Klayout 25d: View [work]

The 2.5D View in KLayout is a powerful visualization tool that extrudes 2D layout layers into a 3D-like perspective. It is primarily used to inspect material stacks and vertical layer relationships, which can be difficult to visualize in a standard flat view. Core Requirements & Setup

OpenGL Support: The 2.5D view is only available if your KLayout version was compiled with OpenGL support.

2.5D Scripting: To use the tool, you must create a script that defines how the layers are stacked and extruded. These scripts use a variant of the DRC (Design Rule Check) language.

Performance: The practical performance limit is currently around 100,000 polygons. How to Use the 2.5D View

Create a New Script: Go to Tools > 2.5d View > New 2.5d Script. This opens a new script template in the macro editor.

Define Extrusions: Use specific DRC functions to build your stack: z(layer, [options]): Extrudes a specific layer.

zz([options]) block : Groups multiple z statements to create complex 3D material geometries.

Run the View: Click the Run button in the macro editor or select your script from the Tools > 2.5d View menu.

Sync with Layout: The 2.5D window displays the section currently visible in your main layout view. If you close the window, you can reopen it via Tools > 2.5d View > Open Window. Navigation & Controls

Rotation: Drag with the right mouse button to change the viewing angle (azimuth and elevation).

Movement: Drag with the middle mouse button to pan the view or use the arrow keys.

Zooming: Use the mouse wheel to move the camera forward/backward, or Ctrl + Mouse Wheel to magnify the layout.

Exaggerate Height: Use the Z-axis zoom slider (on the right) to exaggerate height variations, which is helpful if the real height profile is too flat to see clearly. Visual Customization

Colors & Visibility: The 2.5D view inherits colors directly from your active KLayout Layer Properties. If you hide a layer or change its fill color in the main window, the 2.5D view updates accordingly. klayout 25d view

Net Tracing: While primarily for geometry, it is possible to export a specific net (e.g., from the Net Tracer) to visualize its path through different vertical layers. Colors in the 2.5d View - KLayout Layout Viewer And Editor

allows you to visualize a 2D layout in 3D by extruding layers vertically based on a script

. This is particularly useful for verifying material stacks, such as MEMS devices or CMOS metal layers. 1. Prerequisites OpenGL Support

: KLayout must be compiled with OpenGL support for the 2.5D viewer to work. Performance Limits

: It is optimized for small to medium designs; a practical limit is roughly 100,000 polygons Layout Setup : Ensure you are in Editor Mode if you need to create or modify layers first. 2. Getting Started

To generate a 2.5D view, you need a script that defines the material stack using a specialized version of the KLayout DRC language Navigate to New 2.5d Script This opens the Macro Editor with a template script. Define your layer stack using the functions. 3. Scripting Basics The script tells

how high each layer should be extruded and at what starting point in the Z-axis z(layer, options) : Extrudes a specific layer. : The elevation where the extrusion begins. : The thickness of the material. zz(options) block : Combines multiple

statements into a single display group for complex material geometries. Example Script:

# Extrude Layer 1/0 starting at Z=0.1um with a thickness of 200nm ), zstart: .um, height: # Extrude Layer 2/0 for 300nm on top of previous layers ), height: Use code with caution. Copied to clipboard 4. Running the View : Click the button in the Macro Editor or select your script from the Window Management

: Once run, the 2.5D window will pop up. If closed, re-open it via Open Window Visibility Follows Selection

: You can enable this option in the viewer settings to only show the 3D extrusion of parts you have selected in the 2D layout. 5. Troubleshooting Script not showing in menu

: Check if the script is configured to be "bound to a menu item" in the Macro Development environment Window is blank : Ensure your

values are not zero and that you have valid shapes on the specified input layers. complex script example involving multiple material groups or specific 3D navigation shortcuts? The 2.5d View - KLayout Layout Viewer And Editor The 2

7. Conclusion

The KLayout 2.5D View is a highly effective, cost-efficient solution for physical design verification. It moves the designer beyond the abstraction of GDSII layers into a representation of physical reality.

For general layout engineers, the Cross-Section View is the most valuable tool for verifying process geometry. The 3D Viewer serves as an excellent communication tool for design reviews and packaging verification. While it does not replace process simulation tools, it is an indispensable part of the open-source IC design ecosystem.

Recommendation: Users are advised to maintain accurate layer mapping files (.lyp or tech files) that include thickness data to maximize the utility of this feature.

Unlocking the KLayout 2.5D View: A Comprehensive Guide KLayout's 2.5D View is a specialized visualization tool that transforms flat 2D mask layouts into semi-3D representations through vertical extrusion. Introduced in version 0.28, this feature allows designers to inspect the vertical stack of a semiconductor process, helping to visualize wiring congestion and relative material heights. What is 2.5D View?

Unlike a true 3D viewer that might support arbitrary angles and curved surfaces, the 2.5D view in KLayout works strictly by taking 2D polygon layers and extruding them vertically. It cannot model complex process topologies (like conformal coverage) but excels at showing how different metal, poly, and diffusion layers sit on top of each other. Key Technical Requirements

OpenGL Support: The 2.5D view is only available if your KLayout build was compiled with OpenGL support.

Performance Limits: Currently, the tool has a practical limit of approximately 100,000 polygons. Setting Up Your First 2.5D Scene

To use this tool, you must provide a script that defines the "material stack"—essentially telling KLayout which layers to extrude and to what height.

Create a New Script: Navigate to Tools > 2.5d View > New 2.5d Script. This opens the macro editor with a template based on the Design Rule Check (DRC) language.

Define Extrusions: Use the z function to define layer heights.

z(layer, zstart: 0.0, height: 1.0): This extrudes a specific layer from a base (zstart) to a certain thickness (height).

zz ... : This combines multiple z statements into a single display group for easier material management.

Run the Script: Click the "Run" button in the macro IDE. A new 2.5D window will appear, rendering the section of the layout currently visible in your main viewer. Navigation and Controls Perspective Navigation You can rotate

The 2.5D window uses a camera-based navigation system relative to a pivot point marked by a compass icon. Rotate (Azimuth/Elevation) Drag with Right Mouse Button Move Pivot (Up/Down/Left/Right) Drag with Middle Mouse Button Move Pivot (Forward/Backward) Mouse Wheel Zoom (Magnify/Shrink) Ctrl + Mouse Wheel Top-Down View Toggle Press and Hold Shift Scaling the Z-Axis

Because semiconductor layers are often very thin relative to their width, the 2.5D view includes a Z-axis zoom slider on the right side of the window. Increasing this factor exaggerates the vertical dimensions, making it easier to see height variations that would otherwise appear flat. Advanced Visualization Features

Layer Syncing: The 2.5D view respects your 2D layout settings. If you change a layer's fill color or hide it in the main viewer, it will update in the 2.5D window.

Material Visibility: A dedicated list on the right allows you to toggle specific material groups on or off, which is useful for "peeling back" upper metal layers to see lower-level transistor structures.

Net Highlighting: By exporting a net from the Net Tracer, you can visualize a specific electrical path as it moves vertically through vias and different metal layers. Colors in the 2.5d View - KLayout Layout Viewer And Editor

1. MEMS and NEMS Design

MEMS devices (accelerometers, gyroscopes, micromirrors) rely heavily on third-dimension geometry: suspended beams, comb drives, and proof masses. A 2D top view cannot reveal if a movable structure will collide with an underlying substrate. Using KLayout’s 25D view:

• Assign height to structural polysilicon and sacrificial layers.
• Tilt the view to inspect undercut clearance.
• Spot potential stiction zones where tall structures bend too close to the substrate.

3. Antenna Rule Violation Intuition

Antenna effect violations occur when long metal traces collect charge during plasma etching, potentially damaging thin gate oxides. While DRC (Design Rule Check) tools flag ratios, the 25D view provides a visual intuitive check: long, high-extruded metal fingers floating over a low-lying poly gate become dramatically visible. You can literally see the "antenna" sticking up.

Step 3: Launch the 25D Window

Navigate to View > New 2.5D View. A separate window opens, initially showing your layout as a flat, extruded landscape. Use the mouse:

• Left-click + drag – Rotate view (azimuth and elevation).
• Right-click + drag – Pan.
• Scroll wheel – Zoom.
• Shift + left-click – Reset view to default.

3. Rendering Artifacts

In very dense designs with overlapping transparent layers, Z-fighting (flickering textures when two surfaces occupy the same plane) can occur. This is a common OpenGL artifact but can be distracting when trying to inspect fine details.

Seeing Depth in a Flat World: The Power of KLayout’s 2.5D View

In the world of semiconductor design, layout visualization is traditionally two-dimensional. Integrated circuit (IC) layouts are composed of flat polygons on distinct layers representing masks for doping, polysilicon, metal routing, and vias. However, as modern chips stack multiple metal layers and complex interconnects, the need to perceive relative depth without full 3D rendering has grown. KLayout, a popular open-source EDA tool, addresses this need with its "2.5D View" (often called the 3D preview or 25D view). This feature bridges the gap between flat schematics and true 3D models, offering designers an oblique perspective that simulates depth, layer stacking, and vertical separation. This essay explores the purpose, functionality, practical applications, and limitations of KLayout’s 2.5D view, demonstrating why it is an indispensable tool for modern physical verification and layout analysis.

Key Features of KLayout’s 2.5D Mode

1. Layer Extrusion Height
   Each layer can be assigned an arbitrary height in the Z-dimension. By default, layers are extruded uniformly, but advanced users can script relative heights to mimic real dielectric thicknesses.

2. Perspective Navigation
   You can rotate, pan, and tilt the view interactively. This makes it easy to inspect via stacks, overlapping geometries, and potential spacing violations that might be invisible in pure top-down mode.

3. Color & Transparency
   Layer colors from your standard GDS palette are preserved, but transparency can be adjusted. This prevents occlusion when many layers are extruded simultaneously.

4. Real-Time Performance
   Unlike heavyweight 3D CAD tools, KLayout’s 2.5D view uses efficient OpenGL rendering. Even large designs (hundreds of MB) remain responsive.