How is ozone produced in the stratosphere?

UV-C and more energetic radiation from the Sun shatters oxygen molecules. Excess kinetic energy in the oxygen atoms is dissipated against various molecules, until finally individual oxygen atoms find a temporary home on either nitrogen or argon, in a very unstable relationship, not really a molecule. Then sometimes another oxygen atom comes by, and the extra oxygen atom is transferred to it make ozone. Most times it is another unstable molecule holding another oxygen atom and molecular oxygen is reformed instead.