A method includes providing a photomask having a patterned absorption layer over a substrate. The photomask is irradiated with a beam having a mixture of transverse electronic (TE) waves and transverse magnetic (TM) waves. The irradiating includes generating surface plasmonic polaritons (SPP) on a sidewall of the patterned absorption layer. The SPP is used to suppress the TM waves while reflecting the TE waves. A target substrate is exposed to TE waves.

A reflector comprising a hollow body having an interior surface defining a passage through the hollow body, the interior surface having at least one optical surface part configured to reflect radiation and a supporter surface part, wherein the optical surface part has a predetermined optical power and the supporter surface part does not have the predetermined optical power. The reflector is made by providing an axially symmetric mandrel; shaping a part of the circumferential surface of the mandrel to form at least one inverse optical surface part that is not rotationally symmetric about the axis of the mandrel; forming a reflector body around the mandrel; and releasing the reflector body from the mandrel whereby the reflector body has an optical surface defined by the inverse optical surface part and a supporter surface part defined by the rest of the outer surface of the mandrel.

An optical assembly includes: an optical element, which is transmissive or reflective to radiation at a used wavelength and has an optically used region; and a thermally conductive component, which is arranged outside the optically used region of the optical element. The thermally conductive component can include a material having a thermal conductivity of more than 500 W m.sup.−1 K.sup.−1. Additionally or alternatively, the product of the thickness of the thermally conductive component in millimeters and the thermal conductivity of the material of the thermally conductive component is at least 1 W mm m.sup.−1 K.sup.−1.

Extreme ultraviolet (EUV) mask blanks, methods for their manufacture and production systems therefor are disclosed. The EUV mask blanks comprise a substrate; a multilayer stack of reflective layers on the substrate; a capping layer on the multilayer stack of reflecting layers; and an absorber layer on the capping layer, the absorber layer made from amorphous tantalum nitride formed by non-reactive sputtering.

Provided are an optical device capable of effectively preventing contamination and a method for preventing contamination of the same. An optical device according to an embodiment includes a light source that generates light containing EUV (Extreme UltraViolet) light or VUV (Vacuum UltraViolet) light, a chamber in which an object to be irradiated with the light is placed, an optical element placed inside the chamber to guide the light, an introduction unit that introduces hydrogen or helium into the chamber, a power supply that applies a negative voltage to the optical element in the chamber, an ammeter that measures an ion current flowing through the optical element, and a control unit that adjusts the amount of the hydrogen or the helium introduced according to a measurement result of the ammeter.

A multilayer film structure, and method of making such a multilayer film structure, which includes a first layer consisting essentially of a first material and a second layer consisting essentially of a second material. In embodiments, the multilayer film structure includes a plurality of first layers alternating with a plurality of second layers. The layers are constructed by applying a N.sub.2-based reactive sputtering methodology so that the layers maintain a largely amorphous microstructure and a stable and high reflectivity upon annealing at temperatures up to 800° C. for 1 hour.

An optical element (1) includes: a substrate (2); applied to the substrate (2), a multilayer system (3) which reflects EUV radiation (4); and also applied to the multilayer system (3), a protective layer system (5) which comprises a first layer (5a), a second layer (5b) and a third, in particular topmost layer (5c), where the first layer (5a) is disposed closer to the multilayer system (3) than the second layer (5b), and where the second layer (5b) is disposed closer to the multilayer system (3) than the third layer (5c). The second layer (5b) and the third layer (5c) and also preferably the first layer (5a) each have a thickness (d.sub.2, d.sub.3, d.sub.1) of between 0.5 nm and 5.0 nm. A related EUV lithography system having at least one such optical element is also described.

An extreme ultraviolet light condensation mirror includes a substrate, and a multi-layer reflective film provided on the substrate, formed by alternately stacking an amorphous silicon layer and a layer having a refractive index different from a refractive index of the amorphous silicon layer, and configured to reflect extreme ultraviolet light, a layer on a most surface side in the multi-layer reflective film being the amorphous silicon layer containing a silicon atom bonded with a cyano radical.

Provided are an optical device capable of effectively preventing contamination and a method for preventing contamination of the same. An optical device according to an embodiment includes a light source that generates light containing EUV (Extreme UltraViolet) light or VUV (Vacuum UltraViolet) light, a chamber in which an object to be irradiated with the light is placed, an optical element placed inside the chamber to guide the light, an introduction unit that introduces hydrogen or helium into the chamber, a power supply that applies a negative voltage to the optical element in the chamber, an ammeter that measures an ion current flowing through the optical element, and a control unit that adjusts the amount of the hydrogen or the helium introduced according to a measurement result of the ammeter.

Embodiments disclosed herein include methods of patterning a back end of line (BEOL) stack and the resulting structures. In an embodiment a method of patterning a BEOL stack comprises forming a grating over an interlayer dielectric (ILD), and forming a spacer over the grating. In an embodiment, the spacer is etch selective to the grating. In an embodiment, the method further comprises disposing a hardmask over the grating and the spacer, and patterning the hardmask to form an opening in the hardmask. In an embodiment, the method further comprises filling the opening with a plug, removing the hardmask, and etching the spacer. In an embodiment, a portion of the spacer is protected from the etch by the plug. In an embodiment, the method may further comprise removing the plug, and transferring the grating into the ILD with an etching process.