WO2008040410A1 - Installation de microlithographie à éclairage par projection - Google Patents

Installation de microlithographie à éclairage par projection Download PDF

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Publication number
WO2008040410A1
WO2008040410A1 PCT/EP2007/006823 EP2007006823W WO2008040410A1 WO 2008040410 A1 WO2008040410 A1 WO 2008040410A1 EP 2007006823 W EP2007006823 W EP 2007006823W WO 2008040410 A1 WO2008040410 A1 WO 2008040410A1
Authority
WO
WIPO (PCT)
Prior art keywords
projection exposure
exposure apparatus
correction
immersion objective
immersion
Prior art date
Application number
PCT/EP2007/006823
Other languages
German (de)
English (en)
Inventor
Aksel GÖHNERMEIER
Reiner Garreis
Original Assignee
Carl Zeiss Smt Ag
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from DE200610046675 external-priority patent/DE102006046675A1/de
Application filed by Carl Zeiss Smt Ag filed Critical Carl Zeiss Smt Ag
Publication of WO2008040410A1 publication Critical patent/WO2008040410A1/fr

Links

Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70—Microphotolithographic exposure; Apparatus therefor
    • G03F7/70216—Mask projection systems
    • G03F7/70341—Details of immersion lithography aspects, e.g. exposure media or control of immersion liquid supply
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70—Microphotolithographic exposure; Apparatus therefor
    • G03F7/70216—Mask projection systems
    • G03F7/70308—Optical correction elements, filters or phase plates for manipulating imaging light, e.g. intensity, wavelength, polarisation, phase or image shift
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70—Microphotolithographic exposure; Apparatus therefor
    • G03F7/70483—Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
    • G03F7/70591—Testing optical components
    • G03F7/706—Aberration measurement

Definitions

  • the invention relates to microlithographic projection exposure systems, as used for the production of highly integrated electrical circuits and other microstructured components.
  • the invention relates to projection exposure apparatus designed for immersion operation.
  • Integrated electrical circuits and other microstructured devices are typically fabricated by applying a plurality of patterned layers to a suitable substrate, which may be a silicon wafer, for example.
  • a suitable substrate which may be a silicon wafer, for example.
  • a photoresist which is suitable for light of a certain wavelength range, e.g. Light in the deep ultraviolet spectral range (DUV, deep ultraviolet), is sensitive.
  • DUV deep ultraviolet
  • the thus coated wafer is exposed in a projection exposure apparatus.
  • Pattern of structures which is on a mask, on the photoresist using a projection lens displayed. Since the magnification is generally less than 1, such projection lenses are often referred to as reduction lenses.
  • the wafer After developing the photoresist, the wafer is subjected to an etching process, whereby the layer is patterned according to the pattern on the mask. The remaining photoresist is then removed from the remaining parts of the layer. This process is repeated until all layers are applied to the wafer.
  • the immersion liquid and thus the bubbles contained in it are in the immediate vicinity of the image plane of the immersion objective, the effects of the bubbles on the optical image can be serious.
  • WO 2005/064409 A2 proposes applying a cover that can be removed again directly after the exposure on the light-sensitive layer.
  • the thickness of the cover is chosen so that bubbles and other impurities in the immersion liquid are kept so far away from the image plane that they can no longer cause serious disturbances.
  • the spherical aberrations are detected by means of known manipula- corrected. This may be, for example, a movable lens along the optical axis.
  • the object of the invention is to specify a projection exposure apparatus which increases the flexibility in the use of covers on photosensitive layers in connection with immersion operation.
  • This object is achieved according to the invention by a projection exposure apparatus with an immersion objective with which a pattern can be imaged onto a photosensitive layer and which is designed for an immersion mode in which an immersion liquid is located between the immersion objective and the photosensitive element.
  • the projection exposure apparatus further comprises optical correction means for reducing aberrations caused by applying a transparent cover which is directly applied to the photosensitive layer, so that the immersion liquid does not contact the photosensitive layer.
  • the correction device has a correction element which can be installed and removed in the immersion objective without the immersion objective having to be disassembled.
  • the invention is based on the finding that it does not make sense to correct relatively strong aberrations, which are caused by thick covers, exclusively by the hitherto known, generally continuously adjustable manipulators. Instead, it is proposed to provide a correction device with a correction element, which is installed or removed depending on whether the exposure is to be performed with a cover on the photosensitive layer. This makes it possible for different operators of projection exposure equipment who want to perform the exposure with or without coverage, the in principle to offer the same immersion objective. If an operator wishes to carry out the exposure in his system with a cover on the photosensitive layer, the correction element will be the one after assembly and adjustment of the immersion objective, but before the start of operation and preferably even before the delivery of the immersion objective to the operator built into the immersion objective. For operators who do not want to use a cover, the correction element will not be installed.
  • the immersion objective it is also possible to design the immersion objective so that in a operation without cover, a "correction element" is required, which must be expanded for operation with cover.
  • a correction is then only required for operation without cover.
  • This variant is preferable if one can assume that the immersion objective usually operates without coverage.
  • the placeholder element has the same effect as the correction element, apart from the desired correction effect as such.
  • a replacement holder may be provided.
  • the correction element is a spacer with which sockets of adjacent optical elements are held at a distance predetermined by the spacer.
  • the distance between adjacent optical elements can be changed by a larger amount in an abrupt manner.
  • a fine correction can be performed by means of known manipulators by slightly displacing one or both of the affected optical elements along the optical axis.
  • the correction element is an optical correction element that is exposed to the projection light during operation of the system.
  • a correction of the aberrations caused by the cover is also by means of mirrors possible.
  • an optical correction element are refractive optical elements.
  • the optical element may be a lens, but also a (substantially) plane-parallel plate, of which one or both planar surfaces are suitably aspherized.
  • the deviations of the aspheric optical surface from a plane surface may be less than 1000 nm or even less than 100 nm. For a 2 ⁇ m thick cover, the deviations may be e.g. between 30 nm and 50 nm.
  • the deviations of the optical surfaces of the correction element and a placeholder element without correction effect are preferably at all surface points with orthogonal coordinates (x, y) smaller than 1000 nm, preferably smaller than 100 nm, in the z-direction.
  • an aspherical correction element should be built state in or near a pupil plane of the immersion objective.
  • a correction element is also a plane-parallel plate into consideration, which is arranged in the installed state in or near a field plane of the immersion objective.
  • Suitable as a field level here is above all an intermediate image plane, but also the image plane.
  • FIG. 1 shows a meridional section through a projection exposure apparatus according to the invention in a highly schematic representation with an immersion objective and a correction device;
  • Figure 2 is an enlarged view of the image side
  • FIG. 1 shows a meridional section through a microlithographic projection exposure apparatus designated as a whole in a highly schematic representation.
  • the projection exposure apparatus 10 has a lighting device 12 for generating projection light 13, which includes a light source 14, an illumination optics indicated at 16 and a diaphragm 18.
  • the illumination optics 16 makes it possible to set different illumination angle distributions.
  • the projection exposure apparatus 10 further includes an immersion objective 20 which includes an aperture AS as well as a multiplicity of optical elements, of which only a few lenses are indicated by way of example in FIG. 1 and are designated Ll to L6 for the sake of clarity.
  • the immersion objective 20 serves to image a mask 24, which can be arranged in an object plane 22 of the immersion objective 20, onto a photosensitive layer 26, which is arranged in an image plane 28 of the immersion objective 20.
  • the photosensitive layer 26 may be e.g. to act a photoresist, which is applied to a wafer 30.
  • the lenses L 1 and L 2 are associated schematically with actuation systems A 1 and A 2, with which the lenses L 1 , L 2 can be moved along the Z-axis.
  • the actuator systems A1, A2 preferably comprise individually actuatable actuators, eg piezoelectric elements, but may also or additionally offer the possibility of a manual adjustment. Since such actuator systems are well known in the prior art, the explanation of further details is omitted.
  • a correction device designated as a whole by 34, which comprises a plate P and a replacement holder EH.
  • the plate P is aspherized on its image-side optical surface 35, which is greatly exaggerated in FIG. 1 for reasons of recognizability.
  • the deviations from a plane surface are less than 100 nm.
  • the replacement holder EH With the aid of the replacement holder EH, it is possible to lead the plate P out of the beam path of the immersion objective 20 without the entire immersion objective 20 having to be dismounted for this purpose. Details of a possible mechanical structure of the correction device 34 can be found in US 2005/0134972 A1, the disclosure content of which is fully incorporated in the present application.
  • cover 36 which is applied directly to the photosensitive layer 26.
  • the cover is formed by a layer of constant thickness consisting of a material transparent to the projection light.
  • the cover 36 ensures that gas bubbles 40 or other particles in the immersion liquid 38 of the light-sensitive layer 26 can not come so close that they lead to serious disturbances in the imaging of the mask 24 there.
  • the thickness of the layer 36 is chosen so that the distance of the gas bubbles 40 from the photosensitive layer 26 is sufficiently large.
  • a plane-parallel plate Compared with a state in which the entire space between the photosensitive layer 26 and the image-side last lens L6 is filled with immersion liquid 38, such a plane-parallel plate generates aberrations. Specifically, these are spherical aberrations, primarily defocused. In addition, there are also higher order errors that adversely affect the imaging properties.
  • the aspherical surface 35 of the plate P is shaped so that the above-mentioned aberrations caused by the cover 36 are corrected as much as possible. Remaining errors can be corrected with the Al and A2 actuator systems. Thus, it becomes possible to lithographically produce even smaller structures on the wafer 30.
  • the plate P would produce a kind of overcompensation and thus itself represent a cause of aberrations. Therefore, an adjustment is made by using the replacement holder EH an exchange plate is introduced into the beam path, which has no aspherical surface.
  • the replacement plate has the property of compensating for the action of the plate P except for the effect of the aspherical surface 35.
  • cover 36 with a different thickness or different refractive index is to be used, remaining errors can be corrected with the actuator systems A1 and A2. If covers 36 with widely varying thicknesses are to be used, the use of a different correction plate may also be considered (if necessary in addition).

Abstract

L'invention concerne une installation de microlithographie à éclairage par projection qui comprend un objectif immergé (20) par lequel l'image d'un motif (24) peut être formée sur une couche photosensible (26). L'objectif immergé (20) est conçu pour fonctionner en immersion, par le fait qu'un liquide d'immersion (38) est situé entre l'objectif immergé et la couche photosensible. L'installation d'éclairage par projection présente en outre un dispositif de correction (34) qui diminue les erreurs de formation d'image provoquées par l'application d'un masque (36) qui peut être appliqué directement sur la couche photosensible (26) de telle sorte que le liquide d'immersion (38) ne soit pas en contact avec la couche photosensible (26). Le dispositif de correction présente un élément de correction qui peut être incorporé et démonté dans l'objectif immergé (20) sans devoir démonter ce dernier.
PCT/EP2007/006823 2006-09-29 2007-08-02 Installation de microlithographie à éclairage par projection WO2008040410A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US84811806P 2006-09-29 2006-09-29
US60/848,118 2006-09-29
DE200610046675 DE102006046675A1 (de) 2006-09-29 2006-09-29 Mikrolithopraphische Projektionsbelichtungsanlage
DE102006046675.6 2006-09-29

Publications (1)

Publication Number Publication Date
WO2008040410A1 true WO2008040410A1 (fr) 2008-04-10

Family

ID=38654546

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2007/006823 WO2008040410A1 (fr) 2006-09-29 2007-08-02 Installation de microlithographie à éclairage par projection

Country Status (1)

Country Link
WO (1) WO2008040410A1 (fr)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5789734A (en) * 1993-05-14 1998-08-04 Canon Kabushiki Kaisha Exposure apparatus that compensates for spherical aberration of an image forming device
EP1431826A2 (fr) * 2002-12-09 2004-06-23 Carl Zeiss SMT AG Objectif de projection, en particulier pour la microlithographie, et méthode de réglage d'un objectif de projection
WO2004053596A2 (fr) * 2002-12-10 2004-06-24 Carl Zeiss Smt Ag Procede de reglage d'une propriete optique souhaitee d'un objectif de projection et installation d'eclairage de projection microlithographique

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5789734A (en) * 1993-05-14 1998-08-04 Canon Kabushiki Kaisha Exposure apparatus that compensates for spherical aberration of an image forming device
EP1431826A2 (fr) * 2002-12-09 2004-06-23 Carl Zeiss SMT AG Objectif de projection, en particulier pour la microlithographie, et méthode de réglage d'un objectif de projection
WO2004053596A2 (fr) * 2002-12-10 2004-06-24 Carl Zeiss Smt Ag Procede de reglage d'une propriete optique souhaitee d'un objectif de projection et installation d'eclairage de projection microlithographique

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
LAURENT MARINIER, YURI AKSENOV, ROB MORTON, DAVID VAN STEENWINCKEL, PETER ZANDBERGEN: "Anti-bubble topcoat for immersion lithography", PROC. OF THE SPIE, vol. 5753, May 2005 (2005-05-01), pages 527 - 536, XP002457991 *

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