OPTICAL ARRANGEMENT

• US 20020126400A1
• Filed: 12/29/2000
• Published: 09/12/2002
• Est. Priority Date: 12/29/1999
• Status: Active Grant

• Current Assignee: CARL Zeiss SMT AG (Carl-Zeiss-Stiftung)
• Original Assignee: Carl-Zeiss-Stiftung
• Inventors: Wagner, Christian, Muller-Rissmann, Wemer, Holderer, Hubert, Hummel, Wolfgang, Becker, Jochen, Xalter, Stefan, Von Bünau, Rudolf
• Granted Patent: US 6,466,382 B2
• Time in Patent Office: Days
• US Class Current: 359/820
• CPC Class Codes: G03F 7/70058 Mask illumination systems
• CPC Class Codes: G03F 7/70216 Mask projection systems
• CPC Class Codes: G03F 7/70891 Temperature
• CPC Class Codes: G03F 7/70958 Optical materials or coatings, e.g. with particular transmittance, reflectance or anti-reflection properties

Abstract

An optical arrangement, in particular a projection exposure system for microlithography, has, in particular, a slit-shaped image field or a non-rotational-symmetric illumination. As a result, an optical element (101) is exposed in a non-rotational-symmetric manner to the radiation of the light source (110, 111, 112). The optical element (101) has an absorbing coating (104, 105). The absorption of the coating (104, 105) is distributed in such a manner that it is non-rotation-symmetrical in a manner that is at least approximately complementary to the intensity distribution of the exposure to the radiation (107, 108, 109) of the light source (110, 111, 112). As a result of the energy absorbed in the coating (104, 105), an additional heating of the optical element (101) takes place that results in a better non-rotational-symmetric temperature distribution and, consequently, a compensation for light-induced imaging errors.

Claims

1. An optical arrangement, in particular projection exposure system for microlithography, in particular having slit-shaped illumination, having at least one light source that emits radiation and an optical element that is heated by exposure to the radiation, wherein the optical element is exposed to the emitted radiation of the light source with non-rotational-symmetric intensity distribution;

wherein

a) the optical element (1;

101) has an absorbing coating (4, 5;

104, 105) having a spatial distribution such that

b) the absorption of the coating (4, 5;

104, 105) is non-rotational-symmetric in an at least approximately complementary manner to the intensity distribution of the exposure to the radiation (7;

107, 108, 109) of the light source (10;

110, 111, 112).

2. The optical arrangement as claimed in claim 1, wherein the absorbing coating comprises at least two portions (4, 5) between which there remains a non-absorbingly coated region (3) whose dimension transversely to the axis of the radiation (7) is smaller in at least one direction than the cross section of the radiation (7) measured in the same direction.

3. The optical arrangement as claimed in claim 1 or 2, wherein the absorbing coating (4, 5;

104, 105) has an absorptive power, varying over its surface, for wavelengths of the radiation (7;

107, 108, 109) of the light source (10;

111, 112).

4. The optical arrangement as claimed in claim 3, wherein the absorbing coating (4, 5;

104, 105) varies in its layer thickness.

5. The optical arrangement as claimed in claim 3 or 4, wherein the absorbing coating varies spatially in its absorption coefficient.

6. The optical arrangement according to one of claims 3 to 5, wherein the absorbing coating (4, 5;

104, 105) has the highest absorptive power in the region that is nearest the centre of the surface of the optical element exposed to the radiation.

7. The optical arrangement according to one of the preceding claims, wherein the light source has a projection light source (110) and a compensating light source (111, 112), wherein the radiation (108, 109) of the compensating light source (111, 112) is directed at the absorbing coating (104, 105).

8. The optical arrangement according to one of the preceding claims, wherein a spatial distribution of the absorbing coating (104, 105) is such that optical image errors of at least one other optical element are compensated for by the non-rotational-symmetric absorption of the radiation (7;

107, 108, 109) of the light source (10;

110, 111, 112) in an optical element.