Plotting UTMOST Results Using TonyPlot

Introduction

It is possible to export measured and/or simulated device characteristics from UTMOST to a format that can be used directly by TonyPlot. TonyPlot is Silvaco's general purpose graphical post processing tool used by Silvaco's TCAD software such as ATHENA, ATLAS, and the Virtual Wafer Fab (VWF). TonyPlot's graphical and post processing capabilities are more extensive than UTMOST's internal graphical utility and in some cases this extra functionality is required. This article will describe how measured and modeled data can be exported from UTMOST and visualized using TonyPlot.

 

Example of Data Transfer from UTMOST to TonyPlot

UTMOST was used to extract BSIM3 parameters from NMOS devices from a 0.5µm CMOS process. Measured data from devices with drawn W/L dimensions of 20/10, 20/2, 20/0.8, 20/0.6, 20/0.5, 4/10, 2/10, 1/10, and 0.9/10 µm was collected by UTMOST for the devices in question. The UTMOST BSIM3 extraction routine was then used to extract scalable NMOS and BSIM3 models. In this case no use was made of the UTMOST global or local optimization options to refine or improve the quality of the model parameter sets which were extracted. In some cases such parameter refinement or tuning is necessary. The accuracy of the extracted NMOS model was adequate for the purpose of this example. Figure 1 shows plots of measured and modeled characteristics for one of the device geometries used in this experiment in the case of the NMOS analyses. This device had a drawn width of 20µm and a drawn length of 0.8µm. The simulated device currents and conductances in all measured regions of device operation are in good agreement with the measured data.

 

Figure 1. Measured (oooo) and simulated (____) UTMOST device characteristic
plots for the 20/0.8mm NMOS device where the BSIM3 model was used.

 

 

In order to export data from UTMOST in a format suitable for TonyPlot the batch-mode UTMOST executable was used. The batch-mode command file was constructed and executed from VYPER. The contents of the command file are shown in Figure 2. These batch-mode UTMOST commands could also have been created and run from DeckBuild. DeckBuild is Silvaco's interactive, graphical runtime environment for developing process, device, and batch-mode UTMOST input decks.

 

Figure 2. Batch-mode UTMOST commands to extract
BSIM3 parameters and create data files for TonyPlot.

 

 

The batch-mode commands perform the following main tasks:

Select the MOSFET technology

  • Load an UTMOST setup file
  • Load an UTMOST data Log file (NMOS example shown)
  • Select devices for the BSIM3 extraction
  • Perform a BSIM3 extraction
  • Select device no.3 (20/0.8µm device) for IDS-V GS routine
  • Create TonyPlot measured and simulated IDS-V GS data files
  • Select device no.3 (20/0.8µm device) for the IDS-V DS routine
  • Create TonyPlot measured and simulated IDS-V DS data files;

The batch-mode UTMOST commands shown in Figure 3 create four data files which can be imported into TonyPlot. The demo_idvg_m.log and demo_idvg_s.log files contain measured and simulated IDS-VGS data while the demo_idvd_m.log and demo_idvd_s.log files contain measured and simulated IDS-VDS data. Figure 3 shows some TonyPlot plots created with the NMOS data created by UTMOST. Use was made of the TonyPlot Overlay facility to merge the measured and simulated curves into a single plot. The Duplicate facility was used so that the device currents could be viewed on both linear and log scales. The Function facility was used to create and plot the current derivatives.

 

Figure 3. Measured (xxxx) and simulated (uuuu) TonyPlot device characteristic
plots for the 20/0.8mm NMOS device where the BSIM3 model was used.

 

 

Conclusions

This article describes an example where measured and simulated device UTMOST characteristics are imported into TonyPlot for further analysis. Use was made of the batch-mode UTMOST option in order to create the data files that can be read by TonyPlot. TonyPlot contains many flexible data analysis and post processing options which the UTMOST user may find useful.