I know many people use pre-mixed CF4/O2 gas for PECVD clean (CF4 10%?)
I am curious that how can the gases stay mixed in the bottle? Most likely
they have diffrent densities, and one will float, the other will sink.
I noticed my cleanning program plasma color is less bright (indicating
less CF4 content), and need longer cleaning time. Could it be O2 is
floated upward in the bottle?