Are chicken pox scars created from scratching?

Not necessarily: Chicken pox scars can develop no matter how careful you are about scratching.

Usually: Chicken pox causes pustules which itch intensely. The pustule damages the skin but the scratching makes it really worse. That's why your mother (and your dermatologist) told you not to pick at things on your skin! if you can protect the pustule from scratching damage, it usually heals with a minimal scar unless it gets infected with bacteria.