WO2004040378A2 - Dispositif d'eclairage destine a un systeme d'exposition a projection pour microlithographie - Google Patents

Dispositif d'eclairage destine a un systeme d'exposition a projection pour microlithographie Download PDF

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Publication number
WO2004040378A2
WO2004040378A2 PCT/EP2003/011000 EP0311000W WO2004040378A2 WO 2004040378 A2 WO2004040378 A2 WO 2004040378A2 EP 0311000 W EP0311000 W EP 0311000W WO 2004040378 A2 WO2004040378 A2 WO 2004040378A2
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WO
WIPO (PCT)
Prior art keywords
integrator
rod
unit
lighting device
light source
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Application number
PCT/EP2003/011000
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German (de)
English (en)
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WO2004040378A3 (fr
Inventor
Markus DEGÜNTHER
Stig Bieling
Johannes Wangler
Original Assignee
Carl Zeiss Smt Ag
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Application filed by Carl Zeiss Smt Ag filed Critical Carl Zeiss Smt Ag
Priority to AU2003276050A priority Critical patent/AU2003276050A1/en
Publication of WO2004040378A2 publication Critical patent/WO2004040378A2/fr
Publication of WO2004040378A3 publication Critical patent/WO2004040378A3/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
    • G03F7/70058—Mask illumination systems
    • G03F7/70075—Homogenization of illumination intensity in the mask plane by using an integrator, e.g. fly's eye lens, facet mirror or glass rod, by using a diffusing optical element or by beam deflection

Definitions

  • the invention relates to an illumination device for illuminating an illumination field with the light from a primary light source, in particular to an illumination device for an icrolitography projection exposure system which works with a high-pressure mercury lamp as the primary light source.
  • the performance of projection exposure systems for the microlithographic production of semiconductor components and other finely structured components is largely determined by the imaging properties of the projection objectives.
  • the image quality and the wafer throughput that can be achieved with the system are essentially determined by properties of the lighting system upstream of the projection objective. This must be able to block the light from a primary light source, such as a mercury High-pressure lamp or a laser, to be prepared with the highest possible efficiency and to generate the most uniform possible intensity distribution in an illumination field of the lighting device.
  • a primary light source such as a mercury High-pressure lamp or a laser
  • it should be possible to set different lighting modes (settings) on the lighting system for example conventional lighting with different degrees of coherence or ring field lighting to generate off-axis, oblique lighting. It is desirable that the properties of the illuminating light, in particular the intensity in the illuminating field, do not change, or change only slightly, in different settings.
  • a lighting device of the type mentioned at the outset which works with a mercury short-arc lamp for the i-line (working wavelength 365 nm) and has an integrator unit which mixes or homogenizes the light thereof Light source serves.
  • the integrator unit has (at least) a cuboidal integrator rod made of quartz glass with a rectangular entry surface and four reflecting side surfaces oriented perpendicular to one another and parallel to the optical axis, in which the light passing through is mixed by multiple internal reflections.
  • the discharge lamp of the light source has an almost spherical radiation characteristic and a finite extent, which leads to a much higher etendue (phase space volume) compared to laser light sources.
  • the light conductance of this light source is significantly higher than the light conductance of a laser.
  • the lamp is arranged in a focal point of an elliptical mirror, which collects the emitted light in the region of the second focal point of the elliptical mirror.
  • an aperture serving as a shutter is arranged in the area of the focal point.
  • the light distribution in the area of the shutter is imaged on the entry surface of the integrator rod via condenser optics, so that in the plane a more or less round light spot is created on the entrance surface.
  • integrator rods or rod integrators are used, the entry surface of which has a high aspect ratio between the rod width and the rod height, which can be 2: 1 or larger, for example. It can happen that the expansion of the light spot is larger than the rod height. This effect leads to vignetting of the light and is particularly pronounced in small settings that produce a large light spot. The light from the light source can therefore no longer be completely coupled into the integrator system, which can result in a reduction in the system transmission and in connection with this a reduction in the wafer throughput. Since, in addition, the beam angles occurring at the entry surface are generally dependent on the distance from the optical axis, vignetting leads to what is known as elliptical pupil illumination.
  • an intensity distribution in the pupil planes is referred to which has a greater overall intensity in the quadrants arranged around a horizontal axis than in the quadrants arranged around a vertical axis.
  • a pronounced pupil ellipticity can lead, for example, to horizontal and vertical structures of a mask to different resolving power for the different structure directions (CD variations).
  • the invention has for its object to provide a lighting device of the type mentioned, which is characterized by a high total transmission.
  • the total transmission should preferably have only a weak dependency on the set lighting modes.
  • the illumination device should enable the most uniform possible illumination of pupil planes with low pupil ellipticity.
  • a lighting device is distinguished by the fact that it has at least one premixing unit which is arranged in front of the entry surface of an integrator rod and has at least one reflection surface which runs obliquely to the side surfaces of the integrator rod.
  • the pupil ellipticity can be greatly reduced and possibly largely eliminated. This means that there is no need for a cover at the rod entry. This in turn increases the overall transmission of the system.
  • the integrator unit has at least one cuboidal integrator rod with a rectangular entry surface and four reflecting side surfaces oriented perpendicular to one another and parallel to the optical axis.
  • Such integrator units can be adapted particularly well to wafer scanners with a rectangular field of unequal side lengths.
  • the invention makes it possible to ensure, with a high coupling efficiency, pupil illuminations with low ehipticity behind a rod integrator with a rectangular cross section.
  • the coupling efficiency is given by the ratio between the illuminated part of the entrance area and the area of the light spot in the entrance plane of the integrator rod.
  • the ellipticity of a pupil illumination is a scalar quantity and is determined by forming the ratio of the total intensities of the quadrants arranged around a horizontal axis and the total intensities of the quadrants arranged around a vertical axis. These quadrants are delimited by two straight lines which intersect in the middle of the pupil illumination, are perpendicular to each other and each form an angle of 45 ° to the horizontal direction.
  • the width of an integrator rod in the X direction, the (lower) height of the integrator rod in the Y direction and the longitudinal direction running parallel to the optical axis are defined as the Z direction.
  • the inventor has found that a major cause of the observed pupil ellipticity lies in the fact that the pupils at the rod entry - except on the optical axis - are illuminated in a dipole-like manner, the field dependence of the illumination being rotationally symmetrical to the optical axis.
  • the intensities are only reflected on the X and Y axes. As a result, it is not possible in a rectangular bar for intensity to be directed from a quadrant centered around the X axis to a quadrant centered around the Y axis, or vice versa. The intensities thus remain “trapped” in their respective quadrants.
  • the invention overcomes this limitation. Due to the at least one reflection surface of the premixing unit, which runs obliquely to the side surfaces of the rod integrator and thus obliquely to the X and Y axes, the intensity of an incident light beam is not necessarily directed into a quadrant connected via mirror symmetry, but rather into an adjacent, um the other axis centered quadrants are steered. This enables mixing across the quadrant boundaries, which is referred to below as “azimuthal mixing”.
  • the pupil ellipticity is significantly reduced, whereby an at least largely ellipticity-free illumination pupil can be generated by suitable dimensioning. Since the at least one subsequent integrator rod with a rectangular cross-section works essentially in an angle-preserving manner, the largely ellipticity-free illumination pupil present at the outlet of the premixing unit also remains behind receive the following integrator rod.
  • a rectangular integrator rod for example due to the non-ideal surface quality of the totally Appropriate countermeasures can be taken if the reflecting interfaces produce a change in pupil ellipticity between entry and exit.
  • suitable measures are shown in DE 100 65 198, the disclosure of which is made the content of this description.
  • the effect of the premixing unit on the pupil ellipticity can optionally be combined with the effect of the measures described there in order to obtain an at least largely ellipticity-free illumination pupil at the outlet behind the light mixing unit.
  • premixing units are preferred in which the at least one reflection surface is flat. This brings advantages in terms of production technology and makes it possible in a simple manner to adapt the overall cross section of the premixing unit to the cross section of the following integrator rod.
  • a multiplicity of, preferably flat, oblique reflection surfaces is preferably provided, in particular an even number, for example four or more.
  • the premixing unit comprises a cuboid bar arrangement with a large number of adjoining integrator rods which can essentially completely fill the cross-sectional area of the rod arrangement, for example to a high percentage of, for example, more than 90%, 95% or 98%.
  • the premixing unit, in particular the rod arrangement can have a cross section corresponding to the cross section of the entry surface. At least two of the rods have a reflection surface which is oriented obliquely to the side surfaces of the integrator rod and which brings about the azimuthal mixing.
  • Such a bar arrangement can comprise, for example, a dense packing of integrator bars which are hexagonal in cross section. Integrator bars of this type are shown, for example, in US Pat. No.
  • the rod arrangement has at least two complementary integrator rods which are essentially wedge-shaped in cross section and which complement one another to form a pair of rods with a rectangular cross section.
  • the premixing unit can comprise several such pairs of rods, which are preferably arranged symmetrically to the optical axis.
  • premixing unit in particular the rod arrangement mentioned, has an integrator rod with a square cross section centered on the optical axis.
  • This square rod does not itself introduce e-hipticity. It can be combined with rod units that have inclined reflection surfaces for azimuthal mixing of the entrance light.
  • the premixing unit in particular the rod arrangement mentioned, has an integrator rod with a hexagonal cross section centered or centerable on the optical axis.
  • the integrator rod which is hexagonal in cross section, introduces an azimuthal mixing of the entrance light.
  • the hexagon can be regular or irregular.
  • a premixing unit with a central integrator rod and four integrator rods surrounding it which overall add up to a rectangular cross section, allows good azimuthal mixing.
  • the use of a central integrator bar with a polygonal cross section proves to be particularly favorable, since it itself contributes to the azimuthal mixing.
  • the side surfaces of a polygonal integrator rod serving as reflection surfaces are arranged parallel or at an angle of 45 ° to the side surfaces of the cuboid integrator rod oriented parallel to the optical axis, particularly effective, targeted azimuthal mixing can be achieved.
  • the length of the premixing unit can be kept short and, if necessary, shortened in comparison to other embodiments described here.
  • the integrator rod and optical components of the premixing unit are preferably made of transparent material, in particular of synthetic quartz glass, for applications in the deep or vacuum ultraviolet range, for example for systems of i-line microlithography.
  • transparent mixing elements the internal reflection leading to mixing is based on total reflection at the interfaces with optically thinner media.
  • suitable, small distances between the adjacent side surfaces of rod-shaped elements can provide for total reflection conditions.
  • the principle of the invention can also be used in integrator units for light mixing in the extreme ultraviolet range (EUV), for example at wavelengths of 20 nm or less. Internally mirrored hollow integrator rods and rods can be used for this application.
  • EUV extreme ultraviolet range
  • a primary light source with finite dimensions and a large beam angle for example a high-pressure mercury lamp.
  • the primary light source is arranged in a first focal point of an elliptical mirror. Between the primary light source and a second focus of the elliptical At least one aspherical optical element with at least one aspherical surface is arranged in the mirror, the shape of which is designed such that heavy rays of the radiation emitted by the primary light source behind the aspherical optical element essentially point to a common point on the optical axis, in particular the second focal point of the elliptical Mirror, are directed.
  • This measure can increase the coupling efficiency into the integrator unit by compressing the light distribution that falls either directly or with the aid of an image into the entry surface of the integrator unit. This can be achieved by suitably designing the asphere without increasing the angular spectrum in the area of the focal point.
  • the shape of the aspherical surface can be optimized for a small conventional setting, for example.
  • an advantageous further development provides that the aspherical optical element can be displaced along the optical axis by means of a control device.
  • the aspherical optical element can thus be optimally positioned for each setting in order to achieve the desired compression of the light distribution, e.g. to reach at the location of the closure.
  • the invention also relates to a method for producing semiconductor components and other finely structured components.
  • a Reticle arranged in an object plane of a projection objective is illuminated with the aid of an illumination device which comprises an integrator unit for mixing light from a primary light source.
  • An image of the reticle is produced on a light-sensitive substrate.
  • the step of illuminating the reticle involves azimuthal mixing of light from the primary light source. The extent of the azimuthal intermixing can be adjusted so that an essentially ellipticity-free illumination is guaranteed.
  • the integrator unit comprises at least one cuboid integrator rod and the azimuthal mixing takes place in the light path in front of the integrator rod.
  • the premixing unit described in more detail above can be used for azimuthal mixing.
  • the mixing unit and integrator rod By dividing the azimuthal pupil mixing and the mixing over the field into separate components (premixing unit and integrator rod), vignetting-free lighting of rectangular lighting fields is possible.
  • FIG. 1 is a schematic illustration of a preferred exemplary embodiment of a lighting device according to the invention.
  • FIG. 2 is a schematic representation of the distribution of the light intensity in the area of a rectangular entry surface of an integrator rod
  • Fig. 3 is a schematic illustration of an illuminating pupil for explaining pupil ellipticity
  • FIG. 4 is a schematic illustration of an illumination pupil for explaining the mixing in an integrator unit
  • FIG. 5 is a schematic representation of an embodiment of a rod-shaped premixing unit
  • Fig. 6 is a schematic illustration of another embodiment of a rod-shaped premixing unit
  • FIG. 7 is a schematic illustration of another embodiment of a rod-shaped premixing unit
  • Fig. 8 is a schematic representation of the reflection of a light beam in an integrator rod with an irregular hexagonal cross section; 9 is a schematic illustration of the illumination pupil to explain the targeted mixing in an integrator rod;
  • Fig. 10 is a schematic of the distribution of heavy beams between the primary light source and a shutter plane in a conventional lighting device
  • FIG. 11 is a schematic illustration of the distribution of heavy beams between a primary light source and the shutter plane according to an embodiment of the present invention
  • FIG. 12 and 13 are diagrams showing the setting dependence of the illumination intensity in the reticle plane with conventional illumination (FIG. 9) and annular illumination (FIG. 10).
  • a mercury short-arc lamp 11 serves as the primary light source for the mercury i-line at a wavelength of 365 nm. It is arranged in one of the two focal points of an elliptical mirror 12, which collects the emitted light in the region of its second focal point 13. In this area, a shutter 14 is arranged, which is also an aperture.
  • An aspherical optical element 15 is arranged between the light source 11 and the second focal point 13, which optimizes the heavy beam distribution in the area of the Closure 14 causes and which is axially displaceable along the optical axis 16 of the system. Its function is explained in more detail in connection with FIGS. 7 and 8. There are also embodiments with other light sources.
  • the following lens 20 has a first lens group 21, a concave first axicon lens 22, a convex second axicon lens 23 and a second lens group 24.
  • Adjustment means 25, 26 allow axial displacement of the axicon lens 23 and one optical element of the two - th lens group 24.
  • the distance of the axicon lenses 22, 23 from one another can be adjusted and thus the ring field character of the pupil illumination in the intermediate pupil plane 27 can be changed.
  • a zoom effect for changing the diameter of the pupil illumination that is to say the degree of coherence ⁇ , is achieved.
  • the lighting modes that can be achieved by manipulating the lens 20 are also referred to here as lighting settings.
  • Exemplary embodiments for the lens 20 are contained, for example, in EP 687 956 B1 (corresponding to US Pat. No. 5,675,401), the features of which are made the content of this description by reference.
  • the elliptical collector mirror 12, the first lens 20 and the second lens 30 form a condenser lens 35, which has only optical components with a rotationally symmetrical effect with respect to the optical axis 16.
  • the condenser optics 35 images the primary light source 11 onto the entry surface 41 of the integrator unit 40. No shading diaphragm is arranged between the condenser optics 35 and the entry surface 41, so that the entire rod entry surface 41 can be used for coupling light.
  • the integrator unit 40 centered around the optical axis 16 serves to mix light from the light source 11 in order to achieve homogeneous illumination of the illumination field.
  • the integrator unit comprises a cuboid-shaped integrator rod 42, which consists of synthetic quartz glass, has a rectangular entry surface 43, a rectangular exit surface 44 of the same size and four totally reflecting side surfaces 45, 46, 47, 48 (cf. FIG. 2).
  • a premixing unit 50 which has a rectangular cross section corresponding to the cross section of the integrator rod and comprises a plurality of totally reflecting reflection surfaces running obliquely to the side surfaces 45 to 48 and parallel to the optical axis 16.
  • the exit surface 44 of the integrator rod 42 or the integrator unit 40 forms an intermediate field level 55, in which a masking system (reticle masking system, REMA) 56 is arranged.
  • the following lens 60 also referred to as a REMA lens, images the masking system 56 into the image plane 65 of the lens 60.
  • the plane 65 coincides with the object plane of a subsequent projection objective 67 and is also referred to as the reticle plane, in which a structure-bearing mask 66 (the reticle or the photomask) can be arranged.
  • the subsequent projection objective 67 depicts the structure of the mask in its image plane 68, in which a substrate coated with a light-sensitive layer, for example a semiconductor wafer, can be arranged.
  • Both the structure-bearing mask 66 and the light-sensitive substrate are carried by a positioning and exchange unit (not shown) which, in addition to exchanging the elements, also allows the elements to be scanned during the exposure.
  • the objective 60 contains a first lens group 61, a pupil plane 62, a second lens group 63 and a third lens group 64, between which a deflection mirror 69 is arranged. Exemplary embodiments of the objective 60 are given, for example, in DE 195 48 805 A1 (corresponding to US 5,982,558) and DE 196 53 983 A1 (corresponding to US Serial Number 09/125621).
  • An embodiment of the projection lens 67 is contained in DE 199 42 281. The relevant features of these documents are made by reference to the content of this description.
  • the transmission efficiency is the ratio between the light intensity emitted by the primary light source 11 and the light intensity arriving in the illumination field in the reticle plane 65.
  • the light coupling efficiency is the ratio of the difference between the total radiation power present in the area of the entrance area minus the radiation power “rejected” by vignetting to the total radiation power in the entrance plane.
  • the light coupling efficiency thus increases the less radiation power in the area of the entry area 41
  • Two effects can contribute to this loss of light, namely, on the one hand, an overexposure of the entry surface by a larger light spot compared to the rod entry and, on the other hand, masking regions of the rod entry surface by means of diaphragms the full entry surface for light entry is available on any kind of cover at the rod entry. is available.
  • the negative influences on the pupil ellipticity associated with this measure are largely or completely eliminated by the premixing unit 50.
  • FIG. 2 shows a rectangular entry surface of an undivided rod integrator, in which the ratio between width (X direction) and height (Y direction) is approximately 2: 1.
  • a circular light spot 70 generated by the condenser optics 35 is shown in dashed lines. In the example, this practically completely fills the width direction, while in the height direction above and below the rod, radiation intensity is directed past the rod entry and remains unused (vignetting).
  • the arc of the light source 11 in the exemplary embodiment has a length of 4 mm and a diameter of 7 mm.
  • the light beams emitted by the light source have 16 angles between approximately 60 ° and approximately 135 ° with respect to the optical axis.
  • the arc is imaged by the condenser optics 35 on the entry surface and generates a light spot, the maximum diameter of which, at the smallest set ⁇ value, is approximately 300% larger than the rod height.
  • the rays here have a maximum angle of approximately 18 ° with respect to the optical axis.
  • the diameter of the light spot and the beam angle on the entrance surface depend on the position of the zoom lenses and the axicon lenses in the objective 20. With conventional settings (closed axicon lenses), the size of the light spot decreases with increasing ⁇ value, which leads to an increase in light coupling efficiency with increasing ⁇ value.
  • the light intensity is coupled into the rod overall in such a way that in the areas centered around the X axis ( Quadrants 2 and 4) there is more light intensity than in the quadrants 1 and 3 centered around the Y axis (cf. FIG. 3).
  • the total intensities in the four quadrants 1, 2, 3 and 4 are determined.
  • the quadrants are delimited here by straight lines 75, 76, which are each at 45 ° to the Y axis (or to the X axis).
  • the e-hipticity results from the quotient of the total intensities in quadrants 1 and 3 centered around the Y axis and the total intensity in quadrants 2 and 4 centered around the X axis according to:
  • FIG. 4 shows a pupil divided into quadrants, in which a light beam incident in the rod is represented by an arrow 80.
  • the length of the arrow is referred to as “zenith” and in the projection of the directional arrow onto the pupil plane represents the angle between the direction of incidence and the optical axis 12.
  • an arrow leading to the edge of the pupil would have an angle of incidence of 90
  • the arrow direction is further characterized by an angle 81 between a reference direction, for example the Y axis, and the plane that an incident light beam spans with the optical axis is called azimuth.
  • the rod-shaped integrator unit 40 is modified compared to known solutions in that a premixing unit 50 of the same cross section is arranged in front of an integral integrator rod 42.
  • the integrator unit is thus divided into two axially successive sections, the ratio of the lengths of the first section 50 to the second section 42 being, for example, se can be approx. 3: 5.
  • the premixing unit 50 is designed as a cuboid bar arrangement with five adjoining integrator bars 151 to 155, each of which is at a small distance (greater than the wavelength of the light used) along its side surfaces, in order to enable total reflection within the individual bars.
  • a central rod 151 to be arranged centered around the optical axis has a square cross section, the side length of which corresponds to the height of the rod arrangement.
  • Two pairs of rods 152, 153 and 154, 155 are arranged mirror-symmetrically to the Y-axis on the left and right, the rods of which each have a wedge-shaped cross section, which in the embodiment according to FIG. 5 has the shape of a right-angled triangle.
  • the hypotenuse surfaces 156 to 159 which face one another and are arranged at a short distance from one another form flat reflection surfaces which are oriented obliquely to the side surfaces 45 to 48 of the rod integrator and are arranged mirror-symmetrically to the YZ plane.
  • the angle of attack to the X or Y axes is approx. 30 ° or 60 ° here.
  • the ratio V of the total area of the oblique reflection area to the total area of the reflection area running in the X or Y direction is approximately 0.75.
  • the ratio V should be between about 0.6 and about 0.8. If V is less than 0.6, several reflections in the rod can take place in succession without including the inclined surfaces. This reduces the efficiency of the azimuthal pupil mixing.
  • a value greater than 0.8 means that the angle of attack of the inclined surface becomes very large or very small. However, if the inclined surface is almost parallel or orthogonal to the other surfaces, this in turn reduces the effect of interpupillary mixing. For this reason, the angle of attack should be between approx. 15 ° and approx. 75 °.
  • the rods provided with inclined surfaces on the left and right of the square central rod 151' have a wedge-shaped square cross-section, in which the oblique reflection surfaces are angled at an acute angle of approx. 20 ° and a correspondingly larger angle of approx. 70 ° to the Y-axis or the X-axis.
  • sharp-angled edges, which are susceptible to damage, are avoided here, which makes simple mounting possible.
  • the pupil quadrants 1 and 3 When irradiation is rotationally symmetrical to the central axis of the rod, integrated as much energy into the pupil quadrants 1 and 3 is integrated into the first rod section, which is formed by the premixing unit 50 or 50 ', integrated via the profile of the square central piece 151 or 51'. as in the pupil quadrants 2 and 4. With a sufficient light mixture, the pupil behind this central, square rod element is by definition ellipticity-free. Due to the inclined reflection surfaces 156 to 159 in the side pieces of the premixing unit, in contrast to a rod integrator with parallel or vertical reference surfaces, the pupil is mixed azimuthally.
  • azimuthal mixing a redistribution of light energy from the quadrants centered around the X axis can take place (and vice versa) centered around the Y axis.
  • one means azimuthal mixing that, for example, portions of the light energy of the light beam 80 can be transferred to an adjacent quadrant, for example in the quadrant 3 in the vicinity of the Y axis (dash-dotted arrow 80 ').
  • FIG. 7 shows a further embodiment of a premixing unit 50 ".
  • This has a central integrator rod 151" with a hexagonal base, the edges of which are of different lengths.
  • An integrator rod with a hexagonal cross section is also referred to here as a “hexagonal integrator rod”.
  • this integrator rod is centered around the optical axis of the lighting system.
  • Two opposite side surfaces 170, 171 of the central integrator rod form the middle part of the side faces of the cuboid premixing unit 50 " pointing in the X direction, while the four further side faces are each arranged at an angle of 45 ° to these side faces.
  • These four side surfaces lie adjacent to the side surfaces of four integrator rods 162 to 165 with a wedge-shaped base, which are designed such that they form the cuboid premix unit 50 " together with the central integrator rod.
  • the hexagonal integrator rod introduces a targeted azimuthal mixing of the entry light.
  • the wedge-shaped edge wedges 162 to 165 also mix the light passing through them azimuthally. Like the central integrator rod, the edge wedges have 151 "edges with angles of 45 °, 135 ° and 90 ° and mix just as specifically as the central integrator rod, however a little less effective.
  • FIG. 9 shows that eight discrete azimuthal angles ⁇ occur in the schematic representation of the pupil plane according to FIG. 9, which are represented by the arrows 210, 211.
  • the four integrator rods 162 to 165 with a wedge-shaped base also lead to an azimuthal mixing of the entrance light, since they have oblique reflection surfaces, and in particular they also only have side surfaces which are parallel or at an angle of 45 ° or 135 ° to the side surfaces of the cuboid integrator unit 42 are arranged.
  • the cross-sectional area of the central hexagonal integrator rod with the same dimensioning of the rectangular cross-sectional surface of the premixing device 50 is larger than the cross-sectional area of a central integrator rod with a square base area, leads to better illumination of the pupil parcels, as a result of which the telecentricity error is reduced.
  • the above-described azimuthal mixing together with the quite large cross-sectional area of the central integrator rod also means that the total length of the premixing unit can be small in this embodiment.
  • the field illumination behind the premixing unit is usually not yet homogeneous. Homogenization is achieved by the subsequent rectangular integrator rod 42 of sufficient length.
  • this integrator rod preserves the distribution of the total energy in the pupil quadrants 1 and 3 or 2 and 4 and thus the largely or completely ellipticity-free pupils, which are provided by the premixing unit 40. Due to the multiple internal reflection along the length of the rod, however, the light is mixed over the entire field and thus a uniform intensity distribution at the rod outlet 44 (in the intermediate field plane 55) regardless of location.
  • the premixing device 50 If the overall length of the integrator unit is predetermined by structural constraints, then in the above embodiment of the premixing device 50 " a greater length is available for the cuboid integrator rod 42. This leads to better homogenization of the light, which in the intermediate field level 55 on the one hand means that the telecentricity errors are reduced and on the other hand the intensity curve in this level becomes almost field-independent. In other words: since the premixing unit 50 "shows better mixing behavior, the length of this unit can be kept small without significant losses in the e-hipticity. The cuboid portion can be extended to optimize the telecentricity and uniformity at the rod exit.
  • FIGS. 10 and 11 show the meridional beam path between the light source 11 and the plane of the closure 14 schematically. Due to the unavoidable shadowing by the lamp electrodes, the angular distribution in the area of the closure 14 is annular and due to the expansion of the lamp plasma, the light spot in the vicinity of the second ellipse focal point, ie in the area of the closure 14, is axial and radial extended. This “smeared” light distribution is shown in FIG. 7 using the courses of heavy beams 90.
  • the heavy beams remote from the axis are directed to the center of the closure plane, the heavy beams close to the axis aim at an axis point that is at a distance from this plane.
  • This light distribution is achieved by the objectives 20, 30 in the entry plane of the integrator unit 40. As mentioned above, part of the light is vignetted on this end face, especially with small ⁇ values.
  • the light distribution in the area of the closure 14 (ie the “object size”) for the imaging imaging optics is compressed. It is important that the angular spectrum in the area of the closure is not enlarged because this leads to an enlargement An enlargement of the setting leads to an increase in the coupling efficiency anyway (FIGS. 12 and 13).
  • a compression of the light distribution in the shutter plane without widening the angle spectrum is achieved by in a plane 91 in front of the plane an aspherical optical element 15 is arranged between the light source and the second focal point of the elliptical mirror 12.
  • the axial position is preferably selected such that the element sits as close as possible to the plane of the closure, but on the other hand beams from the upper and lower region A and B of the ellipsoid mirror 12 still g
  • the aspherical optical element which can be designed, for example, as a meniscus-shaped plate with concave surfaces facing the shutter plane, has at least one aspherical surface 92.
  • the radii of the two surfaces are approximately concentric with the center of the closure and the asphere is like this calculates that all the heavy beams 90 are aimed in the region of the center of the shutter, that is to say to the second focus of the elliptical mirror 12. It can be seen from the beam path in FIG. 11 that, on the one hand, the light in the shutter 14 is more focused and, secondly, that the light is partially Angle of incidence can be reduced, so that the annularity of the pupils in the area of the closure 14 is reduced.
  • the shape of the asphere can be optimized for a certain conventional setting, in particular a small conventional setting (with a small ⁇ value), by calculating the distribution of the heavy beam directions over the field height at a distance from the optical axis for the selected plane 91 and the asphere is designed so that the desired heavy beam distribution results.
  • the latter is preferably mounted so that it can move axially, so that the axial position of the asphere can be optimally set individually for each setting.
  • the x-axis represents different ⁇ values or settings that increase to the right, while a normalized intensity I (norm) [%] is plotted on the y-axis in the reticle plane.
  • the ⁇ value is defined here as the ratio NA Bei, 90% / NA PO, where NA Be ⁇ , 90% is the radius in the objective pupil that encloses 90% of the light provided by the lighting system (90% encircled energy), and NA PO is the radius of the objective pupil of the projection object.
  • All y values are standardized to the maximum intensity that can be achieved with a system without a premixing unit and an aspherical optical element, whereby this original system has a circular aperture to reduce the pupil ellipticity from the point of entry of the rod, which has the pupil ellipticity on the reticle or limited to values between approx. 0.97 and approx. 1.03 in the wafer level.
  • FIG. 12 shows the setting dependency of the intensity on the reticle for various conventional illuminations (homogeneously illuminated lighting spot), while FIG. 13 shows this setting dependency for different different ring field lighting (with open Axicon lenses) shows.
  • the curves marked with "ORIG" represent the values of the reference system (original system with circular aperture).
  • the curves marked with "MIX” show corresponding values with a pre-mixing unit (MIX).
  • the curves marked “MIX + AS” show the corresponding values for systems that have both a premixing unit and an aspherical element between the lamp and the second focal point.
  • the representations take into account that the asphere can be moved along the optical axis and accordingly for each setting can be moved to its own optimal position.
  • the pupil filling is significantly better, especially for smaller settings; accordingly, the intensity for the smallest setting increases by approx. 70%; increases for the largest setting can be achieved by approx. 7% ,
  • the setting dependency of the intensity also decreases significantly, the ratio between the minimum and maximum of the intensity being reduced via the settings from approximately 2.6 to approximately 1.7. If the premixing unit is combined with the asphere in the vicinity of the lamp, the intensities increase again significantly, especially for small settings, while no significant changes can be achieved for larger settings. The variation of the intensity over the settings thus decreases further, so that the minimum and maximum of the intensity only differ by a factor of approx. 1.5.

Abstract

L'invention concerne un dispositif d'éclairage destiné à un système d'exposition à projection pour microlithographie et fonctionnant de préférence avec une lampe à vapeur de mercure haute pression comme source lumineuse primaire. Selon un mode de réalisation de l'invention, ce dispositif d'éclairage comprend une unité d'intégration servant à mélanger la lumière de la source lumineuse primaire et comprenant au moins une barre d'intégration parallélépipédique à surface d'entrée rectangulaire (43) et à surfaces latérales (45, 47) orthogonales entres elles. Dans le chemin optique avant la surface d'entrée (43) se trouve une unité de prémélange parallélépipédique (50) à section rectangulaire, qui présente plusieurs surfaces réfléchissantes (156, 157, 158, 159) s'étendant obliquement par rapport aux surfaces latérales de la barre d'intégration. Les surfaces réfléchissantes obliques provoquent un mélange azimutal de la lumière et peuvent servir à fournir une pupille largement exempte d'ellipticité de la lumière d'éclairage derrière l'unité de prémélange.
PCT/EP2003/011000 2002-10-29 2003-10-04 Dispositif d'eclairage destine a un systeme d'exposition a projection pour microlithographie WO2004040378A2 (fr)

Priority Applications (1)

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AU2003276050A AU2003276050A1 (en) 2002-10-29 2003-10-04 Illumination device for a microlithographic projection-exposure system

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DE2002151087 DE10251087A1 (de) 2002-10-29 2002-10-29 Beleuchtungseinrichtung für eine Mikrolithographie-Projektionsbelichtungsanlage
DE10251087.3 2002-10-29

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WO2004040378A3 WO2004040378A3 (fr) 2004-12-23

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DE102011086915A1 (de) 2011-01-26 2012-07-26 Carl Zeiss Smt Gmbh Beleuchtungssystem für die Mikrolithographie

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EP1041606A1 (fr) * 1997-11-10 2000-10-04 Nikon Corporation Dispositif d'insolation
US6324330B1 (en) * 2000-07-10 2001-11-27 Ultratech Stepper, Inc. Folded light tunnel apparatus and method
US20010046038A1 (en) * 1998-04-08 2001-11-29 Johannes Catharinus H. Mulkens Lithography apparatus
US20010048562A1 (en) * 1999-12-28 2001-12-06 Bartlett Terry A. Optical architectures for combining multiple lamps in light valve projectors
EP1217450A2 (fr) * 2000-12-20 2002-06-26 Carl Zeiss Semiconductor Manufacturing Technologies Ag Intégrateur de lumière pour un dispositif d illumination

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DE4342424A1 (de) * 1993-12-13 1995-06-14 Zeiss Carl Fa Beleuchtungseinrichtung für eine Projektions-Mikrolithographie- Belichtungsanlage
JP3275575B2 (ja) * 1993-10-27 2002-04-15 キヤノン株式会社 投影露光装置及び該投影露光装置を用いたデバイスの製造方法
WO1997031298A1 (fr) * 1996-02-23 1997-08-28 Asm Lithography B.V. Unite d'eclairage destinee a un appareil optique
JP3005203B2 (ja) * 1997-03-24 2000-01-31 キヤノン株式会社 照明装置、露光装置及びデバイス製造方法
WO2000070660A1 (fr) * 1999-05-18 2000-11-23 Nikon Corporation Procede et dispositif d'exposition, et dispositif d'eclairage
JP4659223B2 (ja) * 2001-01-15 2011-03-30 キヤノン株式会社 照明装置及びこれに用いる投影露光装置並びにデバイスの製造方法

Patent Citations (5)

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Publication number Priority date Publication date Assignee Title
EP1041606A1 (fr) * 1997-11-10 2000-10-04 Nikon Corporation Dispositif d'insolation
US20010046038A1 (en) * 1998-04-08 2001-11-29 Johannes Catharinus H. Mulkens Lithography apparatus
US20010048562A1 (en) * 1999-12-28 2001-12-06 Bartlett Terry A. Optical architectures for combining multiple lamps in light valve projectors
US6324330B1 (en) * 2000-07-10 2001-11-27 Ultratech Stepper, Inc. Folded light tunnel apparatus and method
EP1217450A2 (fr) * 2000-12-20 2002-06-26 Carl Zeiss Semiconductor Manufacturing Technologies Ag Intégrateur de lumière pour un dispositif d illumination

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AU2003276050A1 (en) 2004-05-25
DE10251087A1 (de) 2004-05-19

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