Methods and devices for holding a mirror for use in X-ray optical systems
AssigneeNikon Corporation
InventorMasayuki Shiraishi
Life of this patent
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Abstract
Methods and devices are disclose for use in holding mirrors as used in any of various X-ray optical systems. In this context, “X-ray” encompasses the so-called “soft X-ray” or “EUV” wavelengths. The X-ray optical systems can be used, for example, in EUV microlithography systems. A fluid cavity (e.g., an elastic toroidal ring) extends around the circumference of an X-ray mirror. The cavity defines a lumen that is filled with a fluid. The fluid can be static or flowing, and can be a gas or liquid. Holding members are disposed evenly spaced around the circumference of the cavity. Thus, any stress imparted to the mirror by holding is distributed evenly around the circumference of the mirror.
Claims43
A method for holding an optical element in an optical system, comprising:
- providing a fluid chamber containing a fluid and extending peripherally around the optical element;
- and
- mounting the optical element to a holding member such that the fluid chamber is situated between the optical element and the holding member.
5 The method of claim 4, wherein the step of defining the fluid chamber comprises:
- defining a groove extending into the peripheral edge of the optical element;
- extending a ring circumferentially around the peripheral edge of the optical element, the ring having a width sufficient to cover the groove;
- and
- sealing the ring to the groove.
A device for holding an optical element in an optical system, comprising:
- a fluid chamber extending peripherally around the optical element;
- and
- a fluid situated in the fluid chamber;
- wherein the optical element is mounted to a holding member of the optical system such that the fluid chamber is situated between the optical element and the holding member.
An optical element mounted to a holding member, comprising:
- a fluid chamber situated between the optical element and the holding member;
- and
- a fluid situated in the fluid chamber.
A microlithography system, comprising:
- a beam source that generates a lithographic energy beam;
- an illumination-optical system situated downstream of the beam source and configured to guide the energy beam from the beam source to a pattern-defining reticle, the illumination-optical system comprising at least one respective optical element and a holding member for the optical element;
- a projection-optical system situated downstream of the reticle and configured to guide the energy beam from the reticle to a sensitive substrate so as to imprint the pattern on the sensitive substrate, the projection-optical system comprising at least one respective optical element and a holding member for the optical element;
- and
- a chamber containing at least the illumination-optical system and projection-optical system;
- wherein (i) the illumination-optical system further comprises a fluid chamber situated between the respective holding member and the respective optical element, (ii) the projection-optical system further comprises a fluid chamber situated between the respective holding member and the respective optical element, and (iii) a fluid is situated in each of the fluid chambers.
Dependencies are inferred from the claim text.