process emulation

[simbilod]

Instead of specifying geometries "as fabricated", it should be doable to "emulate" process fabrication. This is not as good as physical process simulation, but can be appealing.

• substrate
  • GMSH box
  • size defines process domain in x, y, z
• masked conformal growth/deposition of thickness t
  • create a new entity by occ.fuse all existing entities
  • masking: occ.cut vertically across the domain where the mask covers the substrate
  • apply occ.dilate on the entity by the desired thickness (isotropically a=b=c=t or directionally e.g. a=b=0, c=t; other types of growth at other angles also possible)
  • if isotropic, occ.fillet the dilated entity's curves by radii = t; this will maintain a distance of t from the previous surface everywhere
  • occ.cut by the original occ.fuse: this also allows tagging of the new grown layer
• masked etching
  • full overetch hack: occ.cut the tag of a grown layer by an infinitely tall box (or other shape if isotropic or non-vertical anisotropy) with x-y dimensions matching mask opening
  • otherwise can occ.cut with a grown gas layer (complement of current fuse with process domain) where exposed
• alternate depositions and etches as needed
• cleanup
  • occ.cut outside the process domain in x,y