Was the ghost touch happening on an Apple original, non-repaired iPad digitizer or did it start occurring after a repair?
Low cost digitizers suffer from ghost touching, even with tape applied so this could explain your issue if the screen was ever replaced in the pats. If the digitizer is original, then tape shouldn't be necessary and it is possible that the panel is simply just defective.
Now if this device was ever repaired, dropped or came into contact with water, then there could be other issues but I'll wait for your feedback on that.