Introduction: The Limitations of Flat Layouts For decades, integrated circuit (IC) and microelectromechanical systems (MEMS) designers have relied on two-dimensional (2D) tools to create complex physical layouts. KLayout, the open-source, high-performance layout viewer and editor, has become an industry favorite precisely because of its lightning-fast 2D rendering and robust polygon manipulation. However, as semiconductor technology pushes into advanced nodes (5nm, 3nm) and heterogeneous integration (chiplets, TSVs, and MEMS structures), the limitations of flat, top-down viewing become painfully apparent.
It is not a full 3D simulator – and that is perfectly fine. For tape-out checks, MEMS topology inspection, and even client presentations, the 2.5D perspective offers the best trade-off between speed, clarity, and physical insight. With a few minutes of layer height assignment, you can see your design the way it will exist on silicon: as a three-dimensional object, not just a geometric abstraction. klayout 25d view
For extremely large layouts (>10 GB GDSII), create a quick 25D view by first using Hierarchy > Flatten on selected cells, then reduce detail with Edit > Selection > Convert to polygons with a tolerance of 0.01 µm. Comparing KLayout 25D with Other Tools | 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 | Introduction: The Limitations of Flat Layouts For decades,
# Example KLayout Ruby script to export a 25D view as PNG view = RBA::Application::instance.main_window.current_view view.set_config("use-2.5d", "true") # Set layer heights programmatically layer_index = view.layer_index_for(LayoutView::Layer.new(1, 0)) view.set_layer_property(layer_index, "2d-height", 0.5) # Capture image image = RBA::Image::new(view.max_viewport_width, view.max_viewport_height) view.render_image(image) image.save("layout_25d_snapshot.png") This allows batch processing of multiple layout versions, each with a standardized 45° tilt and lighting setup – perfect for regression visual diff testing. The KLayout roadmap includes discussions about true 3D rendering using ray marching or voxel cones. However, the maintainers (notably Matthias Koefferlein) have been cautious due to performance concerns. Most users agree: the current 25D mode hits a sweet spot. It is not a full 3D simulator – and that is perfectly fine
So open KLayout, enable OpenGL, assign a height to your metal3 layer, and tilt that view. Your next layout bug – or your next elegant solution – will reveal itself in the third dimension. About the author: This article is written for IC, MEMS, and PCB layout professionals using KLayout. For further reading, consult the official KLayout documentation under “2.5D View” and explore the user forum threads on setting realistic layer heights for your specific technology node.