gdsii format

**GDSII** (Graphic Data System II) is the **standard binary file format for storing IC layout data** — representing the physical design as a hierarchical collection of polygons, paths, and references organized in cells (structures), used for design interchange between EDA tools, foundries, and mask shops. **GDSII Format Details** - **Hierarchy**: Designs are organized as cells (structures) that can reference (instantiate) other cells — compact representation. - **Geometric Elements**: Boundaries (polygons), paths (lines with width), text, and structure references (instances). - **Grid**: All coordinates are on a fixed grid — typically 1nm or 0.5nm database unit. - **Layers/Datatypes**: Features are organized by layer number and datatype — encoding different process layers. **Why It Matters** - **Industry Standard**: GDSII has been the IC industry standard since the 1980s — universally supported. - **Limitations**: 32-bit coordinates, 2GB file size limit, no curved elements — increasingly constraining for advanced nodes. - **Replacement**: OASIS (Open Artwork System Interchange Standard) addresses GDSII's limitations for advanced designs. **GDSII** is **the lingua franca of chip design** — the universal IC layout format that connects design tools, foundries, and mask shops.