Clipping to a Round Boundary
The Hextract program is ideal for clipping a large array to a round boundary.
a) it allows the user to define a round boundary with as much "smoothness" as needed.
b) it only explodes the cells that actually cross the boundary -- the great majority are left intact.
c) it gives the user several options on what to do with geometries that cross the boundary: clip them, retain them in their entirety or drop them.
d) it enables the user to specify which layers to process.
Because we want to generate separate GDSII files for each mask, we'll use HEXtract in command line mode where we can set up the parameters for each of the 5 layers.
HEXtract Command Line Syntax
We'll create a simple batch file that calls HEXtract 5 times -- once for each layer. You can see it below along with some annotation. (the real command line has no breaks but we've introduced them merely for readability.) We are assuming all input and output files are in our "current" directory.
c:\wcad\hextract\hxtractor32.exe <- launches the hextract program array_all.gds <- the multi-layer arrayed data rdl_after_clip.gds <- the output file -layers:2 <- only process layer 2 (our RDL) -roundwindow:0,0,97500,12,2 <- round window centered at 0,0 w radius = 97500 <- the last two parameters control the smoothness
We'll repeat the same command line changing the layer each time and the output file name. The only difference will be on the solder mask layer. For that layer we will use the additional option -drop_partial_poly.
hextractor32.exe array_all.gds via1_after_clip.gds -layers:1 -roundwindow:0,0,97500,12,2 hextractor32.exe array_all.gds rdl_after_clip.gds -layers:2 -roundwindow:0,0,97500,12,2 hextractor32.exe array_all.gds via2_after_clip.gds -layers:3 -roundwindow:0,0,97500,12,2 hextractor32.exe array_all.gds ubm_after_clip.gds -layers:4 -roundwindow:0,0,97500,12,2 hextractor32.exe array_all.gds solder_after_clip.gds -layers:5 -roundwindow:0,0,97500,12,2
Here is what the RDL layer looks like after a round clip by HEXtract.
full view of wafer ...
zoomed in ...
zoomed in again ...
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