• Analog Custom Design & Analysis Examples

opt_ex09 : BSIM3 MOSFET Model Extraction

Requires: Utmost IV, SmartSpice, SmartView

Minimum Versions: Utmost IV 1.10.6.R, SmartSpice 4.10.2.R, SmartView 2.28.2.R

This example describes how to extract a standard BSIM3v3 model. To extract a model which is scalable with geometry, multiple different device sizes must be included. In this example, nine device geometries are included.

The project file opt_ex09.prj and the data file opt_ex09.uds for this example should be loaded into your database. When opened, the project will look as shown in opt_ex09_project.png .

The optimization sequence, which fully automates the extraction of this BSIM3v3 model, has nine sections. The objective of each section is to isolate a device characteristic and then to optimize only those model parameters which account for this device behavior.

Section 1 : idvglin_large_rtp

This section optimizes the parameters for wide and long channel devices. The data in this section is the drain current versus gate voltage characteristic in the linear region and at room temperature. The following model parameters are extracted.

  • VTH0 Threshold voltage @Vb=0 for large L
  • U0 Mobility at nominal temperature
  • UA First-order mobility degradation coefficient
  • UB Second-order mobility degradation coefficient
  • K1 First-order body effect coefficient
  • K2 Second-order body effect coefficient
  • UC Body-effect of mobility degradation coefficient
  • NFACTOR Subthreshold swing factor
  • VOFF Offset voltage in the subthreshold region at large W and L

After this step has been completed, the fit to measured data will be as shown in opt_ex09_01.png .

Section 2: idvglin_larray_rtp

In this section, the parameters for short channel effect are optimized using devices of multiple lengths and wide channel value. The following model parameters are extracted.

  • LINT Length offset fitting parameter form I-V without bias
  • DVT0 First coefficient of short-channel effect on Vth
  • DVT1 Second coefficient of short-channel effect on Vth
  • NLX Lateral non-uniform doping coefficient
  • RDSW Width coefficient of parasitic resistance
  • DVT2 Body-bias coefficient of short-channel effect on Vth
  • PRWG Gate bias coefficient of RDSW
  • PRWB Body bias coefficient of RDSW

After this step has been completed, the fit to measured data will be as shown in opt_ex09_02.png .

Section 3 : idvglin_warray_rtp

The narrow width parameters are now extracted using data from devices with various channel widths and with a long channel value. The following model parameters are extracted.

  • WINT Width offset fitting parameter form I-V without bias
  • K3 Narrow width coefficient
  • W0 Narrow width parameter
  • K3B Body effect coefficient of K3

After this step has been completed, the fit to measured data will be as shown in opt_ex09_03.png .

Section 4 : idvglin_small_rtp

This section extracts parameters from devices with both short and narrow channels. The binning parameters PVTH0, PK1, PK2, PUA and PRDSW are extracted. These parameters are the variation of VTH0, K1, K2, UA and RDSW for short and narrow devices.

After this step has been completed, the fit to measured data will be as shown in opt_ex09_04.png .

At this point, the fit to the measured data should be verified and if necessary, steps 1 through 4 should be repeated until the fit to all measured data is good.

Section 5 : idvdlow_all_rtp

The first 4 sections concentrated only on the linear regions drain current versus gate voltage for each of the different geometries. This section will use the saturation region drain current versus drain voltage data for all device geometries. The following parameters are optimized.

  • A0 Bulk charge effect coefficient for channel length
  • AGS Gate bias coefficient of the bulk
  • VSAT Saturation velocity at nominal temperature
  • PCLM Channel length modulation parameter
  • PDIBLC1 First output resistance DIBL effect correction parameter
  • ETA0 DIBL coefficient in subthreshold region
  • PVAG Gate dependence of Early voltage
  • B0 Bulk charge effect for narrow width
  • B1 Bulk charge effect width offset
  • PVSAT VSAT variation for short and narrow devices

After this step has been completed, the fit to measured data will be as shown in opt_ex09_05.png .

Section 6 : idvdhigh_all_rtp

This section extracts parameters responsible for the saturation drain current versus drain voltage characteristics with back bias. The following parameters are optimized.

  • KETA Body-bias coefficient of the bulk charge effect
  • LKETA KETA variation for short devices
  • WKETA KETA variation for narrow devices
  • PKETA KETA variatino for short and narrow devices
  • ETAB Body-bias coefficient for the subthreshold DIBL effect
  • PDIBLCB Body effect coefficient of DIBL correction parameters

After this step has been completed, the fit to measured data will be as shown in opt_ex09_06.png .

This completes the room temperature DC model, the following sections will deal with the temperature model.

Section 7: idvglin_large_temp

This section extracts the model parameters for the large geometry drain current versus gate voltage linear temperature measurements. The following parameters are optimized.

  • KT1 Temperature coefficient for threshold voltage
  • KT2 Body-bias coefficient of the Vth temperature effect
  • UTE Mobility temperature exponent
  • UA1 Temperature coefficient for UA
  • UB1 Temperature coefficient for UB
  • UC1 Temperature coefficient for UC

After this step has been completed, the fit to measured data will be as shown in opt_ex09_07.png .

Section 8 : idvglin_all_temp

Now we select all of the device geometries at temperature for the linear drain current versus gate voltage characteristics and optimize the following parameters.

  • KT1L Channel length sensitivity of temperature coefficient for threshold voltage
  • PRT Temperature coefficient for RDSW
  • LUTE UTE variation for short devices
  • LUA1 UA1 variation for short devices
  • PUTE UTE variation for short and narrow devices
  • PUA1 UA1 variation for short and narrow devices

After this step has been completed, the fit to measured data will be as shown in opt_ex09_08.png .

Section 9 : idvdlow_all_temp

This section will extract the parameters for the saturation drain current versus drain voltage characteristics versus temperature. The parameters to be optimized are as follows.

  • AT Temperature coefficient for saturation velocity
  • LAT AT variation for short devices
  • WAT AT variation for narrow devices
  • PAT AT variation for short and narrow devices

After this step has been completed, the fit to measured data will be as shown in opt_ex09_09.png .

The sequence may be run multiple times in order to improve the fit of the model to the measured data as necessary. When complete, the model card can then be exported into an external model library file as shown in the output file opt_ex09.lib.

Additional Info:
Files
opt_ex09.lib
opt_ex09.uds
Graphics
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