Interactive Tools Continue to Stay Miles Ahead .......

Two strengths of any TCAD tool set are the ability to easily setup and run simulations and the ability to effectively analyze the results produced. Silvaco has always placed a high importance on ease-of-use, powerful analysis tools, and the integration of simulators. A focus on better analysis and GUI tools serves to provide users with more insight into the physics of the simulators.

Many enhancements were made to the already powerful Interactive Tools to keep pace with the development of the core simulators. For example, TonyPlot supports the output of <311> cluster concentration, dislocation loop concentration and PROBE statement outputs from ATLAS. The list below concentrates on the major new features of the interactive tools.

Figure 1. DeckBuild control menus for remote execution.

Advanced Run-time control in DeckBuild

• Allow remote execution of jobs. DeckBuild can run on one machine, but the simulator can be run on another machine as long as certain network and permission requirements are met. The local and remote machines may be of different hardware type or operating systems
• Allow simulations to stop on warning message from simulators
• Allow simulations to stop on user-defined strings in the run-time output
• Access to UNIX commands in the input files through the keyword SYSTEM

In some computing environments it is convenient to execute DeckBuild on one machine but have the simulator run on another. A remote execution feature has been added to DeckBuild to allow this. In particular this can be used with supercomputers connected to workstations (eg. Convex with HP J-series workstations). As long as certain network and permission requirements are met jobs can be run on any remote machine supported by Silvaco.

In previous versions simulations under DeckBuild would stop on errors generated by the simulators. However many users requested to stop on warning messages too since in the early stage of simulations these might be important. A switch has been introduced for this. In addition users can now enter particular strings that will cause the simulations to stop. When the string is seen in the run-time output of the simulator the simulation will stop with an appropriate message. Many users also requested the ability to run UNIX commands within the input files. Using the SYSTEM option in DeckBuild this is now possible. Any Unix command can be placed at any point into any input file. This might be used to remove temporary files, copy results to a separate directory or list the current time.

Improved Parameter Extraction

• 2D integration of any solution quantity in a user defined box
• Slope gradients at a user-defined point on a curve
• Extraction of curves of dy/dx versus x from any curve. This can be used recursively to get higher derivatives
• Extraction of elapsed time
• Extraction of lines of maximum or minimum potential. This is typically used in CCD simulations to determine the path of the carriers during charge transfer. The resulting trace can be overlayed on the 2D device structure in TonyPlot
• Support for new quantities produced by ATLAS and ATHENA including the output of MixedMode and the new PROBE statement in ATLAS
• Extraction from SmartSpice results supported

The parameter extraction features of deckbuild are a very important part of the Silvaco user interface. These capabilities have been enhanced to include 2D integration of quantities, calculation of slopes and higher order derivatives and MixedMode quantities. In CCD device simulations there is a specific requirement to plot the line of minimum or maximum potential across the channel region under several gates. A feature to do this has been developed in EXTRACT. The file produced can be overlayed on the 2D mesh as well as be plotted as potential versus x location as shown in Figure 2.

Popup Menus For New Syntax

As expected the menu system in DeckBuild is updated to keep track with the latest developments in the core tools. Some of the new menu items in this release are:

• ATHENA adaptive meshing
• New diffusion models in ATHENA (See Figure 3)
• Addition of Indium as an impurity to process menus
• CURVETRACE command in ATLAS

New Graphics Features

• Speedup in TonyPlot and TonyPlot3D contouring and hardcopy printing
• Ability to export 2D sections from TonyPlot3D to TonyPlot
• Allow deletion of individual structure or log files from overlay plots
• Ability to plot the difference in quantities between two plots on the same mesh
• Transparent minimum contour for TonyPlot
• User-defined charge of animated flow

Figure 4. 2D cross-sections from 3D simulations
can now be saved from TonyPlot3D to TonyPlot.

Many new features have been implemented in TonyPlot and TonyPlot3D based on user feedback. There is now an interface from 2D cross-sections taken from 3D simulation results to TonyPlot. In TonyPlot it is now possible to delete individual plots from a plot overlay. This is particularly useful when plotting LOG files from ATLAS during the simulation. It allows users to follow the progress of the simulation graphically without cluttering the plot with a high number of lines.

Support for Cylindrical and Circular Devices

• Features to define 3D cylindrical structures for advanced MOS processes or power device structures. This allows mixed cylindrical and rectangular structures to be simulated in Device3D.
• Ability to define circular doping sources

One device engineering approach for next generation technologies is to use vertical MOS structures.[1] In terms of simulation these require a mixing of traditional prismatic based 3D device simulation with cylindrical geometries. For Device3D there has never been any problem to simulate such devices. However defining such a complex device structure was very difficult in earlier versions of DevEdit3D. New features to allow circular regions and circular doping sources in DevEdit3D allow users to create stacked MOS structure such as in Figure 5. The IV characteristics of these devices can be determined by Device3D.

Figure 5. Vertical MOS structure created by DevEdit3D.
Device analysis can be performed by Device3D.

Reference

[1] Hanafi et al: IEDM 95 p657