WO2009135556A1 - Optique de projection pour la microlithographie comportant un dispositif de correction d'intensité - Google Patents

Optique de projection pour la microlithographie comportant un dispositif de correction d'intensité Download PDF

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Publication number
WO2009135556A1
WO2009135556A1 PCT/EP2009/001684 EP2009001684W WO2009135556A1 WO 2009135556 A1 WO2009135556 A1 WO 2009135556A1 EP 2009001684 W EP2009001684 W EP 2009001684W WO 2009135556 A1 WO2009135556 A1 WO 2009135556A1
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WO
WIPO (PCT)
Prior art keywords
intensity
projection optics
correction
plane
field
Prior art date
Application number
PCT/EP2009/001684
Other languages
German (de)
English (en)
Inventor
Damien Fiolka
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
Application filed by Carl Zeiss Smt Ag filed Critical Carl Zeiss Smt Ag
Publication of WO2009135556A1 publication Critical patent/WO2009135556A1/fr

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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
    • G03F7/70308—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
    • G03F7/70058—Mask illumination systems
    • G03F7/70083—Non-homogeneous intensity distribution in the mask plane
    • 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
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/0025—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for optical correction, e.g. distorsion, aberration

Definitions

  • the invention relates to a projection optics for microlithography. Furthermore, the invention relates to an optical system with such a projection optical system, a projection exposure apparatus with such an illumination system, a method for producing a microstructured or nanostructured component using such a projection exposure apparatus and a component produced by the method.
  • projection optics for microlithography for imaging an object field in an object plane into an image field in an image plane
  • an intensity correction device for correcting an intensity exposure of a field illumination
  • the intensity correction means is arranged in the region of a correction field plane of the projection optics, wherein the correction field plane is arranged downstream of the object plane.
  • Corresponding intensity correction devices are known from some of the prior art documents already mentioned above for the arrangement, in particular, near the object plane or in a field plane of the illumination optics. According to the invention, it has now been recognized that a variation of the illumination intensity on the object field itself can be tolerated if this variation is corrected in the downstream correction field level, so that the unwanted variation of the illumination intensity distribution in the illumination of the image field is no longer present. As has been recognized, this correction can therefore be realized in a field plane of the projection optics arranged downstream of the object plane. This simplifies the structural design of the illumination optics, which is connected upstream of the projection optics according to the invention.
  • an illumination intensity distribution perpendicular to an object displacement direction can be corrected, that is to say perpendicular to the direction in which the object to be imaged is displaced during operation of a projection exposure apparatus whose part is the projection optics according to the invention.
  • the intensity correction device can have at least one correction element for influencing the intensity of imaging light, which has a distance to the correction field plane that is less than 100 mm, preferably less than 50 mm. This distance can also be less than 5 mm. This minimizes unwanted illumination angle influence of the intensity correction device.
  • the intensity correction device can be arranged in the region of the image plane of the projection objective.
  • the image plane serves as a correction field level. Arrangements can be used which are known from the prior art for corresponding intensity correction devices which are arranged in the object plane of a projection exposure apparatus.
  • the projection optics can have an intermediate image plane between the object plane and the image plane, wherein the intensity correction device can be arranged in the region of this intermediate image plane.
  • the intensity correction device can in particular be arranged precisely in this intermediate image plane, since the region around this intermediate plane of the projection optics can be kept free of other components of the projection optics. With such an arrangement, it is possible to realize the correction effect of the intensity correction device without undesired illumination angle influencing. The influence of the intensity correction device on the illumination intensity is then decoupled from the influence on the illumination angle.
  • the intensity correction device can be positioned so that the main rays are perpendicular to the plane predetermined by the intensity correction device come to mind.
  • the imaging light will then nevertheless be practically telecentric to the intensity correction device, which minimizes illumination angle influence of the intensity correction device in this case.
  • the intensity correction device in this case is arranged in a plane which encloses an angle different from 0 with the intermediate image plane.
  • the intensity correction device can have at least two correction elements which are arranged in different correction field levels arranged downstream of the object plane. This combines the advantages of an intensity correction device with two correction elements, namely the least possible influence on the illumination angle, with the advantages of an intensity correction device with exactly one correction element, namely small size. Insofar as the field with different magnification is reproduced in the two correction field levels, the correction elements are adapted to these different magnifications in such an intensity correction device.
  • the intensity correction device can have as a correction element at least one attenuation element for imaging light.
  • a weakening element can act as a diaphragm or as a filter.
  • the dazzle effect can be absorbing or reflective.
  • the attenuation element can be designed as at least one aperture. With such an attenuation element, a well-defined attenuation of the imaging light can be achieved. - A -
  • the diaphragm may have a sharp, the correction field plane next adjacent diaphragm edge. This minimizes an undesirable influence of the intensity correcting device on an illumination angle distribution.
  • the aperture edge can be created by a corresponding cut of the aperture.
  • the attenuation element may be contoured perpendicular to the object displacement direction. With such a contouring is a perpendicular to the object displacement direction selectively influencing the intensity of the imaging light.
  • the contouring can be predetermined as a result of a corresponding calibration measurement and, for example, be brought about by a defined material processing of the attenuation element, for example by laser machining or by wire erosion.
  • the attenuation element may include a plurality of finger diaphragms adjacent to each other and displaceable relative to each other in the object displacement direction. Examples of such finger panel designs are in the initially mentioned prior art. This makes it possible to adapt a contouring of the attenuation element perpendicular to the object displacement direction to the respective illumination conditions.
  • the intensity correction device can have two attenuation elements that have contouring, which are embodied in particular mirror-symmetrically with respect to one another with respect to a plane perpendicular to the object displacement direction. Such a design results in that illumination angle effects of the individual attenuation elements cancel each other out, so that as a result no or at most a small effect of the intensity correction device results on the illumination angle.
  • the projection optics can have a measuring device for measuring the intensity of an object field illumination. This can be used to control the intensity correction device and to correspondingly influence the imaging light.
  • the measuring device can be in signal connection with the intensity correction device. This can be used in particular for a feedback control of illumination parameters.
  • the measuring device can be designed such that it measures an intensity distribution of the object field illumination perpendicular to the object displacement direction.
  • the measurement result of the measuring device can then be used as a direct input variable for controlling the intensity correction device for homogenizing an intensity distribution perpendicular to the object displacement direction.
  • the intensity correction device can have a finger diaphragm displacement device which is in signal connection with the measuring device. In this way, the intensity correction device can be adjusted automatically depending on the result of the measuring device.
  • the intensity correction device may comprise a changing device with a plurality of changeover correction elements. It can then be used that correction element that is adapted to the particular lighting conditions.
  • the intensity correction device can have a control device which is in signal connection with the change device and / or the measuring device. Again, this can be used to automate a lighting adjustment using the intensity corrector.
  • FIG. 1 is a schematic sectional view of a projection exposure apparatus for microlithography with illumination optics and projection optics;
  • FIG. 2 shows the projection optics of the projection exposure apparatus according to FIG. 1 with different arrangement variants of an intensity correction device for correcting an intensity exposure of a field illumination of the projection exposure apparatus, likewise in meridional section;
  • FIG. 3 shows a plan view of an embodiment of the intensity correction device
  • FIG. 4 shows, in a representation similar to FIG. 3, a further embodiment of an intensity correction device
  • FIG. 6 shows a further embodiment of an intensity correction device
  • FIG. 7 shows illumination of a wafer with the projection exposure apparatus in a meridinal section running in parallel to the section according to FIGS. 1 and 2, wherein an intensity correction device according to FIGS. 3 or 5 is arranged in front of the wafer, and wherein in addition Section of the intensity correction device and the wafer is shown enlarged again;
  • FIG. 8 shows, in a representation similar to FIG. 7, the illumination of the wafer, in front of which an intensity correction device according to FIGS. 4 or 6 is arranged;
  • FIG. 9 shows, in a representation similar to FIG. 7, the illumination of an intermediate image plane of the projection optical system of the projection exposure apparatus, wherein an intensity correction device according to FIGS. 3 or 5 is arranged in the intermediate image plane and wherein a section of the intensity intensity enlarges again. Correction device is shown;
  • FIG. 10 shows, in a representation similar to FIG. 7, the illumination of an intermediate image plane of the projection optics of the projection exposure apparatus, wherein an intensity correction device according to FIGS. 4 or 6 is arranged in the intermediate image plane;
  • FIGS. 11 to 13 further variants of projection optics with schematically indicated further embodiments or positioning possibilities of the intensity correction devices.
  • An illumination system 2 of the projection exposure apparatus 1 has, in addition to a radiation source 3, an illumination optics 4 for the exposure of an object field 5
  • an object plane 6 a reticle 7 arranged in the object field 5 is exposed, which carries a structure to be projected with the projection exposure apparatus 1 for the production of microstructured or nanostructured semiconductor components.
  • the object field 5 is rectangular in the illustrated embodiments. An arcuate object field is also possible. A certain x-value along the object field 5 is also referred to as field height.
  • a projection optical system 8 is used to image the object field 5 into an image field 9 in an image plane 10.
  • the structure on the reticle 7 is imaged onto a non-sensitive layer of a wafer 11 arranged in the image plane 10 in the region of the image field 9.
  • the radiation source 3 is an EUV radiation source with an emitted useful radiation in the range between 5 nm and 30 nm. It can be a plasma source, for example a GDPP source (plasma discharge by gas discharge, or plasma discharge) to an LPP source (plasma generation by laser, laser produced plasma) act. Other EUV radiation sources, such as those based on a synchrotron, are possible.
  • EUV radiation 12 emanating from the radiation source 3 is bundled by a collector 13.
  • a corresponding collector is known for example from EP 1 225 481 A.
  • the EUV radiation 12 propagates through an intermediate focus plane 14 before it encounters a field facet mirror 15.
  • the field facet mirror 15 is arranged in a plane of the illumination optics 4, which is optically conjugate to the object plane 6.
  • the EUV radiation 12 is hereinafter also referred to as illumination light or as imaging light.
  • the EUV radiation 12 is reflected by a pupil facet mirror 16.
  • the pupil facet mirror 16 is arranged in a plane of the illumination optics 4, which is optically conjugate to a pupil plane of the projection optics 8.
  • an imaging optical assembly in the form of a transmission optical system 17 in the order of the beam path for the EUV Radiation 12 designated mirrors 18, 19 and 20 are not shown in the drawing field facets of the field facet mirror 15 superimposed on each other in the object field 5.
  • the last mirror 20 of the transfer optics 17 is a "grazing incidence mirror.”
  • the transfer optics 17, together with the pupil facet mirror 16, are also referred to as successive optics for transferring the EUV radiation 12 from the field facet mirror 15 to the object field 5.
  • a Cartesian xyz coordinate system is used in the drawing below.
  • the x-axis in Fig. 1 is perpendicular to the plane to the viewer.
  • the y-axis extends in Fig. 1 to the right.
  • the z-axis extends in Fig. 1 upwards.
  • the reticle 7, which is held by a reticle holder, not shown, and the wafer 11, which is held by a wafer holder, not shown, are scanned synchronously in the y-direction during the operation of the projection exposure apparatus 1.
  • An object displacement direction of the wafer 11 is indicated by a directional arrow 21 in FIG.
  • FIG. 2 shows an embodiment of the projection optics 8.
  • the projection optics 8 are purely reflective and have a total of eight mirrors M 1 to M 8, which are numbered consecutively in the sequence of the beam path of the imaging light 12.
  • the mirror design of the projection optical system 8 according to FIG. 2 is known from US Pat. No. 6,710,917 B2 and shown there in FIG.
  • the mirror surfaces of the mirrors M1 to M8 are indicated as mirror surfaces symmetrical about an optical axis 22. In fact, this is the representation of the auxiliary or material surfaces necessary for the mathematical description of the mirror surfaces. In reality, the reflection surfaces of the mirrors M1 to M8 are present where they are exposed to the imaging light 12.
  • first intermediate image plane 23 of the projection optics 8 Between the mirrors M2 and M3 is a first intermediate image plane 23 of the projection optics 8. Between the mirrors M6 and M7 is a second intermediate image plane 24 of the projection optics 8. These two intermediate image planes 23, 24 and the image plane 10 provide Correction field levels of the projection optics 8, which are the object level 6 downstream. In the area of these correction field levels 10, 23, 24, intensity correction devices may be arranged, which will be explained below. It is possible to arrange an intensity correction device directly in one of the intermediate image planes 23, 24. The intensity correction device can alternatively be arranged in the region of the image plane 10, namely in front of the wafer 11, ie on the side of the wafer 11 facing the last mirror M8, at a distance which is less than 50 mm, preferably less than 5 mm.
  • FIG. 3 shows a first embodiment of an intensity correction device 25, which can be arranged in the first intermediate image plane 23 of the projection optical unit 8.
  • the intensity correction device 25 has a correction element 26 for influencing the intensity of the imaging light 12, which has a rectangular bundle cross section in the first intermediate image plane 23.
  • the correction element 26 represents an attenuation element for the imaging light 12 and has a plurality of finger apertures 27, which are again shown somewhat enlarged in FIG. 3 above the correction element 26.
  • the finger panels 27 are adjacent to each other and relative to each other in the object displacement direction, ie in the y direction displaced. This displacement results in a contouring 28 of the correction element 26 constructed from the plurality of finger panels 27.
  • the finger panels 27 can be displaced by a finger-diaphragm displacement device 29 (see FIG. T). This has a plurality of actuators, which are each assigned to the individual finger panels 27 for displacement of these in the y-direction.
  • the finger diaphragm displacement device 29, which is shown schematically in FIG. 2 is in signal communication with a correction control device 30 in a manner not shown.
  • the correction control device 30 is in turn connected to a measuring device 31 in a manner not shown in signal communication.
  • the measuring device 31 measures the intensity exposure of the illumination of the object field 5. To this end, the measuring device 31 can detect either unused scattered light emanating from the object field 5 of the imaging light 12 or unused imaging light 12 transmitted through the reticle 7. Alternatively or additionally, it is possible for the measuring device 31 to detect radiation of different wavelengths carried with the imaging light 12.
  • the intensity correction device 25 operates as follows: The intensity distribution of the exposure of the object field 5 by the imaging light 12 is determined by the measuring device I (x) dependency measured. Where this I (x) dependence exits predetermined tolerance limits, an activation of the assigned finger shutters 27 is caused at the x positions, at which too high intensity values are measured, so that they are moved further into the radiation beam of the imaging light 12 and in order to reduce the intensity load on the wafer 11 at these x-positions.
  • the correction controller 30 causes the x this position associated finger aperture 27 from the beam path of the imaging light 12 are moved out, so that more imaging light 12 strikes the wafer 11.
  • the y-integrated wafer illumination is uniformized in its intensity dependence I (x), so that a sensitive to the imaging light 12 coating on the wafer 11 regardless of their x-position y-integrated, ie along the object displacement direction 21, with the same imaging light dose is applied. This results in a uniformed illumination of the wafer 11.
  • FIG. 4 shows a further embodiment of an intensity correction device 32, which can be used in the projection optical system 8, for example in the second intermediate image plane 24 or directly in front of the wafer 11.
  • the intensity correction device 32 has, in addition to the correction element 26, a second correction element 33 which is inserted into the radiation beam of the imaging light 12 of FIG the first correction element 26 opposite side can be retracted.
  • a contouring 34 of the correction element 33 is exactly opposite to the contouring 28 of the correction element 26, so mirror-symmetrically with respect to the xz-median plane between the correction elements 26, 33 executed.
  • the correction element 33 is constructed, just like the correction element 26, from a plurality of finger diaphragms 27, which can be actuated displaceably.
  • the intensity correction device 32 can also be arranged directly in front of the wafer 11 in the beam path of the imaging light 12, as also schematically illustrated in FIG.
  • intensity correction devices 25, 32 instead of the finger-diaphragm embodiments of the intensity correction devices 25, 32, corresponding intensity correction devices 35, 36 may be provided without finger diaphragms.
  • FIG. 5 shows the intensity correction device 35, which corresponds to the intensity correction device 25, but is designed without finger diaphragms.
  • a correction element 37 of the intensity correction device 35 is designed as a single diaphragm which, where it projects into the radiation beam of the imaging light 12, has the contouring 28, which was generated, for example, by laser material removal from a first straight diaphragm edge.
  • the contouring 28 of the intensity correction device 35 is static, so it can not be changed during operation of the projection exposure system 1 without aperture change.
  • FIG. 6 shows the intensity correction device 36 which, in addition to the correction element 37, has a further correction element 38 in accordance with the intensity correction device 32.
  • Both correction elements 37 and 38 have static contours 28, 34, as explained above in connection with the embodiment of FIG. 5.
  • the further correction element 38 is introduced from the side opposite the correction element 37 into the radiation beam of the imaging light 12, as explained above in connection with the intensity correction device 32.
  • the contour 34 of the correction element 38 is, as in the case of the intensity correction device 32, in turn mirror-symmetrical to the xz center plane.
  • FIG. 7 shows the effect of the intensity correction device 25 in the event that it is arranged directly in front of the wafer 11 instead of the intensity correction device 32.
  • the radiation beam of the imaging light 12 which impinges on the wafer 11 is shown by the example of two main beams 39, 40 spaced apart from one another in the y-direction.
  • the main beam 39 is associated with two edge beams 41, 42 which emphasize the extreme illumination angles and with the peripheral beams 43, 44 corresponding to the main beam 40.
  • An image field point 45 which is shown on the wafer 11 on the left in FIG. 7, is thus illuminated by an imaging light pencil 46, which is bounded by the marginal rays 41, 42.
  • An image field point 47 which is shown on the right in FIG. 7 and is spaced apart from the image field point 45 in the object displacement direction 21, is illuminated by an imaging light pencil 48 bounded by the marginal rays 43, 44.
  • FIG. 7 shows an enlarged detail of the diaphragm section of the correction element 26, which is directly adjacent to the image field point 47.
  • this diaphragm section is exactly one of the finger shutters 27.
  • the intensity correction device 35 is used, it is a section of the correction element 37.
  • This section of the correction element 26 or 37, adjacent to the image field point 47, is designed as a sharp diaphragm edge 49. This is achieved by a corresponding bevel of the leading end of this section of the correction element or 37.
  • This sharp-edged design of the diaphragm edge 49 causes the diaphragm edge 49 in the imaging light pencil 48 to influence all illumination directions almost simultaneously, Thus, both the marginal ray 43 and the marginal ray 44. Dimming the imaging light 12 through this portion of the correction element 26 or 37 has at most a small influence on an illumination angle distribution for the image field point 47.
  • This at most slight influence of the diaphragm edge 49 on the illumination angle distribution of Imaging light 12 depends on the sharp edge of the diaphragm edge 49 and on the distance of the diaphragm edge 49 from the image plane 10.
  • FIG. 8 accordingly shows the influence of the intensity correction devices 32 and 36 on the illumination angle distribution of the imaging light 12, if these intensity correction devices 32, 36 are again arranged directly in front of the wafer 11.
  • the rays of the imaging light 12 are again denoted as above in connection with FIG. 7.
  • the correction element 26 or 37 shown on the right in FIG. 8 has an influence on the illumination angle distribution, this results from the fact that FIG Preferably, the marginal ray 44 is dimmed, but the marginal ray 43 still passes the correction element 26 or 37 and therefore still reaches the wafer 11.
  • the illumination angle influence by the second correction element 33 or 38 is exactly mirror-image, so that the marginal ray 41 is preferably dimmed there, whereas the marginal ray 42 in the case of an illumination angle influence of the correction element 33 and 38, respectively is still transmitted to the wafer 11.
  • the intensity correcting means 35, 36 may comprise changing means each having a plurality of such correction elements. This is illustrated in FIG. 2 in conjunction with the intensity correction device 35 by means of a change device 50 and in conjunction with the intensity correction device 36 with reference to two changeover devices 51, which each have a plurality of changeover correction elements 53.
  • the changing devices 50 to 52 can be designed, for example, in the manner of a diaphragm carousel.
  • the changeover devices 51, 52 belonging to the intensity correction device 36 with the two symmetrically executed correction elements 37, 38 each have pairs of change correction elements 53 with symmetries 28, 34 which are symmetrical to one another and which are each used to block the imaging light 12 come. It can be specified via the measuring device 31 and the control device 30 which of these pairs of alternating correction elements 53 is used in each case.
  • a residual illumination angle influencing resulting from the finite extent of the correction elements 26, 33, 37, 38 in the z direction can be further minimized or be completely eliminated when the correction elements 26, 33, 37, 38 is provided with a sharp-edged diaphragm edge 54, as shown in the enlarged detail in Fig. 9 below the example of the correction elements 26, 37.
  • the diaphragm edge 54 is arranged exactly in the intermediate image plane 23 or 24.
  • 11 to 13 show further embodiment variants of projection optics 55, 56 and 57, in which the embodiments of intensity correction devices explained above can be used.
  • the optical design of the projection optics 55 corresponds to that which is explained in FIG. 3 of US Pat. No. 6,710,917 B2.
  • the projection optics 55 likewise have eight mirrors M1 to M8, which, as in the case of the projection optics 8, are numbered consecutively in the sequence of the imaging beam path. Also in the illustration according to FIG. 11, beyond the true reflection surfaces of the mirrors M1 to M8, the parent surfaces used for the mathematical description of reflection surfaces are also shown.
  • an intermediate image plane 58 is arranged, which is comparable to the intermediate image plane 24 of the projection optics 8 accessible from both sides. In the intermediate image plane 58, therefore, any of the above-described embodiments of intensity correction devices 25, 32, 35, 36 can be used.
  • a further diaphragm plane 59 is shown in dashed lines, in which one of the above-explained variants of intensity correction devices 25, 32, 35 or 36 can be arranged.
  • the projection optics 56 according to FIG. 12 correspond in their optical design to that which is explained in FIG. 11 of WO 2007/031 271 A1.
  • This is a free-form surface design with a total of six mirrors Ml to M6, which are numbered in the order of the imaging beam path.
  • an intermediate image plane 60 which is suitable for arranging an intensity correction device of the type described above.
  • Tensticianskorrektur Wales be used. Schematically, the situation is shown in FIG. 12, in which in each case an intensity correction device 25 or 32 with exactly one correction element 26 or 37 are used.
  • One of these intensity correction devices 25 and 32 is in the intermediate image plane 60 and the other is arranged immediately in front of the image plane 10.
  • This overall arrangement can also be understood as exactly one intensity correction device with two correction elements 25 and 32, which are arranged in different correction field planes downstream of the object plane 6, namely in the intermediate image plane 60 and adjacent to the image plane 10.
  • FIG. 13 shows the optical design of the projection optics 57.
  • the beam path is shown in each case as three individual beams 61 emanating from five object field points superimposed on one another in the y direction in FIG. 13, the three individual beams 61 being one of these five object field points belong, are each assigned to three different lighting directions for the five object field points.
  • the individual beams 61 are first reflected by a first mirror M1 and then by further mirrors M2, M3, M4, M5 and M6.
  • the projection optics 57 according to FIG. 13 thus has six reflecting mirrors. These mirrors carry a highly reflective coating for the wavelength of the illumination light, if required by the wavelength, for example in the EUV.
  • the illumination optics 4 and the projection optics 57 it is also possible to emit radiations having wavelengths which differ greatly from one another, since these optics have substantially achromatic properties. It is thus possible, for example, to drive an optical laser in these optics or to operate an autofocusing system, wherein at the same time the illuminating light is operated at a wavelength which differs greatly from its operating wavelength.
  • an alignment laser can operate at 632.8 nm, at 248 nm, or at 193 nm while operating simultaneously with an illumination light in the range between 10 and 30 nm.
  • the mirrors M1, M3 and M5 have a convex basic shape, so can be described by a convex best-adapted surface.
  • the third mirror M3 has a convex basic shape.
  • the mirrors M2, M4 and M6 have a concave basic shape, so can be described by a concave best-fit surface. In the following description, such mirrors are simply referred to as convex or concave.
  • the convex mirror M3 ensures a good Petzval correction in the projection optics 57.
  • Those individual beams 61 which start from spaced object field points and are assigned to the same illumination direction, run convergent into the projection optics 57 between the object plane 6 and the first mirror M1.
  • the design of the projection optics 57 can be adapted so that the same illumination directions for the individual field beams 61 associated with the object field points also run divergent or parallel to one another between these components.
  • the last variant corresponds to an object-side telecentric beam path.
  • the individual beams 61 belonging to a specific illumination direction of the five object field points unite in a pupil plane 62 of the projection optics 57, to which the mirror M3 is arranged adjacent.
  • This mirror M3 is therefore also referred to as a pupil mirror.
  • an aperture diaphragm for limiting the illumination light beam may be arranged in the pupil plane 62.
  • This aperture diaphragm can be provided directly on the mirror M3 by a mechanical and exchangeable diaphragm or else in the form of a corresponding coating.
  • the mirrors M1 to M4 image the object plane 6 into an intermediate image plane 63.
  • the inter-image-side numerical aperture of the projection optics 57 is 0.2.
  • the mirrors M1 to M4 form a first partial imaging optics of the projection optics 57 with a reducing magnification of 3.2x.
  • the subsequent mirrors M5 and M6 form a further partial imaging optics of the projection optics 57 with a decreasing magnification of 2.5x.
  • In the region of the intermediate image plane 63 is a passage opening 64 formed in the sixth mirror M6, through which the illumination or imaging light 12 passes in the reflection from the fourth mirror M4 toward the fifth mirror M5.
  • the fifth mirror M5 in turn has a central passage opening 65 through which the radiation beam passes between the sixth mirror M6 and the image plane 10.
  • the fifth mirror M5, which together with the sixth mirror M6 thecommunitiesl. Imaging light 12 images from the intermediate image plane 63 in the image plane 10 is disposed in the vicinity of a further pupil plane 66 of the projection optics 57 conjugate to the first pupil plane 62.
  • the further pupil plane 66 is located in the beam path of the imaging light 12 between the fifth mirror M5 and the sixth mirror M6, so that a physically accessible diaphragm plane exists at the location of the further pupil plane 66.
  • an aperture diaphragm may also be arranged in this diaphragm plane, as described above in connection with the aperture diaphragm in the area of the pupil plane 62.
  • the projection optics 57 has a centered obscuration diaphragm in one of the pupil planes 62, 66. As a result, the sub-beams of the projection beam path assigned to the central passage openings 64, 65 in the mirrors M6, M5 are obscured. Therefore, the design of the projection optics 57 is also referred to as a design with central pupil obscuration.
  • An excellent single beam 61 which connects a central object field point with a centrally illuminated point in the entrance pupil of the projection optics 57 in the entrance pupil plane 62, is also referred to below as the main ray 67 of a central field point.
  • the main ray 67 of the central field point includes approximately a right angle from the reflection on the sixth mirror M6 with the image plane 10, thus runs approximately parallel to the z-axis of the projection optics 57. This angle is greater than 85 ° in any case.
  • the image field 9 is rectangular. Parallel to the x-direction, the image field 9 has an extension of 13 mm. Parallel to the y-direction, the image field 9 has an extension of 1 mm.
  • the image field 9 is located centrally behind the fifth mirror M5.
  • a radius R of the passage opening 65 results from:
  • R - D + dw - NA.
  • D is the diagonal of the image field 9.
  • d w is the working distance of the mirror M5 of the
  • NA is the image-side numeric
  • All six mirrors M1 to M6 of the projection optics 57 are designed as freeform surfaces that can not be described by a rotationally symmetrical function. Other embodiments of the projection optics 57 are also possible, in which at least one of the mirrors M1 to M6 has such a free-form reflecting surface.
  • Z is the arrow height of the freeform surface parallel to a Z axis, which may be parallel to the z 'axis of FIG. 4, for example.
  • c is a constant corresponding to the vertex curvature of a corresponding asphere
  • k corresponds to a conic constant of a corresponding asphere.
  • C j are the coefficients of the monomials X m Y n .
  • the values of c, k and C j are determined based on the desired optical properties of the mirror within the projection optics 57.
  • the order of the monomial, m + n can be varied as desired. A higher-order monomode can lead to a design of the projection optics with better image aberration correction, but is more complicated to compute, m + n can take values between 3 and more than 20.
  • the image-side numerical aperture NA is 0.5.
  • the size of the image field is 1 x 13 mm 2 .
  • the decreasing magnification is 8x.
  • the image field 9 is rectangular.
  • the wavelength of the illumination light is 13.5 nm.
  • Principal rays converge convergent into the projection optics from the object plane 6.
  • An aperture stop for edge illumination light boundary is arranged at the mirror M3.
  • the z-distance between the object plane 6 and the image plane 10 is 1,500 mm.
  • the object-image offset is 0.42 mm. 5.9% of the areas illuminated in the pupil planes are obscured.
  • the projection optics 57 has a wavefront error (rms) in units of the wavelength of the illumination light 12 of 0.02.
  • the distortion is 12 nm.
  • the field curvature is 9 nm.
  • the main beam angle at the central object field point is 5.9 °.
  • the mirror M1 has a size (x / y) of 117 x 61 mm 2 .
  • the mirror M2 has a size of 306 x 143 mm 2 .
  • the mirror M3 has a size of 80 x 77 mm 2 .
  • the mirror M4 has a size of 174 x 126 mm 2 .
  • the mirror M5 has a size of 253 x 245 mm 2 .
  • the mirror M6 has a size of 676 x 666 mm 2 .
  • the sequence of principal ray incident angles of the principal ray 67 of the central object field point on the mirrors M1 to M6 is 16.01 °, 7.14 °, 13.13 °, 7.21 °, 0.0 ° and 0.0 °.
  • the sequence of the maximum angles of incidence on the mirrors M1 to M6 is 22.55 °, 9.62 °, 13.90 °, 10.16 °, 16.23 °, 4.37 °.
  • the sequence of the bandwidths of the angles of incidence on the mirrors M1 to M6 is 13.12 °, 5.07 °, 1.58 °, 6.10 °, less than 16.23 ° and less than 4.37 °.
  • the working distance in the object plane 6 is 100 mm.
  • the working distance in the image plane 10 is 40 mm.
  • the ratio between the distance of the object plane 6 to the mirror Ml and the distance of the object plane 6 to the mirror M2 is 4.25.
  • Between the adjacent mirrors M2 - M3, M4 - M5, M5 - M6 and between the mirror M6 and the image plane 10 is in each case a distance which is greater than 40% of the z-distance between the object plane 6 and the image plane 10.
  • the mirror Ml and M4 have a minimum distance of the used reflection surface to the nearest, free from this mirror imaging beam path (free board), which is smaller than 25 mm.
  • the optical design data of the reflecting surfaces of the mirrors M1 to M6 of the projection optics 57 can be seen in the following tables.
  • the first of these tables indicates the reciprocal of the vertex curvature (radius) and a distance value (thickness) corresponding to the z-spacing of adjacent elements in the beam path, starting from the object plane 6, to the optical components and to the aperture stop.
  • the second table gives the coefficients C j of the monomials X m Y n in the free-form surface equation given above for the mirrors M1 to M6.
  • At the end of the second table is still the amount in mm, along which the respective mirror, based on a mirror reference design decentered (Y-decenter) and twisted (X-rotation) was. This corresponds to the parallel displacement and the tilt in the free-form surface design method described above. It is shifted in the y-direction and tilted about the x-axis.
  • the twist angle is given in degrees.
  • Intensity correction devices of the type described above for the intensity correction device 25, 32, 35 and 36 may be arranged in the intermediate image plane 63 or in front of the image plane 10 in the projection optics 57.
  • the correction elements explained above in connection with the intensity correction means represent attenuation elements for the imaging light 12, which are designed as diaphragms.
  • the reticle 7 and the wafer 11 are initially provided and arranged on the respective holder.
  • the wafer 11 carries a photosensitive coating for the imaging light 12.
  • at least a portion of the reticle 7 is projected onto the wafer 11 by means of the projection exposure apparatus 1.
  • the exposed photosensitive layer is developed on the wafer 11.

Abstract

L'invention concerne une optique de projection (8) pour la microlithographie, servant à reproduire un champ d'objet (5) situé dans un plan d'objet (6), dans un champ d'image situé dans un plan d'image (10). Un dispositif de correction d'intensité (25; 32; 35; 36) sert à corriger l'intensité d'un éclairage de champ. Le dispositif de correction d'intensité (25; 32; 35; 36) est disposé dans la zone d'au moins un plan de champ de correction (23, 24, 10) de l'optique de projection (8). Le plan de champ de correction est disposé en aval du plan d'objet (6). Il en résulte une optique de projection permettant une correction de variations non souhaitées de paramètres d'éclairage, notamment une correction de variations non souhaitées d'une distribution d'intensité d'éclairage de champ.
PCT/EP2009/001684 2008-05-09 2009-03-10 Optique de projection pour la microlithographie comportant un dispositif de correction d'intensité WO2009135556A1 (fr)

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US5176108P 2008-05-09 2008-05-09
DE102008001694.2 2008-05-09
US61/051,761 2008-05-09
DE200810001694 DE102008001694A1 (de) 2008-05-09 2008-05-09 Projektionsoptik für die Mikrolithografie

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CN116243563A (zh) * 2022-09-09 2023-06-09 上海镭望光学科技有限公司 光刻机照明均匀性校正装置的校正方法

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DE102012216494A1 (de) * 2012-09-17 2013-08-14 Carl Zeiss Smt Gmbh Verfahren zum Betreiben eines Projektionsbelichtungssystems für die EUV-Lithographie und Projektionsbelichtungssystem
WO2017029383A1 (fr) * 2015-08-20 2017-02-23 Carl Zeiss Smt Gmbh Installation de lithographie extrême ultraviolet et procédé y relatif

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US5677757A (en) * 1994-03-29 1997-10-14 Nikon Corporation Projection exposure apparatus
WO2005040927A2 (fr) * 2003-10-18 2005-05-06 Carl Zeiss Smt Ag Dispositif permettant de regler une dose d'eclairage sur une couche photosensible, et procede de production microlithographique d'elements microstructures
US20060139608A1 (en) * 2004-12-28 2006-06-29 Asml Holding N.V. De-focus uniformity correction
WO2006128613A1 (fr) * 2005-06-02 2006-12-07 Carl Zeiss Smt Ag Objectif de projection de microlithographie
US20070024835A1 (en) * 2005-08-01 2007-02-01 Kuo-Chun Huang Method for improving illumination uniformity in exposure process, and exposure apparatus

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EP0952491A3 (fr) 1998-04-21 2001-05-09 Asm Lithography B.V. Appareil lithographique
DE10138313A1 (de) 2001-01-23 2002-07-25 Zeiss Carl Kollektor für Beleuchtugnssysteme mit einer Wellenlänge < 193 nm
JP2001060546A (ja) 1999-08-20 2001-03-06 Nikon Corp 露光方法及び露光装置
DE10052289A1 (de) 2000-10-20 2002-04-25 Zeiss Carl 8-Spiegel-Mikrolithographie-Projektionsobjektiv
CN103076723A (zh) 2005-09-13 2013-05-01 卡尔蔡司Smt有限责任公司 微光刻投影光学系统

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US5677757A (en) * 1994-03-29 1997-10-14 Nikon Corporation Projection exposure apparatus
WO2005040927A2 (fr) * 2003-10-18 2005-05-06 Carl Zeiss Smt Ag Dispositif permettant de regler une dose d'eclairage sur une couche photosensible, et procede de production microlithographique d'elements microstructures
US20060139608A1 (en) * 2004-12-28 2006-06-29 Asml Holding N.V. De-focus uniformity correction
WO2006128613A1 (fr) * 2005-06-02 2006-12-07 Carl Zeiss Smt Ag Objectif de projection de microlithographie
US20070024835A1 (en) * 2005-08-01 2007-02-01 Kuo-Chun Huang Method for improving illumination uniformity in exposure process, and exposure apparatus

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116243563A (zh) * 2022-09-09 2023-06-09 上海镭望光学科技有限公司 光刻机照明均匀性校正装置的校正方法
CN116243563B (zh) * 2022-09-09 2024-04-02 上海镭望光学科技有限公司 光刻机照明均匀性校正装置的校正方法

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