Minimum Required Version
: Expert 4.14.0.R, Guardian 4.14.0.R

This example will demonstrate how the Guardian DRC tool can be used to resize layout objects, or more specifically, undersize them.

1. Preliminary steps

To run this example, open a Guardian DRC session and choose
File->Open
to load the project
“drc_ex17.eld”
. Then open the top cell
drc_ex17
using the
Cell->Open…
menu.

2. Undersize command description

This command creates a new layer by resizing the regions of the input layer. When a region is undersized, its edges are shifted inside the
region by a specified distance, while remaining parallel to their initial orientations.

This command is mostly used in combination with other commands to perform a more complex Design Rule Check.
For example, we could undersize an implant layer (PIMP) by X um and see if the ACTIVE layer that is supposed to be completely enclosed by PIMP,
still is. If any of the ACTIVE layer is not covered by the undersized version of PIMP, then the enclosure was not appropriate.

Guardian DRC
provides an
InDistance
check, which would most likely be used in this case, but the point here is to illustrate that the command
Undersized
is often combined with other logic to detect a more complex rule violation.

The syntax for this rule is:

   Undersize: Value = < value >,
              Layer = < input  layer identifier >,
              LayerR= < output layer identifier >;

in which:

• Layer
  is the layer name being undersized
• Value
  is the distance in um of the undersized operation
• LayerR
  is the layer name in which the reduced geometries of layer would be saved

Figure 1
illustrates a rule deck that utilizes the undersized command.

The user manual
“guardian_users1.pdf”
can be found in
lib/expert/4.14.0.R/docs/
of your installation area. Section 2.3.9.8 describes the Undersize command.

3. Experimenting with the Undersize command

Once all the example files have been downloaded and the preliminary steps described in 1.0 are completed,
complete the following steps:

• Choose
  Verification->DRC->DRC Script panel
  . In this new window, choose
  File->Open…
  and select
  “drc_undersize_01.dsf”.
  
• Press
  DRC->Run
  
• To inspect the errors, choose
  Verification->DRC->Errors->Load errors…
  you should get a window as shown in
  Figure 2.
• Select the check and press the
  Load
  button located at the bottom of the window. Then choose
  Verification->DRC->Errors->First error
  to display the error in the layout, as shown in
  Figure 3
  .
• To unload the error choose
  Verification->DRC->Errors->Unload errors
  .

Note that these two
toolbars
can be used to access the DRC menu command. To turn the visibility of the toolbar ON and OFF, choose
View->Toolbars
and select
DRC
and
DRC error inspection.

It is to be noted that Guardian DRC can also be launch from within the layout editor tool Expert. Within an Expert
session follow the steps described in 1.0 to open the eld file. Then choose
Verification->DRC->DRC Script panel.
In this new window, choose
File->Open…
and select the desired DRC script. The rest of the steps are identical to the Guardian DRC flow.

Output Results

Input Files

drc_undersize_01.dsf

//****************************************************************//
//           Example DRC rule for UNDERSIZE check operation      //
//****************************************************************//

// Layers mapping definition section
Layers:
  cnt		( 25, 0	/* mapped */)
, act		( 43, 0	/* mapped */)
, pps		( 44, 0	/* mapped */)
, nps		( 45, 0	/* mapped */)
, po1           ( 46, 0	/* mapped */)
, m1            ( 49, 0	/* mapped */)
, vi1           ( 50, 0	/* mapped */)
, m2            ( 51, 0	/* mapped */)
;

Merge_input: on;


//Rules for SELECT layers
//4.2  Minimum select overlap of active
Logicform: &sel=pps.or.nps;

// the line below creates a reduce version of the combined SELECT layers
UNDERSIZE: Layer=&sel, value=1um, LayerR=&sml_sel;

Logicform: &error = act.dif.&sml_sel;
Copy: Layer=&error, ID="Enclosure of ACTIVE by SELECT <1um";

// END of DRC check