Tips and Tricks

Here it finally is - Tips and Tricks - one of my favorite subjects. These will have a heavy Silvaco bias, as that is what I am currently using.

See comments on the parallel Atlas page. (12/18/98).

I am adding a new TMA-specific Tips page, courtesy of Carl Huster. Your contributions are welcome. (Nov 2, 1998).

  • PISCES allows you to regrid on several parameters, typically doping. Actually, early manuals probably went overboard with the doping regridding. It's more important to regrid the channel and the depletion layers than the actual junction location (well, at least for MOSFETs). Turns out that you can regrid on an arbitrary box if you simply omit the regrid criteria (e.g. DOPING, POTENTIAL). You usually need to specify SMOOTH=1 to get well formed triangles, but there are cases where you are better off without it. (7/98)

  • My favorite undocumented TCAD trick is the "!" in SUPREM4, which allows you to execute a shell command from within SUPREM4. Scott Irving (National) used this to call S3 in order to do a sheet resistance extraction in S4. My typical application is to remove files to make sure they aren't there. In S4, you can save the structure at every time step during an oxidation. This can be useful for very slow oxidations, such as a stress-dependent LOCOS simulation. Also useful if the program crashes during an oxidation. "dump=1" saves after every time step; the default prefix for the saved structures is "s", and the rest of the file name will be the elapsed time, e.g., s000000.002. Before you execute this, you might want to remove the structures from previous runs: ! remove s000*
    diffus time=100 temp=900 wet dump=1

    Turns out that SILVACO has extended this capability to other programs within Deckbuild/VWF with SYSTEM. This is not well documented, but I find it highly useful. (5/12/98).

  • I used to close PISCES log files by opening up new dummy log files. Atlas allows "log off" to close a file. But beware of a recent discovery of mine: while running deckbuild on a Sun, and remotely executing Atlas on an HP, an extract failed because the extract started before the log file was closed. (4/21/98).

  • Silvaco has lots of very nice example files that you can load and run in deckbuild. Tip: just load the file, and rather than running it, jump to the tonyplot statements and simply execute them. Loading the examples also loads the results! (4/21/98).

  • It's possible to do "physical" extracts in Atlas, as long as you first save the structure, and then specify the structure file. By default, Atlas loads the last log file. Now, once you know that, you can extract the inversion layer thickness, which is handy for comparing to your grid spacing. Here is an example:
    	output     flowlines
    	save       outf=lin.sol         -- no quotes here
    	extract init inf="lin.sol"      -- quotes here
    	extract name="i50" x.val from curve(depth,impurity="Current Flow"  \
    		material="Silicon" mat.occno=1 x.val=0) where y.val=0.5
    	extract name="i90" x.val from curve(depth,impurity="Current Flow"  \
    		material="Silicon" mat.occno=1 x.val=0) where y.val=0.1
    	extract name="i99" x.val from curve(depth,impurity="Current Flow"  \
    		material="Silicon" mat.occno=1 x.val=0) where y.val=0.01

    The above extracts the depth where 50, 90 and finally 99% of the current flows. The extraction is done at x=0, which was the center of the channel in my example (4/21/98).

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    This page last updated Dec 18, 1998 by