MAGIC Magic Mailing List
 
 
From: Philippe Pouliquen (philippe AT alpha DOT ece.jhu.edu)
Date: Mon Feb 10 2003 - 13:23:52 EST

  • Next message: Jeff Sondeen: "Re: magic DRC error" 

    > At first, I thought that the root problem was that it is meaningless to
> supply a corner extension distance that is larger than the original
> distance of the error checking.

No, the thing that is 'unusual' about this rule, is that the cornerTypes
is exactly equal to the types1 (both brown in this case).

So the vertical edge between brown (types1) and space (types2) doesn't
necessarily end at the junction between brown and green, because of the
fracturing of the space tiles.

> I would call this a definite error on magic's part.

Nope. (read on)

> Not only is it an error, it's an error in ALL 3 cases, because the
> middle layout only shows the error to 1 unit, whereas the error area
> should be a 2x2 box, reaching all the way to the maximum corner
> extension distance.

There should be NO errors in the layout, because the corner extension
should (normally) not be performed -- the corner material up and to the
right of the brown->space edge is: green!  And green is not in the list of
cornerTypes.

> This should not be dependent on the configuration of space tiles.

The problem is in the way I used the edge rule.  What I was trying to
check for is:  when green abuts brown, make sure that green doesn't make
any 'turns' until it is at least two lambdas away (and vice-versa).  I
shouldn't have used a cornerDist of 4 -- it was unnecessary, just a
leftover from a previous implementation attempt.  Now I'm using something
like the following to avoid spurious error generation:

edge4way green ~(brown,green)/plane 2 ~(brown)/plane green 1 "Error"
edge4way brown ~(green,brown)/plane 2 ~(green)/plane brown 1 "Error"

This is the type of rule needed to ensure that the auto-generated select
masks around diffusion/ohmic don't overlap.  Jeff handles it differently,
but I'm trying to make the rules behave similarly in Magic, Cadence and
L-Edit (so that I don't confuse the poor poor Freshmen and Sophomores that
are taking my Intro to VLSI class).

Philippe Pouliquen
The Johns Hopkins University

    •  
     
    Questions? Contact Rajit Manohar     		cornell logo