Hints, Tips and Solutions

Volume 12, Number 6, June 2002

Q: (From “Hints and Tips” of Simulation Standard Vol. 10, No.9, 1999) How can I cut exacly the same hole in many layers?

A: In recent versions of Expert a special option is added to do exactly this operation. In addition to “Normal”, “Merge”, and “Hole” options of object creation, option “Edit>>Region Mode>>Hole Selected” allows you to make a hole or cut of any shape in all selected shape objects at the same time. (The corresponding button is added to the Drawing Bar as well.)


Q: How to skip a single layer during stream-out?

A: There is a common way to control the output of layers during stream-out. This is performed using layer remapping tables, or layer maps. A layer map is a file of simple format: each line contains three parameters: Expert’s layer name, the required GDSII number and the required DATATYPE. A layer map is assigned using the Setup>>GDSII I/O>>Output panel. Only layers listed in the layer map a streamed out. So’ if you want to skip a single layer, you must prepare a layer map that contains all your design layers but one.

The easiest way to make one is as follows.

(1) At the layer Bar, make all layers visible

(2) Make the one you want to skip, hidden.

(3) Run the “View>>Layer View>>Layer Lists>>Save Visible Layer List” command.

This command will prompt you to select a file name with extension *.ELL. This file will be the required layer map.


Q: I found something very strange on OutDistance checking. Please see the attached file, the distance of P2 to Ntub is 2um, but OutDistance checking will treat it as LT 2um.

My script is

OutDistance: Options=(O), 

Layer1=&P2, Layer2=&hvnNtub,
Type=LT, Value=2um,

A: From the image I see that the distance is checked between 45-degree segments. If your geometry is on grid, it is impossible for the distance between such segments to be exactly 2um. It could be, e.g., 1.99998082. Under default Expert layout editor settings, this value will be shown as 2.0. You may see the value, if you increase the “numeric display resolution” by increasing the “Decimals displayed” value in the Setup>>Editor/Viewer>>Viewing panel.

Therefore, if you have non-90 geometry to check, you must use “Tolerance” parameter set, e.g., to 0.001um. WARNING: that if your geometry is purely orthogonal, the tolerance is unused, for faster calculations. Therefore if you want ensure that some distance is within, e.g., 0.299 and 0.3001, please use the “Range” distance parameter of the DRC check, rather than set the tolerance.


Q: When distance between two objects is less than minimum gap, the filler box is created if its sizes are more than minimum width for this layer. (Compass, Synthesis, p. 16) How can we do this in Expert?

A: You may try the DRC command with option “R”, e.g.,

Distance: Options=(O,L1=GT 1um,R), Layer=Contact,              
Type=LE, Value=2um;

The “R” option is to write error trapezoids into the LayerR layer.


Call for Questions

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Phone: (408) 567-1000 Fax: (408) 496-6080
email: support@silvaco.com