Klayout 25d View Access
The KLayout 2.5D View is an advanced visualization feature that extrudes 2D layout polygons into a pseudo-3D space. Introduced in version 0.28, it allows designers to inspect vertical relationships in a process stack, such as via alignments and metal layer overlaps, without the complexity of a full 3D CAD environment. Core Concept: Why "2.5D"?
While it looks 3D, the view is technically "two and a half dimensional" because it represents layers as vertically extruded solids with a fixed thickness. It does not model complex process topologies like step coverage or planarization effects, but rather focuses on the relative vertical dimensions of the material stack. Key Features and Capabilities
Vertical Visualization: Ideal for spotting "via stacks" or identifying missing connections between metal levels that are difficult to see in a flat 2D view.
Net Tracing Integration: Users can export a net from the KLayout Net Tracer and view it in 2.5D, making it easier to follow a signal as it moves up and down through the stack.
OpenGL Powered: The feature uses OpenGL for real-time rotation and scaling.
Practical Limits: The current implementation handles approximately 100,000 polygons before performance significantly degrades. How to Use the 2.5D Viewer
To use this feature, KLayout must be compiled with OpenGL support. 1. Creating a 2.5D Script
The viewer relies on a script (a variant of a DRC script) to define the material stack. Go to Tools > 2.5d View > New 2.5d Script.
Define layers using the z function. For example, to extrude Layer 1 (thickness 200nm) and Layer 2 (thickness 300nm):
# Start Layer 1 at 100nm elevation with 200nm height z(input(1, 0), zstart: 0.1.um, height: 200.nm) # Add Layer 2 for the next 300nm z(input(2, 0), height: 300.nm) Use code with caution. 2. Navigation Controls
Navigation revolves around moving a camera relative to a pivot point marked by a compass icon. Mouse/Keyboard Input Rotate (Azimuth/Elevation) Right-click and drag Move Pivot (Translate) Middle-click and drag Zoom (Magnify Layout) Ctrl + Mouse Wheel Top-Level View Hold Shift key Practical Applications
Educational Use: It is highly valued for training new designers to understand the physical reality of a GDSII/OASIS file.
DRC/LVS Debugging: When a Layout vs. Schematic (LVS) error indicates a floating net, the 2.5D view can help visually confirm if a via is physically missing between two metal layers.
Interposer Design: Useful for visualizing advanced packaging structures like silicon interposers that connect multiple dies. 5D script for a specific process like Sky130? Colors in the 2.5d View - KLayout Layout Viewer And Editor klayout 25d view
The 2.5d View in KLayout is a feature that creates a pseudo-3D representation of your layout by extruding 2D layers into vertical blocks. It is primarily a visualization tool used to inspect complex multi-layer structures like via stacks. Key Requirements
OpenGL Support: Your version of KLayout must be compiled with OpenGL support to use this feature.
Performance Limits: It is currently optimized for sections of a layout, with a practical limit of roughly 100k polygons.
2.5d Script: To generate the view, you must use a specialized script—a variant of a Design Rule Check (DRC) script—that defines how each layer is extruded and positioned on the z-axis. How to Use the 2.5d View
Create a Script: Navigate to Tools > 2.5d View > New 2.5d Script to open a template in the macro editor.
Define Extrusions: Use the following functions in your script: z(layer, options): Extrudes a specific DRC layer.
zz(options) block : Groups multiple z statements into a single material for easier display management.
Run the View: Click the Run button in the macro editor or select your script from the Tools > 2.5d View menu. Adjust the Scene:
Z-Scaling: Use the right slider in the 2.5d window to exaggerate the vertical (z) axis, making flat profiles easier to see.
Colors/Visibility: The 2.5d view inherits colors and visibility settings directly from your active Layout View. Navigation Controls Action Rotate (Azimuth/Elevation) Drag with Right Mouse Button Move Pivot (X/Y/Z) Drag with Middle Mouse Button Pivot Forward/Backward Mouse Wheel Zoom Layout Ctrl + Mouse Wheel Snap to Top View Hold Shift Key
For more advanced needs like tapered etch profiles or rounding, users often look to external tools like xView or the integrated xsection tool, as the native 2.5d feature only supports straight vertical extrusions. Colors in the 2.5d View - KLayout Layout Viewer And Editor
In KLayout, the is a visualization feature that transforms flat 2D layout patterns into a semi-3D representation by "extruding" layers vertically. This is particularly useful for visualizing wiring congestion, checking the relative vertical dimensions of a process stack, or inspecting complex via connections in a more intuitive spatial context. Key Features and Requirements Extrusion Mechanism
: Unlike a "true" 3D engine, this tool uses a script to define the material stack, assigning specific thicknesses and starting heights to 2D polygon layers. OpenGL Support The KLayout 2
: The 2.5D view is only available if your version of KLayout was compiled with OpenGL support. Performance Limits
: It is optimized for sections of a layout rather than entire chips; practical performance typically limits viewing to around 100,000 polygons How to Use the 2.5D View
To generate a 2.5D visualization, you must use a specialized script based on the KLayout DRC (Design Rule Check) language Create a Script : Navigate to Tools > 2.5d View > New 2.5d Script Define the Stack function to extrude layers. z(input(1, 0), zstart: 0.1.um, height: 200.nm)
extrudes layer 1/0 starting at a 100nm elevation with a 200nm thickness. Run the View
: Execute the script via the macro editor's "Run" button or from the Tools > 2.5d View Navigation Right-Click + Drag : Rotate (change azimuth and elevation). Middle-Click + Drag : Move the pivot point. Mouse Wheel : Zoom in and out. Visualization and Appearance Layer Linking
: The 2.5D view inherits colors and visibility from the main layout view. If you hide a layer in the 2D window, it disappears in the 2.5D window. Fill Styles
: Changing the fill color or pattern in the layer list will update the "face" color of the extruded blocks in real-time. Pivot Point
: A compass icon on the ground plane indicates the center of rotation and scaling. For detailed API documentation, refer to the D25View Class Reference on the official KLayout website sample script
for a specific process stack (like a standard CMOS metal stack) to get started? Colors in the 2.5d View - KLayout Layout Viewer And Editor
Conclusion
KLayout's 25D viewing capabilities offer a powerful way to visualize and analyze 2D layout data with a third dimension. By mastering its features and leveraging the community and scripting capabilities, users can significantly enhance their workflow and insights into semiconductor designs. Always refer to the most recent documentation and community forums for the latest features and best practices.
The 2.5D view in KLayout is a semi-3D visualization tool that extrudes 2D layout polygons into vertical layers with defined thicknesses. To use it, you must run a script—often a variant of a DRC script—to define the material stack and z-levels. The Architect of Silicon
The clock on the wall hit 3:00 AM, but Elias didn't look up. On his screen, the flat, neon-green polygons of a high-speed modulator were just... flat. In the 2D world, everything was a puzzle of intersections, a maze of GDSII layers that felt more like a blueprint than a machine.
"Let’s see if the vertical coupling actually works," he muttered. He opened the Macro Editor and pulled up his .d25 script. He had spent the last hour meticulously defining the z_start and height for each layer, transforming abstract data into a physical stack. He clicked Run. When to use 2
The 2.5D View window flickered to life. Suddenly, the flat modulator wasn't just lines anymore. The silicon photonics layer rose from the floor of the screen like a translucent crystal city. Above it, the metal vias climbed like skyscrapers, reaching toward the passivation layer.
He used the mouse to tilt the camera. In the 2.5D View, he could see the "extrusion"—the thickness he’d assigned to the cladding. It wasn't "true" 3D—he couldn't see the internal grain of the atoms—but for a chip designer, it was the closest thing to holding the silicon in his hands.
"There it is," he whispered. A small overlap between the waveguide and the metal heater that looked fine in 2D was clearly a collision in the 2.5D world. The metal was sitting too low, threatening to short the optical signal.
With a few keystrokes, he adjusted the script, refreshed the view, and watched the metal layer lift safely into place. The "2.5D Architect" had saved the tape-out once again. Colors in the 2.5d View - KLayout Layout Viewer And Editor
allows you to visualize 2D layouts as extruded 3D objects, providing a clearer perspective on layer stacks and connectivity. Accessing the 2.5D View Open your layout in the KLayout Editor Navigate to the to open the visualization in a new tab. Navigation Controls The view uses camera-based movement relative to a pivot point (marked by a compass icon): Rotate (Azimuth/Elevation) Right-click + Drag Move Pivot (Up/Down/Left/Right) Middle-click + Drag Move Pivot (Forward/Backward) Mouse Wheel Zoom (Magnify/Shrink) + Mouse Wheel Top-Level View Toggle Keyboard Panning Arrow Keys Keyboard Rotation + Arrow Keys Key Features
: The 2.5D view automatically extrudes the 2D shapes based on layer definitions. Net Tracing Integration
: You can export specific nets from the Net Tracer and visualize them in 2.5D to inspect complex routing, such as a VDD net. Visibility
: Like the standard 2D view, you can adjust layer visibility and order to focus on specific parts of the stack. Tips for Better Visualization Database Units
: Ensure your database units are set correctly in the initial layout setup, as this affects the scale of objects. Layer Properties : You can adjust layer textures and colors in the Layer Toolbox
to make different materials more distinguishable in the 2.5D rendering. Performance : If the layout is extremely complex, use the Cell Hierarchy
to show only specific cells as "top" to improve rendering speed. for the 2.5D extrusion or how to export these views as images? Colors in the 2.5d View - KLayout Layout Viewer And Editor
When to use 2.5D vs full 3D
- Use 2.5D for rapid visual checks, documentation, and stackup discussions.
- Move to full 3D CAD/FEM when accurate 3D geometry, slope modeling, or material-based physical simulation is required.
2. "Flying" Polygons
Because the height is assigned by layer, if a polygon exists on a layer, it is extruded to that height globally. If a designer manually draws a shape that should be on a different vertical plane (e.g., a metal jump), the 25D view will render it incorrectly unless it is moved to a different GDS layer number. The visualization is data-dependent, not context-aware.