BSIM4_U ( BSIM4 Universal Routine )

Application

This routine is a multitarget/geometry routine used to extract all kind of characteristics. There is the possibility to trace three different targets. This routine is based on full SMU definition. This definition could be done for 3 different targets grouped together in 4 different setup. It means that 12 different bias conditions can be defined. One device is associated with one setup therefore with one, two or three targets.

This routine has been especially written to measure the gate current for MOS transistors ( Figure 1 ). This routine is available for SOI and MOS technology.


Figure 1. One Target IG vs VG-VD Measurement Data Set.

 

For this both technologies the option macro modeling capability is available. Exchange, rubberband, fit and modeling are not available.

Data Acquisition

This routine has been written to work especially with HP4155/56 instruments. Each SMU can be fully configured. Each SMU can be either in current or in voltage. The current in each SMU can be limited. The number of section can be different to follow the target. The routine support six SMU maximum.

The Figure 2 shows a characteristics for four devices. This example shows all flexibility allowed by this routine.

 


Figure 2. Four devices with different number of targets each.

 

Four different setup have been defined, for each setup different targets are measured.

Setup 1 : 3 targets ( ID/VD-VG, ID/VG-VB, ID/VG-VD ) applied on the device ( 15u/15u ).

Setup 2 : 1 target ( ID/VG/VD ) applied on device ( 10u/0.8u ).

Setup 3 : 2 targets ( ID/VG-VD, IB/VG-VD ) applied on device ( 10u/0.7u ).

Setup 4 : 1 target ( IS/VD-VG ) applied on device ( 10u/0.65u ).

Measurement Setup

The DC MEASUREMENT SETUP shows two SMU by two SMU. Each SMU can be fully configured. You can measure only one SMU each time.

The parameters will depend on the SMU configuration. If the SMU1 is defined as VAR1 and is connected with the Drain then the parameters displayed will be Vd start, Vd stop, Vd step, Vd points. Whereas if the variable is VAR’1 the parameters displayed will be Vd offset and Vd ratio.

In this example

Vd is defined as sweep order 1 from 0 to 5 V with a step of 0.102. The sweep is linear and done on voltage source. The current corresponding to Vd is measured, so Id is measured.

Vg is defined as the second sweep from 0 to 5 V with 6 points ( therefore 6 sections in the curve ).

In the section “Measurement variables” all meaning will be defined.

To complete device polarization, the SMU3 is used as a voltage source with the constant value 0 V , and SMU4 is used as a voltage source with the constant value 0.1 V for the bulk node


In the case of polarization, the measured current will be ID = f(VDS, VGS ) curve.

The following is used for macro modeling or SOI technology when we need more than four SMU.

 

Measurement Variables

The Table 1 shows the different measurement variables with their possible values. All these variables correspond to one SMU. We call here Y the mode ( current of voltage) and x the electrode name (Drain, Gate etc...).

VAR1’ is calculated following the equation: VAR1’ = ratio*VAR1 + offset.

Each SMU can be configured in voltage or current:“Mode”. If you want to sweep in voltage you tape 1 and 2 in current. For the measure it’s the same thing.

The “sweep mode” is used for the main and the second sweep. “Measure” is used to select which SMU you want to use for the measurement.

Number

Name Description
1/2 SMU_no SMU number 1 to 6.
3/4 Mode SMU mode: 1='V', 2='I', 3='COM'.
5/6 Sweep Sweep mode: <2=linear, 3=log10, 4=log25, 5=log50.
7/8 Compl. Compliance for the SMU.
9/10 Meas. 1=the SMU is measured. 0=the SMU is not measured.
11/12 Sweep order 1=VAR1, 2=VAR2, 3=CONST, 4=VAR1', 5=Not Used.
13/14 Yx start Start value of the electrode x sweep range ( for VAR1 or VAR2 ). A constant for CONST. Offset value for VAR1'.
15/16 Yx stop Stop value of the electrode x sweep range ( for VAR1, VAR1'or VAR2). A constant if "Sweep order=3".
17/18 Yx points Number of points for the sweep ( for VAR1 or VAR2 ).
Ratio value for VAR1'.
19/20 Yx step Step value. For VAR1 or VAR2. step = ( stop - start ) / ( points -1 ).
21/22 IDvsVDS format IDvsVGS format If "IDvsVDS format"or "IDvsVGS format"is equal to 1 then the current target will be convert to ALL_DC format in the log file.

Table 1. Measurement Variables




The “Sweep order” allows to select between the main sweep (VAR1), the second sweep (VAR2,VAR1’) and a constant. The instrument can accept VAR1, VAR1+VAR2 and VAR1+VAR1'.

IDvsVDS format, IDvsVGS format allows to write the log file in the ALL_DC format. Conversely the routine can read log files in ALL_DC format.



Figure 3. The Universal Measurement Setup Screen for SMU1-2 page.

 


Figure 4. The Universal Measurement Setup Screen for SMU3-4 page.

 

The Table 2 shows an example of measurement variables configuration ( Figures 3 and 4) in order to measure an Id/Vd-Vg. In the case where the SMU are configured as following SMU1=Vd, SMU2=Vg, SMU3=Vs , SMU4=Vb , SMU5=V#5,SMU6=V#6.

SMU5 and SMU6 are not used.

SMU1-2
SMU1-2
SMU3-4
SMU3-4
SMU5-6
SMU5-6
SMU(Vd) = 1 SMU(Vg) = 2 SMU(Vs) = 3 SMU(Vb) = 4 SMU(V#5) = 5 SMU(V#6) = 6
Mode = 1 Mode = 1 Mode = 1 Mode = 1
Sweep = 1 Sweep = 1
Compl. = 1E-3 Compl. = 1E-3 Compl. = 1E-3 Compl. = 1E-3
Meas. = 1 Meas. = 0 Meas. = 0 Meas. = 0
Sweep order = 1 Sweep order = 2 Sweep order = 3 Sweep order = 3 Sweep order = 5 Sweep order = 5
Vd start = 0 Vg start = 0 Vs = 0 Vb = 0.1
Vd stop = 5 Vg stop = 5
Vd points = 50 Vg points = 6
Vd step = 0.102 Vg step = 1
IDvsVDS forma = 0 IDvsVGS forma = 0 IDvsVDS forma = 0 IDvsVGS forma = 0 IDvsVDS forma = 0 IDvsVGS forma = 0

Table 2. ID vs VD-VG measurement variables configuration.

Environment

In the DC MEASUREMENT SCREEN there’s a button for the target number selection and for the target selection. For each setup you can select up to 3 targets. The SMU x-y button allows to select SMU page. Each SMU page contain two SMU definitions. The HARDWARE def. button allows to display the HARDWARE CONFIGURATION SCREEN.

In the Setup and Result Screen the attributes button allows to change the Multiroutine Depth. The Multiroutine Depth is the number of target in which you can change the Y scale. The Y scale is changed in the Routine Cntl/Multiple Select.

In the DATA SETUP SCREEN the target number is selected with a button in the right. In the SPAYN DATA SCREEN a button allows to select which target to use for the used point. In the OUTPUT LOG FILE SCREEN the Log X data option named TABLE allows to write in log file uniquely the SMU used and the SMU measured. The TABLE.UNIV option allows to get all currents and voltages during the measurement ( SMU 1 to 6 ).

 

Local Optimization

The local optimization is available for multi target/geometry capability. The user can select in the TARGET SELECTION SCREEN which target he want to optimize. In the TARGET SELECTION SCREEN for each row a button allows to select which target to optimize. This selection will be available for all devices chosen in the geometry button. So if you want to optimize target 1 of device 1 and target 2 of device 1 you must use two rows in the TARGET SELECTION SCREEN. Also, be careful if you select two devices with a different target number.


Global Optimization

The global optimization is available for multitarget/geometry capability. The user create a box on the target he wants to optimize. Example Figure 6 only two target is optimized. If there’s no box nothing will be optimize. To optimize an entire target you must create a box including all curves.

 


Figure 5. Four devices with different number of target
curves Simulated Using Simulated Option.

 


Figure 6. Four devices with different number of targets.
Curves, Simulated Using the Simulate Option.

 

 

Macro Modeling

Macro modeling is available for both SOI and MOS technologies.


Parameter Labels are defined with the Parameter Definition statement .PARAM in the .net file. Parameter Labels can be defined as constant numerical values or as an equations defined with constant numerical and/or previously specified Parameter Labels. Equations must be enclosed by single quotes (') or normalized delimit character (External SPICE dependent). Once defined, a Parameter Labels can be used in the netlist or model card when a constant numerical value is expected.

For the MOS technology the following parameters are indispensable to define all electrodes. In the case where the macro model is defined with six pads.

 

Example

.PARAM Vd_VAL = 0.000000e+00
.PARAM Vg_VAL = 1.100000e-01
.PARAM Vs_VAL = 1.000000e+00
.PARAM Vb_VAL = 0.00000e+00
.PARAM V#5_VAL = 0.000000e+00
.PARAM V#6_VAL = 0.000000e+00


For the SOI technology

Example

.PARAM Vd_VAL = 0.0000000e+00
.PARAM Vg_VAL = 0.0000000e+00
.PARAM Vs_VAL = 0.0000000e+00
.PARAM Vbg_VAL = 0.0000000e+0
.PARAM Vbd_VAL = 0.0000000e+00
.PARAM V#6_VAL = 0.0000000e+00

 

Power Sources
Power Sources are available to drive the macro-device.

 

G Voltage Controlled Current Source
H Current Controlled Voltage Source
I Constant Current Source
V Constant Voltage Source

 

For the MOS technology the power sources are defined as following.

Vd 1 0 'Vd_VAL'
Vg 2 0 'Vg_VA'
Vs 3 0 'Vs_VA'
Vb 4 0 'Vb_VA'
V#5 4 0 'V#5_VA'
V#6 5 0'’V#6_VAL'

 

For the MOS technology the power sources are defined as following.

Vd 1 0 'Vd_VAL’
Vg 2 0 'Vg_VAL’
Vs 3 0 'Vs_VAL’
Vb 4 0 'Vb_VAL’
V#5 4 0 'V#5_VAL’
V#6 5 0 'V#6_VAL’


For the SOI technology.

Vd 1 0 'Vd_VAL’
Vg 2 0 'Vg_VAL’
Vs 3 0 'Vs_VAL’
Vbg 4 0 'Vbg_VAL’
Vbd 5 0 'Vbd_VAL’
V#6 5 0 'V#6_VAL’

Control Statements File
The format of the Control Statements File for the macro-model must match the routine used to measure the macro-device. The power source names used in the circuit must match the power sources name in the Control Statement File. The values of the power source sweep and step parameters are not important since UTMOST will substitute them with the values stored in the Measurement Screen relative to the routine used. It is essential that the measurement and simulation bias conditions be identical.

Following power sources defined previously the control statement for MOS can be:

 

Example

*UTMOST INTERFACE
.DC Vd 0 5.000 0.100 Vg 1.0 5.0 1.0
.PRINT DC I(Vd)

For SOI technology:

Example

*UTMOST INTERFACE
.DC Vd 0 5.000 0.100 Vg 1.0 5.0 1.0
.PRINT DC I(Vbd)

 

Conclusion

The new BSIM_U routine permits all the measurements for device characteristic measurement. This routine allows the parameter optimization corresponding to the gate current using Global and Local optimization. Based on full SMU definition, this routine is able to combine different kind of characteristics together, for characterization and parameter optimization.