Advanced CAD System for Electromagnetic MEMS Interactive Analysis

(CIF file for canonical_3d.ccpds);
DS 1 1 1;
L GND;
B 60 500 0 0;
L DIMP;
B 100 10 0 0;
L MORE;
B 100 360 0 0;
L CPZ;
B 40 150 0 -90;
B 40 150 0 90;
L TOP;
B 30 500 0 0;
DF;
C 1;
E
Figure 3-7: CIF file for canonical test device.
3.3.3 Example of extending Geodesic – Reactive ion etching
In the current implementation of the CCPDS inside of Geodesic, etching is performed by
extruding the mask and subtracting the resulting solid from the layers specified by the
“EtchRemoves” option. While this emulates some physical processes well, on non-planar
geometry it can be a poor approximation. Fig. 3-8 shows a schematic of reactive ion etching.
The yellow region on the left represents the material that should be removed by an idealized
reactive ion etch of unit depth. The figure on the right shows what occurs using the “vfab”
scripts inside of Geodesic to perform the etch. In this case the yellow region represents material
which should have been removed but was not.
One of the examples included with the beta release of Geodesic has an example script
implementing an idealized reactive-ion etch. The key points of this example are now
summarized. We assume we have three given objects:
1. 3-D solid model of a layer named “etchMe” we wish to etch by a unit depth.
2. 2-D polygonal solid of an etch mask named “myMask”.
3. 3-D solid named “mems_device” which is the exterior of the entire device.
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