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# Subtraction Between two layers?

Last post Wed, Dec 12 2012 2:21 PM by murtazaak. 2 replies.
 Started by murtazaak 11 Dec 2012 08:27 AM. Topic has 2 replies and 666 views
• #### Tue, Dec 11 2012 8:27 AM

• murtazaak
• Joined on Tue, Dec 11 2012
• Posts 4
• Points 50
Subtraction Between two layers?
 Hi, I just started cadence couple of days back for designing my patterns, I wanted to subtract two layers and already wrote a code but not sure its a right one or not. Could anyone help me please and let me know is this a right on or not, load("/usr/cdscad/libw/utils/rectw.il")procedure( subtraction( @optional origin ww tlength outlayer)(prog (xx yy np xo yo lw)   subl1 = nil   subl2 = nil   xo = xCoord(origin)   yo = yCoord(origin)   ;; Draw First rect Layer   xx = xo   yy = yo-ww/2.0   r = rectw(xx yy tlength ww "metal1") subl1 = append(subl1, list(r));; Draw Second rect Layer   xx = xo   yy = yo-ww/2.0   r = rectw(xx yy tlength ww "metal2")  subl2 = append(subl2, list(r))dbLayerAndNot((getEditRep) outlayer subl1 subl2))) Thanks
• Post Points: 20
• #### Tue, Dec 11 2012 8:58 PM

• kb how
• Joined on Fri, May 6 2011
• Melaka, Melaka
• Posts 79
• Points 1,075
Re: Subtraction Between two layers?
 hi Mustazaak,Not sure what you're trying to do. Maybe you can give a brief description to let us understand your intension.Else, just use function dbLayerAndNot is help. -How-
• Post Points: 20
• #### Wed, Dec 12 2012 2:21 PM

• murtazaak
• Joined on Tue, Dec 11 2012
• Posts 4
• Points 50
Re: Subtraction Between two layers?
 Hi Melaka,First of all thanks for your reply, I think you are right that I didn't clearify the things in detail. I am designing the program first in Cadence. For that I am using icfb for compiling, gedit as a editor for writing my code and output of program can see in Virtuoso. Now as I mentioned the code in my previous post, actually I am creating two metal(polygon) layers on exactly same location (both layers x-axis and y-axis are same). Let suppose Layer1 and Layer2 has two layers on same location, obviously when my output come on Virtuoso I can see only one Layer but Layer1 and Layer2 should be behind it which I can't see because of same location. Now what I want is that I can subtract from Layer1 to Layer2 or vise versa so that when my output come on Vituoso it shows only Layer1 not Layer2. Actually I am desiging first my patterns in Cadence then I have to use E-line(lithography) on Silicon chip to write these patters. I am facing the problem that temporary my layer1 is subtract to other layer2 otherwise on E-line it write both layers that make the chip worse.Hope I explained in detail if not so then please ask again, Cheers
• Post Points: 5