Illumination apparatus
AssigneeNikon Corporation
InventorAkihiro Goto
Life of this patent
Estimating the term…
Abstract
A compact illumination apparatus reduces nonuniformity in the Gaussian intensity distribution of a laser beam and reduces interference noise due to an optical integrator. The illumination apparatus illuminates a mask with a predetermined pattern. A light source supplies a light beam. The light beam is split into multiple beams by multiple reflections between a totally reflective surface and a partially reflective surface. The totally reflective and partially reflective surfaces being inclined with respect to each other. The multiple beams are split to form multiple light source images.
Claims38
An illumination apparatus that illuminates a mask with a predetermined pattern, comprising:
- a light source that supplies a light beam;
- a multi-beam forming optical system that includes a reflecting member and a light splitting member and that converts said light beam into a group of multiple beams;
- said light splitting member and said reflecting member being inclined with respect to each other at some non-zero angle chosen so that a first partial transmitted beam emitted from said light splitting member at a first point and an nth partial transmitted beam emitted from said light splitting member at an nth point are convergent and so that the distance between the first point and the nth point on the light splitting member is shorter as compared to the distance between the first point and the nth point when the light splitting member and the light reflecting member are parallel with respect to each other.
A method of reducing coherency of light comprising:
- a) positioning a reflecting member and a light splitting member wherein the members are inclined at a predetermined angle with respect to each other so that a first partial transmitted beam emitted from said light splitting member at a first point and an nth partial transmitted beam emitted from said light splitting member at an nth point are convergent and so that the distance between the first point and the nth point on the light splitting member is shorter as compared to the distance between the first point and the nth point when the light splitting member and the light reflecting member are parallel with respect to each other.
An illumination apparatus that illuminates a mask with a predetermined pattern, comprising:
- a light source that supplies a light beam;
- a multi-beam forming optical system that includes a reflecting member and a light splitting member and that converts said light beam into a group of multiple beams, said light beam being supplied to said light splitting member and said reflecting member to be at least partially reflected therebetween, said light splitting member and said reflecting member being inclined with respect to each other at a predetermined non-zero angle chosen so that a first partial transmitted beam emitted from said light splitting member and an nth partial transmitted beam emitted from said light splitting member are convergent;
- and
- an optical integrator receiving the plural partial transmitted beams from said multi-beam forming optical system to form multiple image sources therefrom.
An illumination apparatus that illuminates a mask with a predetermined pattern, comprising:
- a light source that supplies a light beam;
- a multi-beam forming optical system that includes a reflecting member and a light splitting member and that converts said light beam into a group of multiple beams, said light splitting member and said reflecting member being inclined with respect to each other at a predetermined non-zero angle chosen so that a first partial transmitted beam emitted from said light splitting member at a first point and an nth partial transmitted beam emitted from said light splitting member at an nth point are convergent and so that at some point along the said reflecting member a reflected light ray will reflect back toward the point on the said light splitting member at which the original incident ray impinged.
Dependencies are inferred from the claim text.