Apparatus is provided for mounting a pellicle to a photomask. A chamber has at least one port for filling the chamber with extreme clean dry air (XCDA) or an inert gas. A pellicle mounter is provided within the chamber. A vacuum ultra violet (VUV) light source is provided for irradiating a mask held by the pellicle mounter while the chamber is filled with the XCDA or inert gas. The mask is irradiated with the VUV light in an atmosphere of the XCDA or inert gas, and the pellicle is mounted to the mask while the mask is in the atmosphere of the XCDA or inert gas and exposed to the VUV light.