Abstract: A reticle includes a border section surrounding a pattern section, and gas openings arranged in and passing through the border section. The gas openings are coupled to a gas supply. Each gas opening extends in a first direction inclined to and forming an angle with a reticle center axis that extends perpendicularly away from a front surface of the reticle, and is configured to blow a pressurized gas in the first direction away from the front surface to create an air wall adjacent to and surrounding the front surface, thereby advantageously preventing particles from falling on the front surface of the reticle.

Abstract: A method includes: protecting a mask of a mask assembly by a frame thereon during translating the mask assembly to a position associated with a region of a substrate, the frame having height less than a focal plane associated with a selected particle size; directing extreme ultraviolet (EUV) radiation toward the mask; reflecting radiation carrying a pattern of the mask toward the mask layer; forming a feature of a semiconductor device in a layer underlying the mask layer according to the pattern.

Abstract: A method includes: determining whether a first pellicle is to be inspected for inner particles; and in response to the first pellicle being to be inspected: forming a mask layer on a substrate; forming a defocused light path by shifting a mask assembly; exposing the mask layer by defocused light having a focal plane separated from the first pellicle by a distance; taking an image of the substrate; determining whether a threshold value is exceeded by analyzing the image; in response to the threshold value being exceeded, replacing the first pellicle with a second pellicle; and in response to the threshold value not being exceeded, processing production wafers using the first pellicle.

Abstract: A reticle includes a border section surrounding a pattern section, and gas openings arranged in and passing through the border section. The gas openings are coupled to a gas supply. Each gas opening extends in a first direction inclined to and forming an angle with a reticle center axis that extends perpendicularly away from a front surface of the reticle, and is configured to blow a pressurized gas in the first direction away from the front surface to create an air wall adjacent to and surrounding the front surface, thereby advantageously preventing particles from falling on the front surface of the reticle.