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From: Philippe Pouliquen (philippe AT alpha DOT ece.jhu.edu) Date: Tue Mar 25 2003 - 13:34:10 EST
On Mon, 24 Mar 2003, Jeff Sondeen wrote: > > edge m2 space/metal2 4 space/metal2 space/metal2 3 \ > > "Metal 2 spacing must be at least 4" > > edge m2 space/metal2 3 space/metal2 space/metal2 4 \ > > "Metal 2 spacing must be at least 4" > > this is marvelous, but i'm not sure it would work. i think magic will > throw away the 4-lambda spacing of the first line when it sees the > 3-lambda spacing of the second line (and likewise with the diagonals). Yes, I was concerned about that too, and since it had been over a year since I had last tried it, I tested it again with the attached tech file. It seems to work fine, but I didn't go any further with it for the same reason that Tim didn't make Euclidean distances the default: I'm not convinced that its safe. When feature sizes get small enough so that the mask features are near the wavelength of the light used for photolithography, the mask creators apparently do some "funny" things to the mask to get sharper corners and/or avoid interference effects. I don't know any details about this, but it does make me wary about using Euclidean distances (yes, I'm paranoid). E-beam lithography doesn't have this problem, but I don't want to create an SCMOS layout that works fine with E-beam but not reticle stepping. If MOSIS would come out and say officially that all design rule distances are Euclidean, then I'd be happy... Philippe
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