In pellicle cleaning, a gas is flowed on a pellicle using at least one gas nozzle. During the flowing, the pellicle is moved respective to the at least one gas nozzle. During the flowing, the pellicle is exposed to ionized gas generated by at least one alpha ionizer. Also during the flowing, an ultrasonic wave is applied to the pellicle using an ultrasound transducer or transducer array. The gas nozzle may have a nozzle aperture comprising a slit or a linear array of apertures arranged parallel with a pellicle membrane of the pellicle.