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 measure the OvDistance (overlapping distance) of layout objects.

1. Preliminary steps

To run this example, open a Guardian DRC session and choose
File->Open
to load the project
“drc_ex10.eld”
. Then open the top cell
drc_ex10
using the
Cell->Open…
menu.

2. OvDistance command for error detection

Some DRC rules require an overlap measurement of two different layers. For example, for a given device it may be necessary
to have the NWELL layer going under the gate area by a minimum of 30nm. This type of rule can be implement using the
OvDistance
command.

OvDistance
is used to measure the admissible distance between the inner surfaces of sides of regions from the first input layer,
and the inner surfaces of sides of regions from the second input layer.

The syntax for this rule is:

   OvDistance: Layer1= < input layer identifier1 >,
               Layer2= < input layer identifier2 >,
               Value= < value >, Type= < check type >,
               LayerR1= < result layer identifier1 >,
               LayerR2= < result layer identifier2 >,
               Options = (list of check options),
               ID = < error identifier >;

in which:

• Layer1
  is the first layer name being measured
• Layer2
  is the second layer name being measured
• Value
  is the value in um of the measurement
• Type
  can be greater than, less than, (>, <, ==, !=, …)
• LayerR1
  is the layer name in which the geometries of layer1 in violation of the rule would be saved
• LayerR2
  is the layer name in which the geometries of layer2 in violation of the rule would be saved
• Options
  is the list of additional option to the check
• ID
  is the error message that would be display and listed in the log when the error occur

Figure 1
illustrates the syntax that can be used to implement such a task.

A detailed description of all options that can be used for the different rules can be found in the
Guardian DRC user manual
section
2.3.9.1: Common Syntax: Parameters and Options.
Section 2.3.9.7 describes the OvDistance command. The user manual
“guardian_users1.pdf”
can be found in
lib/expert/4.14.0.R/docs/
in your installation area.

It is to be noted that some options are not allowed for certain DRC checks. For the “OvDistance” operation, the options: D, U, IS, N, N’ (
Acute adjacency, Obtuse adjacency, Self intersecting, Notch,
and
Notch Only
) are not allowed.

3. Experimenting with the OvDistance 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_ovdistance_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 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.

Guardian DRC can also be launched 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 desired DRC script. The rest of the steps are identical to the Guardian DRC flow.

Output Results

Input Files

drc_ovdistance_01.dsf

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

// Layers mapping definition section
Layers:
  act		( 43, 0	/* mapped */)
, po1           ( 46, 0	/* mapped */)
;

Merge_input: on;

// derived internal layer over the whole layout cell
Substrate: options=(nosize), LayerR=⊂  

// derived internal layer opposite of ACTIVE layer
Logicform: &not_active=&sub.DIF.act; 


// Minimum poly gate extension passed active.
OvDistance: Layer1=po1, Layer2=&not_active, Limits<1.0 ,
 ID="Min POLY gate extension 1um";




// END of DRC check