EUV exposure apparatus with reflective elements having reduced influence of temperature variation

• US 9,746,778 B2
• Filed: 03/15/2016
• Issued: 08/29/2017
• Est. Priority Date: 07/30/2010
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV), CARL Zeiss SMT GmbH (Carl-Zeiss-Stiftung)
• Original Assignee: ASML Netherlands BV (ASML Holding NV), CARL Zeiss SMT GmbH (Carl-Zeiss-Stiftung)
• Inventors: Baer, Norman, Loering, Ulrich, Natt, Oliver, Wittich, Gero, Laufer, Timo, Kuerz, Peter, Limbach, Guido, Hembacher, Stefan, Walter, Holger, Kwan, Yim-Bun-Patrick, Hauf, Markus, Stickel, Franz-Josef, Van Schoot, Jan
• Primary Examiner(s): Iacoletti, Michelle M
• Application Number:
  US15/070,872
• Publication Number:
  US 20160195818A1
• Time in Patent Office: 532 Days
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: G02B 17/0647 using more than three curved mirrors G02B17/0668, G02B17/0694 take precedence
• CPC Class Codes: G02B 27/0043 in projection exposure systems, e.g. microlithographic systems
• CPC Class Codes: G02B 3/00 Simple or compound lenses
• CPC Class Codes: G02B 5/00 Optical elements other than lenses light guides G02B6/00; optical logic elements G02F3/00
• CPC Class Codes: G02B 5/08 Mirrors vehicle mirrors involving special optical features B60R1/08
• CPC Class Codes: G02B 5/0816 Multilayer mirrors, i.e. having two or more reflecting layers G02B5/0883, G02B5/0891 take precedence
• CPC Class Codes: G02B 5/0891 Ultraviolet [UV] mirrors apparatus for microlithography exposure G03F7/70; X-ray multilayer structures G21K1/06
• CPC Class Codes: G02B 7/1815 with cooling or heating systems cooling arrangements for laser mirrors H01S3/0401
• CPC Class Codes: G03B 27/542 for copying cameras, reflex exposure lighting
• CPC Class Codes: G03F 7/7015 Details of optical elements
• CPC Class Codes: G03F 7/702 Reflective illumination, i.e. reflective optical elements other than folding mirrors, e.g. extreme ultraviolet [EUV] illumination systems
• CPC Class Codes: G03F 7/70233 Optical aspects of catoptric systems, i.e. comprising only reflective elements, e.g. extreme ultraviolet [EUV] projection systems
• CPC Class Codes: G03F 7/70316 Details of optical elements, e.g. of Bragg reflectors, extreme ultraviolet [EUV] multilayer or bilayer mirrors or diffractive optical elements
• CPC Class Codes: G03F 7/70825 Mounting of individual elements, e.g. mounts, holders or supports workpiece or mask holders G03F7/707
• 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
• CPC Class Codes: G21K 1/062 Devices having a multilayer structure
• CPC Class Codes: G21K 2201/061 characterised by a multilayer structure
• CPC Class Codes: G21K 2201/064 having a curved surface

Abstract

A projection lens of an EUV-lithographic projection exposure system with at least two reflective optical elements each comprising a body and a reflective surface for projecting an object field on a reticle onto an image field on a substrate if the projection lens is exposed with an exposure power of EUV light, wherein the bodies of at least two reflective optical elements comprise a material with a temperature dependent coefficient of thermal expansion which is zero at respective zero cross temperatures, and wherein the absolute value of the difference between the zero cross temperatures is more than 6K.

Claims

1. A projection lens of an EUV-lithographic projection exposure system including a reticle and an illumination system for illuminating the reticle, the projection lens comprising:

a plurality of reflective optical elements M_i;

said reflective optical elements M_i having respective bodies MB_i defining respective reflective surfaces MS_i for projecting an object field on said reticle onto an image field on a substrate when said projection lens is exposed with an exposure power of EUV light at a wavelength lying in a wavelength range of less than 50 nm, the EUV light being reflected from said reticle when illuminated by said illumination system;

at least one reflective optical element M_k of said reflective optical elements M_i including a material having a temperature dependent coefficient of thermal expansion which is zero at a zero cross temperature T_0k;

the body MB_k of the optical element M_k being semitransparent to an IR radiation;

said at least one reflective optical element M_k with its body MB_k including a coating C on or on almost its entire surface of the body MB_k thereof;

the coating C reflecting IR radiation inside said body MB_k; and

,

said projection lens further comprising an IR light source or comprising an optical arrangement forming an IR light path to couple IR radiation into the body MB_k comprising the coating C.

2. The projection lens of claim 1, wherein the IR light source or the optical arrangement comprises an element selected from the group consisting of:

laser, IR-diode, filament, lens, refractive element, diffractive element, light guide and optical fiber.

3. The projection lens of claim 1, wherein the body MB_k comprises a surface area not coated with the coating C;

or, comprises a surface area with a coating being semitransparent to the IR radiation, for coupling in the IR radiation into the body MB_k.

4. The projection lens of claim 3, wherein the surface area is arranged on the side of the body MB_k which comprises the reflective surface MS_k.

5. The projection lens of claim 4, wherein the surface area surrounds the reflective surface MS_k.

6. The projection lens of claim 4, wherein a construction space nearby the reflective surface MS_k is illuminated by the IR radiation and the EUV light.

7. The projection lens of claim 3, wherein the surface area comprises a surface roughness to scatter the IR radiation into the body, or the surface area comprises a diffractive structure to distribute the IR radiation within the body MB_k by diffraction.

8. The projection lens of claim 1, wherein the coating comprises a metal.

9. The projection lens of claim 1, wherein the IR source is arranged outside the projection lens or outside the EUV-lithographic projection exposure system.

10. A mirror comprising:

a body MB_k and a reflective surface MS_k;

a material having a temperature dependent coefficient of thermal expansion which is zero at a zero cross temperature T_0k;

the body MB_k of the optical element M_k being semitransparent to an IR radiation;

the body MB_k comprising a coating C on its surface;

wherein the coating C reflects IR radiation inside the body MB_k;

wherein the mirror is adapted for a projection lens of an EUV-lithographic projection exposure system for projecting an object field on a reticle onto an image field on a substrate when the projection lens is exposed with an exposure power of EUV light with a wavelength lying in a wavelength range of less than 50 nm;

wherein the body MB_k comprises at least one surface area not coated with the coating C, or comprises at least one surface area with a coating being semitransparent to the IR radiation, for coupling in the IR radiation into the body MB_k; and

,

said at least one surface area comprises a surface roughness to scatter the IR radiation into the body, or the surface area comprises a diffractive structure to distribute the IR radiation within the body MB_k by diffraction.

11. The mirror of claim 10, wherein the coating comprises a metal.

12. The mirror of claim 10, wherein the surface area is arranged on the side of the body MB_k which comprises the reflective surface MS_k.

13. The mirror of claim 12, wherein the surface area surrounds the reflective surface MS_k.

14. A projection lens of an EUV-lithographic projection exposure system, comprising:

at least one mirror including;

a body MB_k and a reflective surface MS_k;

a material having a temperature dependent coefficient of thermal expansion which is zero at a zero cross temperature T_0k;

the body MB_k of the optical element M_k being semitransparent to an IR radiation;

the body MB_k comprising a coating C on its surface;

wherein the coating C reflects IR radiation inside the body MB_k;

wherein the mirror is adapted for a projection lens of an EUV-lithographic projection exposure system for projecting an object field on a reticle onto an image field on a substrate when the projection lens is exposed with an exposure power of EUV light with a wavelength lying in a wavelength range of less than 50 nm;

wherein the body MB_k comprises at least one surface area not coated with the coating C, or comprises at least one surface area with a coating being semitransparent to the IR radiation, for coupling in the IR radiation into the body MB_k; and

,

said at least one surface area comprises a surface roughness to scatter the IR radiation into the body, or the surface area comprises a diffractive structure to distribute the IR radiation within the body MB_k by diffraction.