EPFL Swiss Institute of Technology Lausanne
CMi Center of MicroNanoTechnology
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How to thrive with LinkCAD
Version of 2017-07-29. Get the latest one at cmi.epfl.ch/photo/files/design/linkcad.install.pdf
1. Introduction
There are two schools of thought in computer
aided design (CAD) and/or electronic design
automation (EDA) software. One comes from the
semiconductor industry, where closed polygons
define the areas on a photolithography mask
where light passes (or not), which is then pattern
transferred to a wafer for an additive or a
subtractive process. Another comes from the
mechanical engineering world, where on a
drawing/blueprint a polygon or a line defines the
path along which a milling or cutting tool has to
been moved to produce a mechanical part.
When the two worlds converge as they do at CMi,
you have mechanical engineers using their
habitual software formats on the equipment
specified by the MEMS design engineers, and
problems arise: the photolitho mask does not
understand where the light has to pass given that
there is not inside or outside on an non-closed
polyline, and the cutting tool does not understand
what to do with a closed polygon. You also have
MEMS people trying to pass their layout to a
machine that does PCB, which does not know how
to move it’s tool along a path defined as a closed
polygon.
habitual, special format into “GDSII”, which is
the one format which produces the least problems
with the Heidelberg Instruments conversion
software used for MLA150 and VPG200. It does
not mean this is the best format, but it is the one
we observe the least problems with. We have
many users using “CIF” without any problems, but
we have quite some having problems getting all
their shapes exactly out of the “CIF” format, and
we see very rarely people who have problems with
the “GDSII” format.
2. typical: DXF to GDSII
configure the converter
dxf import options
But this is only an issue of format and language,
and this is where the great diplomat, the united
nations safe ground of all formats, linkCAD, enters
the field.
LinkCAD allows to view, convert and transform
layout among data formats. The lists of formats
that it is able to read from, and then the list of
formats that it is able to write to, are impressive,
although not completely orthogonal.
CMi recommends the use of LinkCAD to
transform your layout from your favorite,
gdsii export options
EPFL Swiss Institute of Technology Lausanne
CMi Center of MicroNanoTechnology
Page 2
Change from the “convert” mode to “view”
mode:
Result of reading in the dxf file:
In the view mode, there still are no convex
polygons:
A peek at the dxf layout in klayout shows the
extended lines, and the absences of convex
polygons.
The “show open polylines” button is turned
off:
---
If you click on it, then the “View” forms get
triangles to indicate the error
EPFL Swiss Institute of Technology Lausanne
CMi Center of MicroNanoTechnology
Rite result out:
Toggle back to “convert” mode,
Select the
[ x ] Close open zero-width polylines and
splines.
Inspect ersult also in klayout:
“execute”
Here the result:
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EPFL Swiss Institute of Technology Lausanne
CMi Center of MicroNanoTechnology
;
Convinced?
3. CIF to no-extension CIF
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EPFL Swiss Institute of Technology Lausanne
CMi Center of MicroNanoTechnology
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EPFL Swiss Institute of Technology Lausanne
CMi Center of MicroNanoTechnology
4. LinkCAD Tools
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