[SOLVED] what is maximum and minimum density check

[preethi19]

hi i learnt minimum density check is done to avoid sweeping out during etching on less dense areas.

Could anyone pls tell me wat maximum density check is done. I found in one post

"Maximum density check should be done to avoid the dishing ( i.e the plane surface dipping down due to heavy weight of the metal above it because oxide is porous)..."

My understanding is two metals say metal 1 and metal 2 are separated by oxide layer. So which layer dishes out and how. Can anyone pls explain this.. Thank you!!!