I have solved this problem myself:
When it says M1 W filler density > 50% -- solution is to reduce the area of M1 layer.
when it says M1 W filler density < 25% -- solution is to increase the area of M1 layer.
Thanks for following up Kok Gnee.
I was interested in this myself and considered replying but I guess I didn't understand if you were getting false errors, or real errors and I hoped someone else would have better ideas than I did.
One thing I am still wondering about is whether this kind of density check is practical for such a small cell. I've seen how density checks are important for a completed design, and also for large blocks, but I still wonder if density checks are practical for tiny cells.
If you (or anybody else) have an opinion please let me know.
Thanks for your reply!
Initially, I didn't understand the meaning of it. Only until recently that I manage to find out the reason and solve it. That might be due to insufficient study and research in this area.
Regarding your questions: I'm also wondering why there is such a need for such a tiny cell?!