Illumination system having a more efficient collector optic
View Patent ↗An illumination system having a light source is disclosed, the light source having a source size and emitting radiant power in a spatial angle element Ω(α), α indicating the aperture angle, a collector, which collects radiant power from the source up to a first maximum aperture angle α max(1) , a first geometric flux G 1 being defined by the source size Q and the first maximum aperture angle α max(1) , a plane to be illuminated having an area A and a numerical aperture NA to be illuminated, the numerical aperture NA to be illuminated defining a second aperture angle α (2) , and a second geometric flux G 2 being defined by the area A and the second aperture angle α (2) , distinguished in that the collector has a first maximum aperture angle α max(1) , which is selected in such a way that the first geometric flux G 1 is equal to or larger than, particular preferably more than 15% larger than the second geometric flux G 2.
1. An illumination system comprising:
a light source that emits radiant power in a spatial angle element Ω(α), wherein α indicates an aperture angle, and wherein said light source has a density distribution having a shape;
a collector that collects said radiant power up to a first maximum aperture angle α max(1) , a first geometric flux G 1 being defined by said shape and said first maximum aperture angle α max(1) ;
a plane to be illuminated having an area A and a numerical aperture NA, wherein said numerical aperture NA defines a second aperture angle α (2) ; and
a second geometric flux G 2 being defined by said area A and said second aperture angle α (2) ,
wherein said first geometric flux G 1 is more than 15% greater than said second geometric flux G 2 .
2. The illumination system according to claim 1 ,
wherein said first geometric flux G 1 is less than 300% of said second geometric flux G 2 .
3. The illumination system according to claim 1 ,
wherein said collector comprises a plurality of rotationally-symmetric mirror shells positioned one inside another around a common axis of rotation.
4. The illumination system according to claim 1 ,
wherein said collector has a central shading and a first minimum aperture angle α min(1) assigned thereto.
5. The illumination system of claim 1 ,
wherein said collector is a normal incidence collector.
6. The illumination system of claim 1 ,
wherein said light source is a discharge plasma source.
7. A projection exposure system comprising:
(a) the illumination system of claim 1 , for illuminating a mask positioned in or near said plane; and
(b) a projection objective for imaging said mask on a light-sensitive object.
8. The illumination system of claim 1 , wherein said first geometric flux G 1 is less than 200% of said second geometric flux G 2 .
9. The illumination system of claim 1 , wherein said first geometric flux G 1 is less than 130% of said second geometric flux G 2 .
10. The illumination system according to claim 1 , wherein said shape has a first dimension and a second dimension.
11. The illumination system according to claim 10 ,
wherein said first dimension has a value of 2a,
wherein said second dimension has a value of 2b, and
wherein a and b are half widths of a ellipsoid.
12. An illumination system comprising:
an extended light source that emits radiant power in a spatial angle element Ω(α), wherein a indicates an aperture angle, and wherein said light source has a density distribution having a shape;
a collector that collects said radiant power up to a first maximum aperture angle α max(1) , wherein said collector includes a plurality of rotationally-symmetric mirror shells positioned one inside another around a common axis of rotation;
a plane to be illuminated having an area A and a numerical aperture NA, wherein said numerical aperture NA defines a second aperture angle α (2) ;
a first geometric flux G 1 being defined by said shape and said first maximum aperture angle α max(1) ; and
a second geometric flux G 2 being defined by said area A and said second aperture angle α (2) ,
wherein said first geometric flux G 1 is more than 15% greater than said second geometric flux G 2 , and
wherein said collector has a central shading and a first minimum aperture angle α min(1) assigned thereto.
13. The illumination system of claim 12 , wherein said first geometric flux G 1 is less than 300% of said second geometric flux G 2 .
14. The illumination system of claim 12 , wherein said first geometric flux G 1 is less than 200% of said second geometric flux G 2 .
15. The illumination system of claim 12 , wherein said first geometric flux G 1 is less than 130% of said second geometric flux G 2 .
16. The illumination system of claim 12 , wherein said light source is a discharge plasma source.
17. A method comprising:
(A) illuminating a mask with light from an illumination system that includes:
a light source that emits radiant power in a spatial angle element Ω(α), wherein α indicates an aperture angle, and wherein said light source has a density distribution having a shape;
a collector that collects said radiant power up to a first maximum aperture angle α max(1) , a first geometric flux G 1 being defined by said shape and said first maximum aperture angle α max(1) ;
a plane to be illuminated having an area A and a numerical aperture NA, wherein said numerical aperture NA defines a second aperture angle α (2) ; and
a second geometric flux G 2 being defined by said area A and said second aperture angle α (2) ,
wherein said first geometric flux G 1 is more than 15% greater than said second geometric flux G 2 ; and
(B) imaging said mask onto a light-sensitive object to produce a microelectronic component.
18. A projection exposure system comprising:
(a) an illumination system having:
an extended light source that emits radiant power in a spatial angle element Ω(α), wherein α indicates an aperture angle, and wherein said light source has a density distribution having a shape;
a collector that collects said radiant power up to a first maximum aperture angle α max(1) , wherein said collector includes a plurality of rotationally-symmetric mirror shells positioned one inside another around a common axis of rotation;
a plane to be illuminated having an area A and a numerical aperture NA, wherein said numerical aperture NA defines a second aperture angle α (2) ;
a first geometric flux G 1 being defined by said shape and said first maximum aperture angle α max(1) ; and
a second geometric flux G 2 being defined by said area A and said second aperture angle α (2) ,
wherein said first geometric flux G 1 is more than 15% greater than said second geometric flux G 2 ; and
(b) a projection objective, wherein said illumination system is for illuminating a mask positioned in or near said plane, and wherein said projection objective is for imaging said mask on a light-sensitive object.