Hints, Tips and Solutions

Q. How can I extract BSIM4 parameters using UTMOST III ?

A. The BSIM4_FI routine in UTMOST III MOS module should be used for data collection and BSIM4 SPICE model parameter extraction. The BSIM4_FI routine features are similar to the BSIM3_MG routine. The BSIM4_FI routine will collect four types of measured data curves from each device:

1) IDS/VGS @ low VDS bias.

2) IDS/VDS @ VBS=0V.

3) IDS/VGS @ High VDS bias.

4) IDS/VDS @ High VBS bias.

After the data collection is completed the menu item "Measure&extract" in the Fit Variables screen should be set to "1". This will enable the automatic parameter extraction and refinement process. (Figure 1.)

Figure 1. BSIM4_FI routine "Fitting Variables" screen.


If the "Measure&extract" flag is set to "1" the extraction will start after the measurement is completed or after loading the log file and pressing the "Measure" button will start the extraction. The BSIM4_FI routine is very easy to use and the routine will extract and refine BSIM4 parameters with user inputting only few process related parameters (TOX, XJ, NCH) in to the fit and opt columns of the parameters screen. The extracted parameters will be copied into the parameters screen.

The BSIM4_FI routine is an automatic parameter extraction and refinement routine. The simulation and local/Global optimization should be performed using the ALL_DC routines. The measured data collected with BSIM4_FI routine can be shared by any ALL_DC routine.

After the parameter extraction is completed the quality of the fits should be examined by running the SPICE simulation against the measured data in ALL_DC routine. The further fine tuning of the parameters can be achieved by using the Local optimization strategies. The local optimization strategies between Satrtegy#51 and Strategy#60 are developed by Silvaco specifically for the BSIM4 model parameter optimization. (Figure 2.)

Figure 2. Local Optimization Strategy#51 : idvg_large_bsim4


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