Faceted EUV optical element
AssigneeASML Netherlands B.V.
InventorsDavid C. Brandt, Alexander I. Ershov, Igor V. Fomenkov
Life of this patent
Estimating the term…
Abstract
A reflective EUV optic such as a collector mirror configured as an array of facets that are spaced apart to form respective gaps between adjacent facets. The gaps are used as inlets for gas flow across one of the facets such that flow is introduced parallel to the optic surface. The facets can be made with offsets such that loss of reflective area of the EUV optic can be minimized. The gas facilitates removal of target material from the surface of the facets.
Claims20
An EUV light source comprising:
- a reflective EUV optic comprising a first facet comprising a first portion of a reflective surface of the reflective EUV optic and a second facet comprising a second portion of the reflective surface of the reflective EUV optic, the first facet being separated from the second facet by a gap;
- and
- a gas supply in fluid communication with the gap.
An EUV light source comprising:
- a chamber;
- a reflective EUV optic in the chamber, the reflective EUV optic being substantially rotationally symmetric about a central optical axis and comprising a first annular facet comprising a first portion of a reflective surface of the reflective EUV optic and a second annular facet comprising a second portion of the reflective surface of the reflective EUV optic, the first facet being separated from the second facet by an annular inlet, the reflective EUV optic further comprising a plenum in fluid communication with the annular inlet;
- and
- a supply of gas in fluid communication with the plenum and at a pressure higher than a pressure in the chamber.
An EUV light source comprising:
- a chamber;
- a reflective EUV optic in the chamber, the reflective EUV optic being substantially rotationally symmetric about a central optical axis and comprising a plurality of annular facets comprising respective portions of a reflective surface of the reflective EUV optic,
- the plurality of annular facets together making up substantially the entire reflective surface,
- each of the annular facets being spaced away from adjacent annular facets by a respective one of a plurality of annular inlets in a direction parallel to the central optical axis of the reflective EUV optic,
- a supply of gas in fluid communication with the plurality of annular inlets and at a pressure higher than a pressure in the chamber so that gas flows from the supply and into the chamber through the annular inlets,
- each of annular facets overlapping at least one adjacent annular facet in a direction substantially tangential to the reflective surface where the annular facet overlaps the adjacent annular facet to create one of the plurality of annular inlets, the plurality of annular inlets thus being configured to direct the gas from the supply in a direction tangential to the reflective surface where the annular facets overlap.
A method of generating EUV light, the method comprising the steps of:
- providing a reflective EUV optic having a first facet comprising a first portion of a reflective surface of the reflective EUV optic and a second facet comprising a second portion of the reflective surface of the reflective EUV optic, the first facet being separated from the second facet by a gap;
- flowing gas from a gas supply through the gap tangentially past the second portion of the reflective surface of the reflective EUV optic;
- and
- generating a plasma which produces EUV radiation.
Dependencies are inferred from the claim text.