Games / Command flash cards / Sign-off checks and violations / DFM (Design for Manufacturing)

DFM (Design for Manufacturing)

Each card shows a command to explain. A missed card returns later in the round and starts the schedule over. A card answered correctly moves up the schedule and next appears after 1, 3, 7, then 21 days. Keys 1 to 4 choose an option, h shows a hint, and Enter moves on. A hint keeps the card where it is on the schedule. An ordering card is answered by clicking its items in order, and one wrong click ends it. Time values are in nanoseconds. Progress is stored in this browser.

SourceThese cards describe the checks a design must pass before tapeout, using the rule decks that ship with OpenROAD-flow-scripts: the KLayout runsets for sky130 and ASAP7 and the sky130 layout-versus-schematic runset. Rule names and values are quoted from those files. Every process has its own rules; the families and the reasons behind them are what carry across. Reference: the sky130 design rule documentation (the open rule decks on GitHub).
All 3 cards in this section, with answers
  • the area where a particle of a given size would cause a failure
    A yield estimate: how much of the layout is vulnerable to random defects.

    Hint: Two layouts can both be legal and still not yield the same.

    Two wires at minimum spacing over a long run are more likely to be bridged by a particle than the same wires spread apart. The analysis turns layout into a predicted defect rate, and it is why spreading wires and widening them where there is room is worth doing. the open rule decks reference

  • a pattern that passes every rule but does not print correctly
    A shape the process cannot resolve, found by simulating the printing.

    Hint: The rules are a simplification of what the lithography really does.

    Rules are a conservative summary of a physical process, and some combinations slip through. Simulating the optics, or matching the layout against a library of known bad patterns, catches those. The fix is usually a small local change to the routing. the open rule decks reference

  • why a density rule has a minimum as well as a maximum
    Polishing dishes a sparse area and leaves a dense one proud.

    Hint: The wafer is polished flat after each layer.

    The surface has to be flat before the next layer is printed, or that layer is out of focus. Chemical and mechanical polishing removes more where there is less metal to resist it, so the rule forces an even spread. Fill exists to satisfy it. the open rule decks reference