Before an IC chip enters the tape-out phase, engineers must prepare extensively to ensure the smooth progress of subsequent stages, and a reasonable layout design is key to ensuring chip performance, reliability, and cost-effectiveness.
1. Pin Layout Optimization
Clearly define the direction and position of the pins, especially keeping the clock pins and analog signal pins at a proper distance to reduce signal interference.
2. Potential Isolation
Ensure effective separation of n-well regions with different potentials, especially in mixed-signal circuits, to prevent potential crosstalk.
3. Dummy Resistor Application
To improve resistance matching, add dummy resistors and ensure they are grounded at both ends.
4. Layout Symmetry
For circuits with high matching requirements for differential pairs, use structures like finger and dummy to ensure layout symmetry and optimize signal transmission characteristics.
5. Consistency of MOS Gate Orientation
In the same module, unify the orientation of MOS gates to avoid mixing orientations, optimizing routing and signal consistency.
6. Standard Cell Check
Confirm that Tap Cells, Tie High, Tie Low Cells, etc., in digital standard cells are correctly connected to power or ground to avoid logical errors.
7. IO Ring and Filler Filling
Add Pad Fillers on digital and analog IO rings, and Core Fillers in the digital core to optimize layout density and reduce parasitic effects.
8. ESD Protection Layout
Use a dual finger structure to layout ESD protection devices, placing the source on both sides and the drain in the middle to optimize the uniform conduction of ESD current.
9. Wafer Slot Reservation
Reserve sufficient slot spacing (at least 80μm) for multi-target tape-outs, and try to maintain that the chip can be cut through in one go in both horizontal and vertical directions, simplifying the cutting process.
10. MPW Tape-Out Area and Shape
For MPW tape-outs, precisely control the chip area to be slightly smaller than the specified size and ensure the chip shape is rectangular to facilitate the splicing and utilization of MPW layouts.
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