
10............................................
 . .beta. . . . . . 
 . . . . . . . . 
 . . . . . . . . 
1 ________beta________________________________
10pA .1nA 1nA 10nA .1unA 1uA 10uA .1mA 1mA 10mA
^
/_\
________ ISE and NE
In the spice model, the processing impacts on beta are modeled as the
ISE term which defines where the beta drops and the NE term which defines
how fast the beta drops.
========================RB_and_RBM_and_IRB_and_RE========================
As expected, all pn junctions has internal resistances. This will
be the main reason why a diode will not always increase 60mV per
factor of ten increase in emitter current. As current flows thru
the RB and RE spice terms shown below, there will of course be IR drop.
^ +5V
/_\

__
/ _ \ VBE = (KT/q)*ln(I/Is)
\/ \/
_ /\_/\
RB / \___/
_/\/ ______
 /\/ _ +
 ' NPN
_______ Measure VBE
`> RE _
__/\ ___
\/ __
///
The resistance at the base "Rb" drops as current current increases.
This happens around the same current where the beta also drops.
At higher currents, only the base regions which have low base resistance
tend to stay on. In spice, RB represent the base resistance at
low current, RBM is the base resistance at high current,
and IRB is the current were the base resistance begins to drop.
========================RC=================================
^ +5V
/_\
__________________
__ __
Apply / _ \ / _ \
100uA \/ \/ \/ \/  1mA
 /\_/\ /\_/\ 
 \___/ 60mV RC \___/ V
V  ____/\ ____
 _ \/ __
 ' NPN  
___ ___
`>

__
///
The collector region also has some resistance. The spice term is
RC. For the circuit above, if the RC value is 200 ohms, the collector
voltage should have 200mV of IR drop in the collector resistance
in addition to the 60mv will the collector voltage will be when open.
In this case, the collector voltage will be 260mV.
========================TF_and_CJE_and_IRF========================
The term FT for "F_sub_tau" is the way processing people like to
rate the speed of their transistors. FT is defined as { how high
does the frequency have to get before the AC beta drops to one}.
VIP2 npn FT about 1/(2*pi*TF)
10GHz .................................................
 . . . __ IKF .
 . . .  .
1GHz .....................................V..........
 Re*Cje . . 1/3ns . .
  . . .1/3ns .
100MHz ...................1/3ns.....1ns....1ns........
 V . 1ns . 1/3ns .
 1ns . . .
10MHz .....1/3n................................1ns....
 . . . .
1ns . . . .
1MHz _______________________________________________.
1uA 10uA 100uA 1mA 10 mA
A typical FT versus collector current is shown above. This FT terms
really is a measument of the "transient time" across the base region.
Heavy light Very Light
___________________________
 :+:Base: + :
 Emit :+: P : + : Collect
 N :+:n : + : N
 :+:nn : + :
 p:+:nnn : + :
 pp:+:nnnn: + :
______:__:____:____:_______
< >
holes electrons
The processing people try and make the thickness of the base region
as thin as possible so it takes an electron little time to travel
across it. The depletion region in the emitter base also defines
Cje. Since the doping is usually high, the thickness of the depletion
region is thin, and therefore the Emitter base Junction capacitance
cannot be ignored.
___
(C)
___

_____________
NPN __
Schematic / _ \
for FT \/ \/
/\_/\
\___/
___ emitter/base Ic 
(B)___________________  
___   __  V
__Cje __Cde \ / 
___ ___ _v_ 
100fF  If/Bf 
________________________

__
(E)
___
In the spice models, the TF for "forward transient time" is modeled
as a capacitor Cde. This "capacitor" increases as more current flow
through the emitter base junction, because the more forward biased a
pn junction is, the thinner is the emitter base junction. The
impedance of the emitter base junction also drops.
At low currents, Cde is small, the impedence of the emitter base
diode is large. The FT is defined in this region as were the junction
capacitance Cje shorts out the AC current which would otherwise go
into the emitter base diode. At high enough collector current, the Cde
is large enough and emitter base junction resistance low enough that
Cde and emitter base junction impedance dominate the speed. The spice
term TF defines Cde and therefore FT.
VIP2 npn FT about 1/(2*pi*TF)
10GHz .................................................
 . . . __ IKF .
 . . .  .
1GHz .....................................V..........
 Re*Cje . . 1/3ns . .
  . . .1/3ns .
100MHz ...................1/3ns.....1ns....1ns........
 V . 1ns . 1/3ns .
 1ns . . .
10MHz .....1/3n................................1ns....
 . . . .
1ns . . . .
1MHz _______________________________________________.
1uA 10uA 100uA 1mA 10 mA
When the beta starts to crash, the speed is also degraded as well.
From the processing people's point of view,the emitter base junction
capacacitance {Cje}, defines the speed at low currents. At higher currents,
speed is defined by the transient time { TF } through the base thickness.
And there will be a current level {IKF} above which both beta and speed are
degraded.
========================CJX_and_VJX_and_MJX_and_ETC========================
From the design engineers view point, there is a little more going
that needs to be considered. Every pn junction affect the high speed
performance. The full schematic is shown below.
___
(C)
___

________________________________________
  __ __Cjs
  / _ \ ___
  \/ \/ 
__Cjcx __Cjc /\_/\ __
___ ___ \___/ \sub/
___  Rbb  Ic  \ /
(B)__/\ _________________   V
___ \/   __  V (hidden)
__Cje __Cde \ / 
___ ___ _v_ 
100fF  If/Bf 
________________________

__
(E)
___
All of these junction capacitors also change over voltage. This is
where the VJX and MJX terms come into play.
The other speed parameters ar listed below. Various things like
collector voltage and current affect speed in other ways.
XCJC = fraction of cb cap connect to internal base node
PTF = excess phase at ft
^ Tff
/\
 /
______________/
__________________\
IKF /
IKF = Q_Bo/Tau_Bf Knee current
TF = 1/(2*PI*Ft)
TF = tf(1+xtf*(icc/(icc+itf))^2 *exp(vbc/1.44vtf))
ITF = high cuurent point for tf .01 vip2
VTF = voltage effecting tf 1.5 vip2
XTF = coeff of bias on tff 10 vip
FC = Fbias nonideal junccapcoeffi 0.5
F_tau CS80 npn vs Collector Voltage.
7GHz ................................................
 3 3 . . . .
 32 2 2 3 . . .
6GHz ..3........2.....3..............................
 2 . 2 3 . . .
 3 . 2 . 3 . .
5GHz .2....................2...........3.............
 2 . . 2 . .
3 . . . .
4GHz 3...............................................
 . . . .
 . . . .
5GHz _______________________________________________.
0 1mA 2mA 3mA
========================XTB_and_EG_and_XTI========================
Two major things change over temperature. The diode voltages all have
a large Temperature coeoffecient around 2mV/C_deg. This value needs to
be defined well in order to make voltage band gap reference. The
spice model parameter which defines that is XTI.
XTI defines TC of diode, expect 3/n
Model now uses XTI = 5.6
Is(T2) [ Is(T1)*(T2/T1)^(XTI) ]*...
...*[ exp( (q*Eg(300)/kT2)*(1T2/T1) ) ]
The Beta can also drop a factor of two at low temperatures. This is
modeled with the spice parameter XTB
BF(T2) = BF(T1)*(T2/T1)^XTB
XTB = 2 CS80_pnp 58% @(45C/27C)
2.4 = V3_pnp 53% 2.1= V2_pnp
Sometimes models have Temperature coeffecient values for all the
resistors as well. This may greatly slow down simulations while
not providing much improvement in accuracy. Is up to the designer.
========================Noise_Terms========================
The new 442 environment claims to have better noise features than
before. Given the crossover to the new environment, it may be worth
while to take another look at noise modeling.
I have included below a model file I am testing on the perfect 10
process to see what it takes to get the models and silicon to
give me the same results. This is not meant to knock the modeling
group. It seems like constant vigilance is required for processing.
And design has always played the row of QA anyway. I am trying to
get my model checkers to be a bit more easier to use, and I am
trying to make it easier to measure silicon as well. { Coyote }
The more eyes we can get looking at everything, the better.
... Don Sauer
^ gumbal  pooh
/_\ _
 _ / <== slope =1/2 <= IR DROP
IKF_  /
 ic / /
 / / ib slope =1 =1/NF Beta = ic/ib
 / /
 / _
/_ <== slope =1/NE NE =1.5 <= Leakage

_______\
VBE /
NAME=============DESCRIPTION_UNITS=========================LIMITS============
NMOS_IMPACT_ION Measure Substrate Current
This test measures to effect of
hot electrons which create substrate
current and degrade the lifetime of a MOS device.
___ Vds =5V
 2 
___ Ibs Measure Substrate Current
___ _ > ___
 3 ____________  1  This test measures to effect of
___   ___ hot electrons create substrate
> ____ current degrade lifetime of
__ __ a MOS device.
Vgs =0>5V  4  ///
___ Vbs =0V
EFFLN Measures the effective channel length as defined
by Poly CD and N+ source/drain of a minimum
Nchannel transistor.
VTNs are measured on each of the three
transistors; drain currents are measured with
the gate voltage set at VT+0.5, and drain at
0.1 V. A linear regression is performed using
the inverse of the drain currents vs. the drawn
L sizes (.8, 1.6, 3.2) and the xintercept is
obtained; this is DELTAL. This value is then
subtracted from the ideal minimum layout
dimension (0.8) to give EFFLN_8__B.
^ Ids
/\
 /
 /
________/_______\ Channel Length
^ /
__ Eff_L
Lamda = (L_eff +Delta_L)/L_eff = 1+Delta_L/Leff
Lamda = Delta_L/L_eff = Delta_L/(L_drawnLdef)
L_drawnLdef =Delta_L/(Lamda)
L_drawn_2 L_drawn_1 = Delta_L/(Lamda_2)Delta_L/(Lamda_1)
Delta_L =
(L_drawn_2 L_drawn_1)*Lamda_2*Lamda_1/(Lamda_1Lamda_2)
________________________________________________________
 L_eff=(L_drawn_2 L_drawn_1)*Lamda_2/(Lamda_1Lamda_2) 
________________________________________________________
NMOS_BODY_EFFECT IDS=1u Measure body effect [Vto(2.5V) Vto(0V)]
This test defines the effect the
bulk voltage has on the thresshold
voltage of a channel. Affects common
mode turn on voltages of switches.
Checks device sensitivity to P well biasing
and "body effect". The result from VTN40X_8_B
is compared to a new VT measurement with the
P well biased at 2.55 V. The delta between
the two is BEFFN_8__B, which formerly was
referred to as Mfactor.
___ ___
Vd = .1V (D) Vd = .1V (D)
___ ___
___ _ ___ _
Vgate_1 (G)________ (G)_________
___ Ý  ___  
> \/gnd > \/
"NMOS"  V "NMOS" V 2.55V
__ Vgate_2 __
(S) (S)
___ ___
______________________
Vgate_2 Vgate_1 =~ M 
______________________
NMOS_BREAKDOWN_V Measure Drain voltage needed for 1uA
This test defines the maximum supply
voltage for this process.
___
  Vds =0 > 20V
___ 
___ _ V IDS ___
 ____________  
___   ___
> ____
Vgs=0V __ __
  ///
___ Vbs =0V
NMOS_LEAKAGE Measure Ids at Vg =0
Measure turn off drain current
This test defines how much supply
current will flow in a logic device
which is in a DC state. (DC supply current)
___
  Vds = 5V
___ 
___ _ V IDS ___
 ____________  
___   ___
> ____
Vgs=0V __ __
  ///
___ Vbs =0V
NMOS_THRESHOLD__V Measure Ids vs Vgs to extrapolate Vt
Slope defined by Overdrive voltage
___ Vds =0.1V
 
___  IDS
___ _ V ___
 ____________  
___   ___
> ____
Vgs 0>3V __ __
  ///
___ Vbs =0V
^ Ids
/\
 / Ids = .1V*Beta*Vod
 /
_______________\ Vg
^ /
__ Vt
^ Ids
/\ ...Vgate_2
 / \...Vod
 /....Vgate_1 /
 /
_______________\ Vg
^ /
__ Vt
___ ___
Vd = .1V (D) Vd = .1V (D)
___ ___
___ Vg_1 _ ___ _
(G)____ Ids (G)____ 2Ids
___ >  ___ > 
"NMOS"  V "NMOS" V
__ Vg_2 __
(S) (S)
___ ___
Ids = .1V*Beta*Vod Ids*2= .1V*Beta*(Vod*2)
Vg_2 Vg_1 = Vod
__________________
Vth =~ Vg_1  Vod 
__________________
contact potential V (KT/q)*ln(A) 680mV = E+20 660mV= E+19
V_fermi_p (KT/q)*ln(N_accept/ni)
V_fermi_n (1)*(KT/q)*ln(N_donor/ni)
Breakdown
BVbco_V 95*(rho_epi_ohm_cm)^(.722)
BVceo_V BVbco_V/( (Beta_max+1)^(.25) )
BVbco_thickLimited_V 36*(w_um)^(.861)

mobility u_0*T^(3/2) due to lattice scattering
Resistance (ohms/square) versus doping
100 ................................................
 p . . . . . . 
n . . . . . . 
 n . . . . . . 
 . . . . . . 
10....n..p........................................
 . . . . . . 
 . p . . . . . 
 .n . . . . . 
 . . . . . . 
1..........n...p.................................
 . . . . . . 
 . . p. . . . 
 . .n . . . . 
 . . . . . . 
.1 ................n.......p......................
 . . . . . . 
 . . . n . . . 
 . . . . p . . 
 . . . n. . . 
.01...............................n..p.............
 . . . . . . 
 . . . . .n . 
 . . . . . p . 
 . . . . . p 
.001.........................................n......
 . . . . . . n 
 . . . . . . p n
 . . . . . . p 
 . . . . . . p
.0001________________________________________________
E14 E15 E16 E17 E18 E19 E20 E21
doping( /cm^3)
Mobility (cm/sec)*(cm/V) versus doping
.................................................
 . . . . . . 
 . . . . . . 
 . . . . . . 
e e . . . . . 
1000 .............e..................................
 . . . . . . 
 . . . . . . 
 . . e . . . 
 . . . . . . 
h...h...........................................
 . h . . . . . 
 . . h . .e . . 
 . . . . . . 
 . . . . . . 
100 .........................h.........e............
 . . . . . e e 
 . . . . . . 
 . . . . h . . 
 . . . . . h h 
................................................
 . . . . . . 
 . . . . . . 
 . . . . . . 
 . . . . . . 
10 ________________________________________________
E14 E15 E16 E17 E18 E19 E20 E21
doping( /cm^3)