New SOI UTMOST Module
Introduction
Bulk CMOS is currently the dominant technology for VLSI integrated circuits but its scaling constraints pose ever greater as device geometries shrink. Thus, the search for a suitable replacement has begun, and SiliconOnInsulator (SOI) technology seems to become the most attractive candidate for a suitable VLSI/CMOS technology.
The SOI technology differs significantly from the bulk technology due to the burried oxide. Because of this specific structure, SOI MOSFETs exhibit many anomalous static and dynamic effects which can be attributed to either the floating body or to self heating. Consequently, in addition to the usual Bulk MOSFET, several other characteristics must be observed to characterize correctly and accurately SOI devices. SOI utmost module has been improved accordingly to these criteria, and is presented in this article.
SOI Module Specificities
Number of Terminals
SOI devices are commonly designed with 4 terminals : Drain,
Gate, Source and BackGate terminals. It can also be designed with
a fifth terminal in order to access the internal Body (equivalent
to MOS Substrate terminal). Users can switch between 4 and 5 terminals
devices through the "# of Terminals" button of the Common Control
Screen.
The SMU Definition Screen will be so modified accordingly to the
number of terminals selected. For example, in the HP4145 case and
for 5 terminal devices, the BackGate terminal will be applied on
the VS1 Unit. For the HP4156, the user will be able to choose between
SMU5 (if he can use this SMU) or VS1.
Figure 1. SMU Definition Screens for HP4145 and HP4156.
The general syntax to define a SOI device in UTMOST, is:

MXX ND NG NS NBG (NB) MNAME (L=Lavlue) (W=Wvalue)
where ND is the Drain node, NG is the Gate node, NS is the Source node, NBG is the BackGate node, and NB is the optional Body node. This Body node should be present in case of body contacted devices. MNAME is the model name while L and W are respectively the length and width of the device.
Common Routines
ID/VDVG Routine
This routine comes from the well known ID/VDVG MOS routine, and
has been adapted to the SOI Module allowing users to measure, simulate
and optimize Output characteristics. Rubberband and modeling are
also available. The drain voltage is swept over a defined voltage
range for a set of VG values. BackGate (and Body if accessible)
are kept to constant values.
The DC Measurement Screen variables are described
below. The number of VG steps is defined in the Measurement Section
field now available in both DC Measurement Screen and Routine Control
Screen.
VDS_start  Starting value of the Drain voltage sweep range. 
VDS_stop  Stop value of the Drain voltage range. 
points  Number of sweep data points. 
VGS_start  Starting value of Gate voltage. 
VGS_stop  Step value of the Gate voltage. 
VBG_or_Body  Constant voltage applied to BackGate (if Stepflag=0) or to Bodycontact (if Stepflag=1). 
V_constant  Constant voltage applied to Bodycontact (if Stepflag=0) or to BackGate (if Stepflag=1); only used with 5 terminals. 
compl_smu(A)  SMU current compliances. 
wait  Wait time in microseconds, between measurements 
Stepflag  BackGateBody switch flag. 
Figure 2. Typical ID/VDVG Measured Data Set.
SOI characteristic in continuous line, and SOI
with BodyContact in dashed line.
ID/VGVB Routine
This routine also comes from the well know ID/VGVB MOS routine.
It is dedicated to the transcharacteristic analysis. Measurement,
simulation, optimization, rubberband and modeling are available
for this routine. The Gate voltage is swept over a defined range
for a set of BackGate (or Body) values. In case of 5 terminals Body
(or BackGate) is kept to a constant value. Drain is kept to a constant
value too.
The DC Measurement Screen variables are described
below. The number of VBG (or VBody) steps is defined in the Measurement
Section field now available in both DC Measurement Screen and Routine
Control Screen.
VGS_start  Starting value of the Gate voltage sweep range. 
VGS_stop  Stop value of the Gate voltage range. 
points  Number of sweep data points. 
VD  Constant Drain voltage. 
V_start  Starting value for the stepped voltage (Body if Stepflag=1, BackGate if Stepflag=0). 
V_step  Step value for the stepped voltage Body if Stepflag=1, BackGate if Stepflag=0). 
V_constant  Constant voltage applied to BackGate (if Stepflag=1)or to Body (if Stepflag=0 voltage ; only used with 5 terminals. 
compl_smu(A)  SMU current compliances. 
wait  Wait time in microseconds, between measurements. 
Stepflag  Body voltage is stepped if 1, else BackGate voltage is stepped; only active with 5 terminals. 
Figure 3. Typical SOI ID(VG) characteristic for several
VBackGate (4 terminals) with markers and dashed
lines. Usual ID/VG characteristic for several VBody
(5 terminals, stepflag=1) in continuous lines.
ALL_DC Routine
Identical to the MOS Module, the ALL_DC routine is a multigeometry
and multicharacteristic routine. This routine will allow the user
to display both ID/VGVB and ID/VDVG curves for several devices
on the same plot. This is a powerful routine, which will be strongly
recommended for multiple optimizations. This routine is available
for measurement, simulation, optimization, rubberband and modeling
features.
The DC Measurement Screen variables are described
below. The number of VG and VBG (or VBody) steps are defined in
the Measurement Section field now available in both DC Measurement
Screen and Routine Control Screen.
VD_start_vd  Starting value for the Drain voltage sweep (ID/VD curves). 
VD_stop_vd  Stop value for the Drain voltage range (ID/VD curves). 
VG_start_vd  Starting value of the Gate voltage step (ID/VD curves). 
VG_step_vd  Step value for the Gate voltage (ID/VD curves). 
V_start_vd  Starting value of the BackGate (or Body) voltage second step (ID/VD curves). 
V_step_vd  Step value for the BackGate (or Body) voltage second step (ID/VD curves). 
V_points_vd  Number of BackGate (or Body) step points (ID/VD curves). 
V_const_vd  Constant Body (or BackGate) voltage value ; only used with 5 terminals (ID/VD curves). 
VG_start_vg  Starting value for the Gate voltage sweep (ID/VG curves). 
VG_stop_vg  Stop value for the Gate voltage range (ID/VG curves). 
VD_vg  Constant Drain voltage value (ID/VG curve). 
V_start_vg  Starting value for the BackGate (or Body) voltage step (ID/VG curves). 
V_step_vg  Step value for the BackGate (or Body) voltage step (ID/VG curves). 
V_const_vg  Constant Body (or BackGate) voltage value ; only used with 5 terminals (ID/VG curves). 
points  Number of sweep data points. 
ALL0,VD1,VG2  If 0, both ID/VD and ID/VG curves are measured. If 1, only
ID/VD curves are measured. If 2, only ID/VG curves are measured. 
compl_smu(A)  SMU current compliances. 
wait  Wait time in microseconds, between measurements. 
Stepflag  If 0, V_start,step,.._vd(vg) are applied on BackGate, and
V_const_vd(vg) are applied on Body. If 1, V_start,step,.._vd(vg) are applied on Body, and V_const_vd(vg) are applied on BackGate. Only used with 5 terminals. 
Figure 4.Typical ALL_DC plot, with ID/VD and gds
targets for a partially depleted SOI device.
To avoid confusion between BackGate and Body value, variable definitions
can be given as in Table 1.
Measurement variables  4 terminals  5 terminals  
stepflag=0  stepflag=1  
V_start_vd, V_step_vd, V_points_vd  VBackGate @ID/VD  VBackGate @ID/VD  VExtBody @ID/VD 
V_const_vd  Not Used  VExtBody @ID/VD  VBackGate @ID/VD 
V_start_vg, V_stop_vg  VBackGate @ID/VD  VBackGate @ID/VG  VExtBody @ID/VG 
V_const_vg  Not Used  VExtBody @ID/VG  VBackGate @ID/VG 
Table 1.
BSIM3_MG routine
BSIM3_MG routine derived from the MOS module and has been adapted
for the SOI module. As for the MOS module, this routine will manage
four characteristics: ID/VDVG with 0V on BackGate (or Body), ID/VGVB
for low VD, ID/VDVG for high BackGate (or Body) bias, and ID/VGVB
for high VD. If this routine is used with 5 terminals and stepflag=1,
curves will be obtained as for a MOS device. All BSIM3 model parameters,
as can be done in the MOS module, will be extracted.
The DC Measurement Screen is described below.
The number of VG steps is given through the #_of_vgsteps variable,
and the number of VBG (or VBody) steps is given through the #_of_vbsteps
variable.
VGS_start_vg  Starting value for the Gate voltage sweep (ID/VG curves). 
VGS_stop_vg  Stop value for the Gate voltage range (ID/VG curves). 
VDS_low_vg  Low constant Drain voltage for the linear region (ID/VG curves). 
VDS_high_vg  High constant Drain voltage for the saturation region (ID/VG curves). 
VDS_start_vd  Starting value for the Drain voltage sweep (ID/VD curves). 
VDS_stop_vd  Stop value for the Drain voltage range (ID/VD curves). 
VGS_strt1_vd  Starting value of the Gate voltage step (ID/VD curves with VBG(or VBody)=0V) ; value calculated from extracted threshold voltage and VGS_strt_off. 
VGS_strt2_vd  Starting value of the Gate voltage step (ID/VD curves with VBG(or VBody)=V_stop_vd) ; value calculated from extracted threshold voltage and VGS_strt_off. 
VGS_strt_off  Offset voltage used to determine VGS_strt1_vd and VGS_strt2_vd values. 
V_stop_vd  Maximum BackGate (or Body) voltage (ID/VD curves). 
V_const_vd  Constant Body (or BackGate) voltage (ID/VD curves) ; only used with 5 terminals. 
compl_smu(A)  SMU current compliances. 
points  Number of sweep data points. 
V_stop_vg  Maximum BackGate (or Body) step voltage (ID/VG curves). 
V_const_vg  Constant Body (or BackGate) voltage (ID/VG curves). 
wait  Wait time in microseconds, between measurements. 
#_of_vgsteps  Number of VG steps (ID/VD curves). 
#_of_vbsteps  Number of VBG (or VBody) steps (ID/VG curves). 
Stepflag  If 0, V_stop_vd(vg) are applied on Backgate ; V_const_vd(vg) are applied on Body. If 1, V_stop_vd(vg) are applied on Body ; V_const_vd(vg) are applied on BackGate. Only used with 5 terminals. 
Figure 5. Example of BSIM3_MG measurement
for a long and large device. Case 5 terminals,
and Stepflag=1.
To avoid confusion between BackGate and Body value, varaible definitions can be given as in Table 2.
Measurement variables  4 terminals  5 terminals  
stepflag=0  stepflag=1  
V_stop_vd  VBackGate @ID/VD  VBackGate @ID/VD  VExtBody @ID/VD 
V_const_vd  Not Used  VExtBody @ID/VD  VBackGate @ID/VD 
V_stop_vg  VBackGate @ID/VD  VBackGate @ID/VG  VExtBody @ID/VG 
V_const_vg  Not Used  VExtBody @ID/VG  VBackGate @ID/VG 
#_of_vgsteps  VGate Steps @ID/VD  
#_of_vdsteps  VBackGate Steps @ID/VG  VBackGate Steps @ID/VG  VExtBody Steps @ID/VG 
Table 2.
The extraction part of this routine is derived from the MOS module,
and allows the user to extract the whole MOS BSIM3 model parameters
of the BSIM3SOI model.
Currently, this routine is only able to extract low VD model parameters.
AL_IDVGD Routine
This last routine also comes from the MOS module. This is a new
multigeometry routine, which allows users to measure the drain
current over a defined gate sweep voltage for several drain voltages.
A second step can be applied on the BackGate with 4 terminal devices,
and on the Body with 5 terminal devices. This routine allows the
measurement, simulation, optimization, rubberband and modeling features.
The DC Measurement Screen is described below.
The number of VD steps is defined in the Measurement Section field.
VGS_start  Starting value of the Gate voltage sweep range. 
VGS_stop  Stop value of the Gate voltage range. 
points  Number of sweep data points. 
VD_start  Starting value of the Drain step voltage. 
VD_step  Step value of the Drain voltage. 
VB_start 
Starting Backgate voltage value in case of 4
terminals. Starting Body voltage value in case of 5 terminals. 
VB_step 
Step BackGate voltage value in case of 4 terminals.
Step Body voltage value in case of 5 terminals. 
VB_points  Defines the number of BackGate (or Body) bias points. 
VB5_cst  BackGate constant voltage ; only used with 5 terminals. 
VS  Constant Source voltage. 
complsdb(A)  SMU current compliances. 
wait  Wait time in microseconds, between measurements. 
IDS_low_cut  Drain low current limit to filter noisy data points. 
Figure 6. Typical ID/VGVD curves for
partially depleted SOI devices.
IB/VG_MG Routine
This routine stems from the well known ALL_ISUB MOS routine, and
is dedicated to characterize the Impact Ionisation current. As for
ALL_ISUB, it is a multigeometry routine. Measurement, simulation,
optimization, rubberband and modeling are available. Internal Body
current is measured over a defined gate voltage sweep range, for
several drain constant steps, and eventually for various second
Body values. During all measurements, source and backgate are kept
to constant values.
The DC Measurement Screen variables are described
below. The number of VD steps is defined in the Measurement Section
field.
VGS_start  Starting value of the Gate voltage sweep range. 
VGS_stop  Stop value of the Gate voltage range. 
VDS_start  Stating value of the Drain step voltage. 
VDS_step  Step value of the Drain voltage. 
V_start  Starting value of the Body second step voltage. 
V_step  Step Body voltage value for the second step. 
V_points  Number of Body voltage steps. 
VBackGate  Constant Backgate voltage value. 
points  Number of sweep data points. 
wait  Wait time in microseconds, between measurements. 
compl_smu(A)  SMU current compliances. 
VS  Constant Source voltage. 
compl_vs(A)  Current compliance for voltage sources. 
Figure 7. Typical Impact Ionisation current
characteristic for several devices and several Body bias.
IB/VB_MG routine
This new routine is dedicated to measure the well known SOI IB(VB)
characteristic. This characteristic represents the current flowing
through both DrainBody and SourceBody diodes. The principle of
this measurement is to fix source, drain and BackGate voltages,
sweep the Body voltage for several gate bias, and measure the Body
current. Also, a classical diode characteristic will be obtained.
This routine is a multigeometry routine, in which measurement,
simulation, optimization, rubberband and modeling are available.
The DC Measurement Screen variables are described below. The number of VG steps are defined in the Measurement Section field.
VB_start  Starting value for the Body voltage sweep range. 
VB_stop  Stop value for the Body voltage range. 
VG_start  Starting value for the Gate step voltage. 
VG_step  Step value for the Gate voltage. 
points  Number of sweep data points. 
VDcst  Constant Drain voltage value. 
VScst  Constant Source voltage value. 
VBGcst  Constant Backgate voltage value. 
compl_smu(A)  SMU current compliances. 
compl_vs(A)  Current compliance for the voltage sources. 
wait  Wait time in microseconds, between measurements. 
Figure 8. Typical IB(VB) characteristic,
for two devices.
IC/VCE Routine
This new routine is dedicated for parasitc DrainBodySource Bipolar
device characterization. The aim of this routine is to measure the
output characteristic of this parasitic bipolar, such as IC(VCE)
characteristic for a real Bipolar device. To adapt this for the
parasitic bipolar of the SOI device, the drain current for a defined
drain sweep voltage should be measured, for several Body bias. We
can consider the drain as the collector, the source as the emitter,
and the body as the base of an equivalent real bipolar device. This
routine is a multigeometry routine, for which measurement, simulation,
optimization, rubberband and modeling features are available.
The DC Measurement Screen variables are described
below. The number of VB steps is defined in the Measurement Section
field.
VD_start  Starting value for the Drain voltage sweep range. 
VD_stop  Stop value for the Drain voltage range. 
VB_start  Starting value of the step Body voltage. 
VB_step  Step voltage value for the Body steps. 
points  Number of sweep data points. 
VGcst  Constant Gate voltage value. 
VScst  Constant Source voltage value. 
VBGcst  Constant BackGate voltage value. 
compl_smu(A)  SMU current compliances. 
compl_vs(A)  Current compliance for voltage sources. 
wait  Wait time in microseconds, between measurements. 
Figure 9. Typical SOI Parasitic Bipolar Output
characteristics, for two devices.
DIODE Routine
This routine is again a completely new routine. Its origin comes
from the IB/VB_MG routine, in which we measured the current flowing
through both DrainBody and SourceBody diodes. The objective of
this Diode routine is to isolate the current of one diode, shortcutting
the second one. We can measure the DrainBody (respectivelly SourceBody)
diode current for a defined Body voltage swep range. The principle
simple. The same voltage on both Body and Source (respectivelly
Drain) terminals; needs to be applied so that the SourceBody (respectivelly
DrainBody) diode will not be biased, preventing current from going
through this diode. For measurement, the principle is to use the
VAR1' functionnality of the HP4145 and HP4156 instruments. During
all measurements, BackGate and Drain (respectivelly Source) are
kept to constant values. This measurement can be repeated for several
gate voltages, in order to eventually includes the effect of gate
biasing on this characterisic. In terms of simulation, the nodes
for Body and Source (respectivelly Drain) should be the same. This
routine is again a multigeometry routine, with measurement, simulation,
optimization, rubberband and modelling features available.
The DC Measurement Screen variables are described
below. The number of VG steps is defined in the Measurement Section
field.
VB_start  Starting value for the Body voltage sweep range. 
VB_stop  Stop value for the Body voltage range. 
VG_start  Starting value of the step Gate voltage. 
VG_step  Step value for the Gate voltage. 
points  Number of sweep data points. 
VDcst  Constant Drain voltage ; only used if VAR1'? D=0S=1 is set to 1. 
VScst  Constant Source voltage ; only used if VAR1'?D=0S=1 is set to 0. 
VBGcst  Constant BackGate voltage. 
compl_smu(A)  SMU current compliances. 
compl_vs(A)  Current compliance for voltage sources. 
VAR1'  D=0S=1 If 0, VAR1', is applied on Drain, and SourceBody diode current is measured. If 1, VAR1', is applied on Source, and DrainBody diode current is measured. 
Figure 10. Typical DrainBody and SourceBody diode current characteristics.
Gummel Routine
This is a new routine dedicated, as is the IC/VCE routine, to the
parasitic bipolar characterization. In order to characterize completely
this bipolar, in addition to the output characteristic, the Gummel
characteristic should be analyzed. For a classical bipolar device,
this characteristic is composed of the Base and Collector curves
versus a Base voltage sweep. For this SOI module, the equivalent
is to measure the Body (for Base) and Drain (for Collector) currents
for a defined Body (for Base) sweep voltage range. During all measurements,
Drain, Source, Gate and BackGate are kept to constant values. As
all other routines, this is a multigeometry routine, in which measurement,
simulation, optimization, rubberband and modeling features are active.
The DC Measurement Screen is described below.
VB_start  Starting value for the Body voltage sweep range. 
VB_start  Starting value for the Body voltage sweep range. 
VB_stop  Stop value for the Body voltage range. 
VDcst  Constant Drain voltage value. 
VScst  Constant Source voltage value. 
VBGcst  Constant BackGate voltage value. 
points  Number of sweep data points. 
compl_smu(A)  SMU current compliances. 
compl_vs(A)  Current compliance for voltage sources. 
wait  Wait time in microseconds, between measurements. 
Conclusion
This new SOI module is now available in Utmost
III, and in addition to the various SOI models of SmartSpice,
will allow our users to extract a full scalable DC SOI model. The
main characteristics are now available in UTMOST,
all available in measurement, simulation and optimization, to allow
maximum flexibility for users. Rubberband, Modeling and Log Files
features are also available.