KLayout includes a native 3D rendering engine (utilizing OpenGL).
This is where most 2.5D viewers fail, but KLayout shines due to its efficient database engine. However, if you are working with a full-chip GDS (10GB+), rendering millions of extruded polygons will lag.
Optimization Checklist:
You might ask: Why not just export to OpenAccess or GDSII and load into a real 3D tool like FreeCAD, Blender, or Cadence Virtuoso 3D?
The answer is iteration speed. Full 3D exports involve lossy conversions, axis rescaling, and meshing of millions of polygons, which can take hours. The 25D view in KLayout works live on the current layout database. You can: klayout 25d view
This real-time feedback is invaluable for detecting errors like unwanted layer overlaps, missing vias, or unintended metal cantilevers in MEMS.
| Tool | 25D Feature | Cost | Best For | |------|-------------|------|-----------| | KLayout | Extrusion-based, OpenGL, live update | Free (GPL) | Quick visual checks, MEMS, small-to-medium ICs | | Cadence Virtuoso 3D | True 3D with material properties | $$$ Commercial | Advanced node full-custom IC | | Magic VLSI | Wireframe 3D, no shading | Free | Academic, very old hardware | | OpenROAD | No native 25D; requires external renderer | Free | RTL-to-GDS flows | | Klive (KLayout extension) | Experimental voxel-based 3D | Free | Research-grade volumetric analysis | KLayout includes a native 3D rendering engine (utilizing
KLayout’s advantage is simplicity – you do not leave the tool. No export, no conversion, no separate window management (beyond one extra view).
In 2.5D and 3D stacked ICs, TSVs are vertical interconnects passing through the silicon. Their shape is circular in 2D, but in 25D view, you can assign a substantial height (e.g., 100 µm) and see how TSVs from different tiers align. In practice, designers use the 25D view to check that landing pads fully encircle via bottoms. This is where most 2
When training new layout engineers, it is difficult to explain that a "Contact" is a hole in the oxide, not a physical block. In 2.5D, you can set the "Implant" layer to height 1, "Oxide" to height 10 (transparent), and "Contact" to height 11. The student literally sees the contact piercing the oxide.