A chemical-mechanical planarization device and a method for using a chemical-mechanical planarization device in conjunction with a semiconductor substrate is provided. In accordance with some embodiments, the device includes: a pad disposed over a rotatable platen; a carrier head disposed over the pad and configured to retain a semiconductor substrate between the pad and the carrier head; a tank configured to retain a liquid containing composition; at least one tube fluidly coupled with the tank, the at least one tube comprising a photocatalyst therein; a nozzle fluidly coupled with the tank through the at least one tube and configured to supply the liquid containing composition onto the pad; and a light source configured to provide light to irradiate the photocatalyst, and the liquid containing composition passing through the at least one tube.