Description

Short wavelength lasers such as a KrF laser and an ArF laser are widely used as lithography light source for exposure of circuit patterns on a photomask onto a wafer surface in response to miniaturization of semiconductor devices. Especially, illumination energy of the ArF laser used for the most advanced devices is high and such illumination sets off chemical reaction of gaseous material in the vicinity of the photomask surface and subsequently generates solid state foreign materials with growth potential, which are called as Haze.