The inventive concepts relates to a photomask, and more particularly, to a photomask having high durability.
In order to satisfy high performance and low cost desired by users, there has been increasingly requested for forming smaller patterns on a semiconductor substrate. To meet these technical requirements, the wavelength of a light source used in a lithography process has become shorter. For example, in the past, the lithography process utilized light having a g-line wavelength band (e.g., 436 nm) or an i-line wavelength band (e.g., 365 nm). Use of light having a deep-ultraviolet, or extreme ultraviolet (EUV) wavelength band is becoming more common. As light having an EUV wavelength band is mostly absorbed by refractive optical materials, an EUV lithography generally utilizes a reflective optical system instead of a refractive optical system.
USPTO Backgrounds
USPTO Backgrounds