pinging @Tim Edwards since you seem to be the efabless analog expert

@Andrew Elliott: Since you said I'm the "analog expert" I'm assuming this is an analog design on caravan. I think I may have a clue here. "Clear area density" is the inverse (1 - x) of "metal area density". Low clear area density means you have way too much metal. But, a week ago we discovered a problem in which somebody had used fill block over their design, and I found out that the klayout DRC deck for density checks was counting the fill block purpose as part of metal area, which of course is completely wrong. But, in that case the clear area density was just below the limit. With the numbers reported above, I have a feeling that you have covered your entire project area with fill block (this might explain the negative numbers, if klayout adds the areas of shapes without subtracting shared area, then fill block over metal shapes might add to over 100%, resulting in a negative clear area). If this is what's going on, then: (1) You are using too much fill block, and you will need to need to restrict fill block to areas which you believe are especially sensitive to fill, so as to get close to the clear area limit. Otherwise, SkyWater will reject the design (and consequently the whole tapeout), so it's not something we can waive. (2) If your fill block is causing clear area errors in precheck but your total metal area (neglecting the klayout DRC deck area) really does fall within the minimum/maximum limits, then we can manually pass your design through precheck if necessary (we are doing that for the other design we learned was failing precheck due to use of fill block). We now have a policy of freezing software versions for a tapeout, meaning that we will manually work around the error for this tapeout, and have the error fixed by the next tapeout.