mask rule check

**MRC** (Mask Rule Check) is the **verification that OPC/ILT-corrected mask patterns are physically manufacturable by the mask shop** — checking that mask features satisfy minimum feature size, minimum spacing, maximum jog angle, and other constraints imposed by the mask writing and inspection tools. **MRC Rules** - **Minimum Feature Size**: Mask features must be large enough for the mask writer to resolve — typically >40-60nm on mask (4× reduction = >10-15nm on wafer). - **Minimum Space**: Minimum gap between mask features — constrained by mask etch resolution. - **Maximum Jog Width**: The width of jogs (steps in edge position) must be large enough to be written reliably. - **Corner Rounding**: Sharp corners are rounded during mask writing — MRC defines minimum radius. **Why It Matters** - **Manufacturability**: OPC/ILT can create features that look great in simulation but cannot be fabricated on the mask. - **Feedback Loop**: MRC violations require OPC/ILT re-run with tighter constraints — iterate until MRC-clean. - **Cost/Yield**: MRC violations that reach the mask cause mask defects — expensive rework ($100K-$500K per mask). **MRC** is **can the mask shop actually make this?** — verifying that OPC-corrected designs are physically manufacturable within mask fabrication constraints.