This is caused by the low amount of sunlight in Anartica during its winter, since sunlight causes oxygen to ionize into ozone.
This has nothing to do with CFC's or Freon, but a lot to do with sunlight.
You are incorrect on this subject. The "ozone hole" refers to drastically lowered ozone concentrations in the Antarctic stratosphere above the winter polar vortex, due to the reactions of chlorine with ozone that are catalytically enhanced on ice crystals in polar clouds.
If you would really like to "get science", I recommend this outstanding Web site on the subject:
The Ozone Hole Tour. Part 3, "The Science of the Ozone Hole", will be of particular interest to you.
Now there is a very strong correlation between volvanic avtivity and ozone thinning in the respective hemisphere, particularly if the valvanoes in question are very active and generate a lot of chlorine. Measurable ozone thinning in the north did occurr, for example, after the very large Mt Pinatubo eruption. It just happens that the most active volcanoe in the world is Mt Erabus in, you guessed it, Antarctica. It's been more or less continuously erupting for decades.
I wish I could remember his name.