I have been designing photomasks with AutoCad for some time.  I believe you
can either use either wide polylines or closed polylines of zero width.  I
have never used wide polylines, as I don't feel comfortable with their
etherial quality - you can't snap to an edge.
I use closed zero-width polylines.

 You shouldn't have any problem if you keep a couple of simple rules in
mind:

1.  The regions must be bounded by single closed polylines.  If you need to
create a region with multiple boundries , you must create it from a
superposition of single bounded regions.  For example to create a donut (2
boundries) draw half the donut (1 boundry) then mirror to create the whole
as the sum of 2 halves.

2.  The mainstream semiconductor industry does not know the meaning of a
circle or arc - the masks consist only of line segments.  If you need a
circle use a polygon with a sufficiently large number of sides.

3.  The polylines usually can have a maximum of ~2000 line segments.  If you
need more, break the region down into smaller regions'

-----Original Message-----
From: Christi Guthrie 
To: [email protected] 
Date: Wednesday, January 12, 2000 11:12 AM
Subject: How do you make a mask file in autocad?


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>hello,
>
>i need to make a fairly simple mask, and i would like to use autocad =
>since i know it fairly well...
>
>i have found a good, fairly affordable (linkedit) dxf -> cif,gds =
>converter, but my question is this: do u draw a closed polyline (ie a =
>rectangle) or a pline w/ some nonzero width (ie 5 units =3D 5um). if i =
>draw rectangles, the resulting cif file is composed of polygon (P) =
>commands followed by vertices. if i draw wide lines, the resulting cif =
>file is composed of wire (W) commands.
>
>is one better than the other...or does it really matter? or do you do =
>something completely different.
>
>any tips appreciated,
>
>dan
>
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hello,
>
 
>
i need to make a fairly simple mask, and i would =
>like to use=20
>autocad since i know it fairly well...
>
 
>
i have found a good, fairly affordable (linkedit) =
>dxf ->=20
>cif,gds converter, but my question is this: do u draw a closed polyline
>=
>(ie a=20
>rectangle) or a pline w/ some nonzero width (ie 5 units =3D 5um). if i =
>draw=20
>rectangles, the resulting cif file is composed of polygon (P) commands =
>followed=20
>by vertices. if i draw wide lines, the resulting cif file is composed of
>=
>wire=20
>(W) commands.
>
 
>
is one better than the other...or does it really =
>matter? or do=20
>you do something completely different.
>
 
>
any tips appreciated,
>
 
>
dan
>
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>